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| Home Repair (alt.home.repair) For all homeowners and DIYers with many experienced tradesmen. Solve your toughest home fix-it problems. |
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#1
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GE Fused Disconnect Problems
We have a 60 amp 240 volt two pole GE fused disconnect switch in our
attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#2
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Im not a licsenced (See - I can't even spell it) electrician (personal
attackes from those who are are welcome), but it seems to you have something out of balance with how the load is distributed from the fused disconnect. (Your comments about 1 fuse burning; at least one of the legs is drawing more than it should be). Anyway - no, DO NOT replace it with a non fused disconnect, at least until you find the cause of the problem and have it corrected. Otherwise, all you are going to do is see or smell something else heating up somewhere, probably followed by your house becoming extremely warm. |
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#3
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A couple other thoughts..... I don't know if there is such a device,
but it seems to me you need to measure the current draw over a sustained period of time. Something has got to be drawing more then 60A at some point, IMHO. I may have guessed that you had a loose connection or something like that.... but replacing the disconnect and having the same symptoms reappear is .... troubling. Have you inspected the other end of the line at the heater? I'm thinking you might see some symptoms there as well, discolored/cracking insulation or something. In any event, I say you should be thankfull that the fuse is there, instead of cursing it...! |
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#4
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Jeff Wisnia wrote:
We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff I think a loose or corroded connection to the wires is getting hot, and the brass contacts conduct the heat to the fuse cap. The fuse probably has nothing to do with it other than be the weakest link. Is this aluminum wire? If so, you need to make sure the disconnect is listed for AL, and use some emory cloth on the ends of the wire, and apply de-oxide goop. Bob |
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#5
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Matt wrote:
Im not a licsenced (See - I can't even spell it) electrician (personal attackes from those who are are welcome), but it seems to you have something out of balance with how the load is distributed from the fused disconnect. (Your comments about 1 fuse burning; at least one of the legs is drawing more than it should be). I see you missed the point completely Matt. One of the legs ISN'T drawing too much current, it's just resistive heating in the switch contacts which increases over time until it gets hot enough to make the fuse fail from heat, NOT current overload. FWIW my Amprobe says that what's flowing out of one leg is flowing into the other and verse-visa. And, it hasn't always been the same leg which heats a fuse clip enough to make the fuse fail either. Anyway - no, DO NOT replace it with a non fused disconnect, at least until you find the cause of the problem and have it corrected. Otherwise, all you are going to do is see or smell something else heating up somewhere, probably followed by your house becoming extremely warm. If you can explain why Matt, I'll be all ears. For those who don't know how a GE fused disconnect is constructed; One side of the each of the supply end fuse clips is flat, not curved, and is used as stationary contacts for the spring loaded switch arm to slide into engagement with. So, any resistive heating occuring at those contacts gets conducted directly to the fuse end cap. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#6
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Why do you have to get all snooty?
I see you missed the point completely Matt. [Fine, I won't reply to any of your questions in future, as I risk missing your point. Perhaps next time you would start out your post with: This is a question for ANYONE BUT MATT]. One of the legs ISN'T drawing too much current, it's just resistive heating in the switch contacts which increases over time until it gets hot enough to make the fuse fail from heat, NOT current overload. FWIW my Amprobe says that what's flowing out of one leg is flowing into the other and verse-visa. (Should have said so before you got all snooty) And, it hasn't always been the same leg which heats a fuse clip enough to make the fuse fail either. [Good. Then they both do it. That's MUCH better.] If you can explain why Matt, I'll be all ears. [Something about how there are 5 billion fused disconnects in the world, but ONLY YOURS is overheating. Dunno though, I guess you just got the same bad model, not once, BUT TWICE.] For those who don't know how a GE fused disconnect is constructed; One side of the each of the supply end fuse clips is flat, not curved, and is used as stationary contacts for the spring loaded switch arm to slide into engagement with. So, any resistive heating occuring at those contacts gets conducted directly to the fuse end cap. [Then why the **** are you even asking for opinions? Sounds like you are a master electrician, and an expert at how disconnects are manufactered. Congratulations! You just answered ALL your own questions. Next time, save us the trouble and just stay silent. [On second thought - tear out that fused disconnect and REPLACE IT NOW with a non fused one.] |
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#7
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Also, another tip, much easier, and much less expensive.
Just replace the fuses with copper pipe. |
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#8
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Jeff Wisnia wrote:
We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff Jeff Check the label on the unit to see what Over Current Protective Device is called for by the manufacturer. When the electrician installs a fused disconnect it is often because the manufacturer specified fuses rather than allowing the branch circuit breaker to serve as the air handler / heater protection. If the label does allow a breaker for protection and you can still buy breakers that fit your panel then you can install an ACHR rated breaker and change the disconnect to an unfused one. One common reason for switch terminals to fail is that the circuit uses Aluminum wire and the terminations were over or under torqued. Terminations for aluminum conductors need to be tightened with a torque wrench or torque screw driver. As others have already pointed out the stripped end of Aluminum wire should be cleaned with a stiff wire brush or with emery cloth and then immediately coated with anti oxidation paste such as Noalox®. -- Tom H |
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#10
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zxcvbob wrote:
Jeff Wisnia wrote: We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end cap on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff I think a loose or corroded connection to the wires is getting hot, and the brass contacts conduct the heat to the fuse cap. The fuse probably has nothing to do with it other than be the weakest link. Is this aluminum wire? If so, you need to make sure the disconnect is listed for AL, and use some emory cloth on the ends of the wire, and apply de-oxide goop. Bob Thanks Bob. And no,it isn't the wire connections, they are all copper and tighter than a tick and don't show any signs of overheating. All the discoloration and oxidation is on the moving switch arms and the stationary contacts they rest against when the switch is closed. My best guess now is that the leaf springs which create the contact force may take a set with time and not press the contacts together hard enough to prevent heating. That would be analogous to your reference to the wire connections not being tight. What I was really fishing for was someone with wider experience to confirm my suspicion that those GE switched disconnects have a proclivity for failing that way after long periods of use without having been switched off and back on. Switching them occasionally might even help prevent the problem by mechanically wiping over the contact areas and scrubbing off the oxidation. I was also looking for confirmation that a 60 amp non-fused disconnect would be an applicable replacement since the circuit is already protected by a 60 amp breaker. I will let the group judge Matt and his responsess for themselves, as he's convinced me of his inability to follow and understand a technical description of something as simple as overheated switch contacts caused by contact resistance. I made plain that was what was happening in the second paragraph of my OP. Further responses to Matt from me would be useless. As for Matt's suggestion that the fuses be replaced by copper pipe shunts, that wouldn't do squat to eliminate the contact heating, it would just let that heating continue and get worse until the nonmetalic switch parts charred enough so that the switch contacts fell apart and opened the circuit. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#11
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Jeff Wisnia wrote:
zxcvbob wrote: Jeff Wisnia wrote: We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end cap on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff I think a loose or corroded connection to the wires is getting hot, and the brass contacts conduct the heat to the fuse cap. The fuse probably has nothing to do with it other than be the weakest link. Is this aluminum wire? If so, you need to make sure the disconnect is listed for AL, and use some emory cloth on the ends of the wire, and apply de-oxide goop. Bob Thanks Bob. And no,it isn't the wire connections, they are all copper and tighter than a tick and don't show any signs of overheating. All the discoloration and oxidation is on the moving switch arms and the stationary contacts they rest against when the switch is closed. My best guess now is that the leaf springs which create the contact force may take a set with time and not press the contacts together hard enough to prevent heating. That would be analogous to your reference to the wire connections not being tight. What I was really fishing for was someone with wider experience to confirm my suspicion that those GE switched disconnects have a proclivity for failing that way after long periods of use without having been switched off and back on. Switching them occasionally might even help prevent the problem by mechanically wiping over the contact areas and scrubbing off the oxidation. I was also looking for confirmation that a 60 amp non-fused disconnect would be an applicable replacement since the circuit is already protected by a 60 amp breaker. I will let the group judge Matt and his responsess for themselves, as he's convinced me of his inability to follow and understand a technical description of something as simple as overheated switch contacts caused by contact resistance. I made plain that was what was happening in the second paragraph of my OP. Further responses to Matt from me would be useless. As for Matt's suggestion that the fuses be replaced by copper pipe shunts, that wouldn't do squat to eliminate the contact heating, it would just let that heating continue and get worse until the nonmetalic switch parts charred enough so that the switch contacts fell apart and opened the circuit. Jeff If this is one of those pull out the block disconnects, it's junk. Replace it with a real fused disconnect, one that operates from a side mounted handle. When you see the price on a real disconnect you will understand why lowest bidder contractors use the pull out style. Dave |
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#12
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Jeff if there is no heat as a result of a loose connection or bad contact, I
am wondering if the attic ambient temperature is a factor. Check the disconnect's label to see if there is a mention of allowable ambient temperature. Another thing would be to check the label to see if the disconnect is rated for the type of load that you have. Also check the nameplate on the heating unit to see what it requires for a disconnect. It should say fuse or HACR breaker and give an amp rating. One other thing would be to check the connections inside of the heating unit to make sure that they are all tight. Have you checked starting current? Your 40 amp draw sounds like running current. The unit probably has a much higher starting load. Also, check the voltage when starting and running at the disconnect. If the voltage is too low the current draw can go up. That's all I can think of. John Grabowski http://www.mrelectrician.tv "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#13
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Just read thru all the posts so far and -think- I understand your =
situation. It's pretty hard to tell, but one thing no one mentioned is = the "area" of the switch contacts. The smaller the contact area, the = faster it can heat up, so if there's any hot weather relationship, it's = possible the "set" you mentioned in one post was enough to actually = "offset" it a tad, and thus drop the sq. in/sq. cm area of the = connection. 40A running current is enough to cause some heat buildup = during normal operation; so, on a hot day with a start-surge, in a = super-heated attic, the buildup could take a run-away attitude. The = hotter the metal gets, the more impedance it presents via its own = properties, plus that faster oxidation can form, and off it goes. The = heating process is often a logarithmic as opposed to linear pattern, so = what takes ten seconds at first, may only take 0.1 seconds in a minute, = and so on, meaning the heat increases exponentially also. Is there a = heat-rise spec on the plate? =20 Something tells me that 40A ac might be at or beyond the "running" = (constant current) limit of the contacts and that the 60A spec is a = timed spec: eg, 60 A for x minutes or hours vs. constant current. No, = I'm not talking slo-blo type of stuff. If so, then 40A would be too = much for it. This would be worth taking up with the manufacturer or = better yet, their eng dept if you can find an "in" to them. Some = places, Square D for instance, make it easy to talk to an engineer, = others won't let you in a million years, but it's worth asking for = someone with design experience, or the actual technical design specs of = the switch. =20 Since this has happened so often, relatively speaking, it just about has = to be a design vs. use issue. Perhaps if you posted the specs from the = switch plate, someone could make a better estimate. =20 Any chance you can parallel a fan to cool the contacts when they = close, and see if that extends the time it takes, or even stops the = burning? Probably not; sounds like an awful long time between problems. = Nah, guess it wouldn't work; too close to the fuses themselves to = separate the air flow. =20 Anyway, them's my inejukatid thoughts. A little far out, but still = within the realm of possibility. =20 Pop Jeff Wisnia wrote: We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. =20 That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. =20 I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. =20 About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. =20 The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. =20 Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? =20 Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? =20 Comments? =20 Jeff --=20 --=20 One should not be so p-h-i-l-o-p-o-L-e-m-i-c lest they be seen as disputatious. |
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#14
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John Grabowski wrote:
Jeff if there is no heat as a result of a loose connection or bad contact, I am wondering if the attic ambient temperature is a factor. Check the disconnect's label to see if there is a mention of allowable ambient temperature. I've been up in the attic in the heat of summer and it really isn't unbearable. Since the fused disconnect in question is rated for outside service, I'd expect its inside would get hotter that the attic if it was used outside exposed to direct sunlight, so I doubt that's a factor. Another thing would be to check the label to see if the disconnect is rated for the type of load that you have. Also check the nameplate on the heating unit to see what it requires for a disconnect. It should say fuse or HACR breaker and give an amp rating. One other thing would be to check the connections inside of the heating unit to make sure that they are all tight. Have you checked starting current? Your 40 amp draw sounds like running current. The unit probably has a much higher starting load. Also, check the voltage when starting and running at the disconnect. If the voltage is too low the current draw can go up. I didn't check the voltage, but as the bulk of the load is just resistance heaters, the current would have to be lower, not higher, if the voltage was low, wouldn't it? The nameplate on the air handler says 35.5 amps for the auxillary heaters and 2.5 amps for the blower motor. that should be trivial for a 60 amp disconnect. And, if there was a huge starting surge I'd expect the 60 amp standard fuses (they're not "lag" types) would blow. They don't. The fuse links in the two charred fuses I replaced today were intact, they just became unsoldered from the end caps which got heated by normal running current levels passing through the poor switch contacts. If the disconnect is rated for 60 amps and the 60 amp fuses don't blow, but the switch contacts fry, there pretty much has to be something wrong with those switch contacts, eh? That's all I can think of. I checked with a electrical contractors and an HVAC guy in my Rotary Club this evening and they both said they've seen the same sort of failures in GE fused disconnects, so I guess I have my answer, and it's what I surmised. I'm convinced here's nothing inherently wrong with anything else, things work just as they should for the better part of a year and then the switch contacts start to oxidize and the problems start. When I clean up the contacts things go back to being good until about a year later. I think I've about "saucered and blowed" this one now. G Jeff John Grabowski http://www.mrelectrician.tv "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#15
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Pop wrote:
Just read thru all the posts so far and -think- I understand your situation. It's pretty hard to tell, but one thing no one mentioned is the "area" of the switch contacts. The smaller the contact area, the faster it can heat up, so if there's any hot weather relationship, it's possible the "set" you mentioned in one post was enough to actually "offset" it a tad, and thus drop the sq. in/sq. cm area of the connection. 40A running current is enough to cause some heat buildup during normal operation; so, on a hot day with a start-surge, in a super-heated attic, the buildup could take a run-away attitude. The hotter the metal gets, the more impedance it presents via its own properties, plus that faster oxidation can form, and off it goes. The heating process is often a logarithmic as opposed to linear pattern, so what takes ten seconds at first, may only take 0.1 seconds in a minute, and so on, meaning the heat increases exponentially also. Is there a heat-rise spec on the plate? Something tells me that 40A ac might be at or beyond the "running" (constant current) limit of the contacts and that the 60A spec is a timed spec: eg, 60 A for x minutes or hours vs. constant current. No, I'm not talking slo-blo type of stuff. If so, then 40A would be too much for it. This would be worth taking up with the manufacturer or better yet, their eng dept if you can find an "in" to them. Some places, Square D for instance, make it easy to talk to an engineer, others won't let you in a million years, but it's worth asking for someone with design experience, or the actual technical design specs of the switch. Since this has happened so often, relatively speaking, it just about has to be a design vs. use issue. Perhaps if you posted the specs from the switch plate, someone could make a better estimate. Any chance you can parallel a fan to cool the contacts when they close, and see if that extends the time it takes, or even stops the burning? Probably not; sounds like an awful long time between problems. Nah, guess it wouldn't work; too close to the fuses themselves to separate the air flow. Anyway, them's my inejukatid thoughts. A little far out, but still within the realm of possibility. Pop All good stuff thanks! The only offsetting thing I can say is that the auxillary heaters typically only get switched on when it gets too cold outside for the heat pump to take care of the heating requirements, and that's the time of year when the attic is cold, not hot. The rest of the year the only load is just the fan motor, a ****ant 2.5 amps. So, I doubt that high ambient temperature is the troublemaker. Rather than turn this "one off" situation into a major research project, I think I'll go with replacing the GE fused disconnect with an unfused disconnect and see what happens in a year. G Thanks again. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#16
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I'm just curious
... if you know. what make and part number fuse have you been using "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#17
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bumtracks wrote:
I'm just curious .. if you know. what make and part number fuse have you been using OK, I got your question in time to pull the remains of the fuses out of the workshop trash can. The fuse which opened this time, because the solder holding the fuse link to the end cap next to the switch contacts melted, has GE's name on it and is marked 60 AMP, One-Time Fuse, 250 VAC or less, 10,000 Amps Internal Rating, Class H. The other fuse in the disconnect, which fell apart when I pulled it out because the fibre had toasted but the fuse link was still intact and soldered to both caps, Was marked "Ace Hardware", Type NON, One-Time Fuse, 250 Volts or less, 50,000 Amps internal rating, Class K5. Gee, maybe now that Matt guy will come back in to tell me the problems I've had with this disconnect were likely caused either by using an Ace Hardware fuse in a GE fused disconnect or the fact that the pair of fuses was "unbalanced" by 40,000 Amps. G I am always suprised to see just how skinny fuse links actually are in relation to the gage of the wires in the circuit they are protecting. I just miked the link from one of those charred fuses and its only .008" thick by .065" wide at the narrow spots. Obviously it has to be that size to perform its function, but that small a cross section sure doesn't "look" like it'd carry 60 amps continuously. Sorry to waste so much bandwidth on this thread guys, it's my curious mind always wanting to find the "real reason" why things happen. Jeff "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#18
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in commercial disconnects of time gone past,
it wasn't odd to see 'fuse clip clamps' adding pressure to the clip the fuse snaps into as they would get weak with age and heat up, usually just melting the link. clip clamps look like little springy packman jaws with a knob that tightens them adding additional spring pressure. imagine there's still some out there doing their job. "Jeff Wisnia" wrote in message ... bumtracks wrote: I'm just curious .. if you know. what make and part number fuse have you been using OK, I got your question in time to pull the remains of the fuses out of the workshop trash can. The fuse which opened this time, because the solder holding the fuse link to the end cap next to the switch contacts melted, has GE's name on it and is marked 60 AMP, One-Time Fuse, 250 VAC or less, 10,000 Amps Internal Rating, Class H. The other fuse in the disconnect, which fell apart when I pulled it out because the fibre had toasted but the fuse link was still intact and soldered to both caps, Was marked "Ace Hardware", Type NON, One-Time Fuse, 250 Volts or less, 50,000 Amps internal rating, Class K5. Gee, maybe now that Matt guy will come back in to tell me the problems I've had with this disconnect were likely caused either by using an Ace Hardware fuse in a GE fused disconnect or the fact that the pair of fuses was "unbalanced" by 40,000 Amps. G I am always suprised to see just how skinny fuse links actually are in relation to the gage of the wires in the circuit they are protecting. I just miked the link from one of those charred fuses and its only .008" thick by .065" wide at the narrow spots. Obviously it has to be that size to perform its function, but that small a cross section sure doesn't "look" like it'd carry 60 amps continuously. Sorry to waste so much bandwidth on this thread guys, it's my curious mind always wanting to find the "real reason" why things happen. Jeff "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#19
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bumtracks wrote:
in commercial disconnects of time gone past, it wasn't odd to see 'fuse clip clamps' adding pressure to the clip the fuse snaps into as they would get weak with age and heat up, usually just melting the link. clip clamps look like little springy packman jaws with a knob that tightens them adding additional spring pressure. imagine there's still some out there doing their job. Yep, I remember those. But, I'm darn cerain I've got this one diagnosed corectly, as the other ends of the moving switch arms, the ones which mate with the contacts at the input terminals, also oxidize and show heat discoloration. And before somebody asks me again, the input wire terminal screws ARE tight, the wires in them are copper, not aluminum, and there's no signs of heating up there. Also, the output ends of the fuses have never had any problems like that, the clips on those ends are still in their original (tin plated?) condition, with no signs of overheating there. I also remember cartridge fuses with replaceable links, even in smaller sizes like 20 amps. I don't know if they are still made now that we've become used to living in a "throw away" economy. Being a depression era baby, I really miss frugal stuff like that. Jeff "Jeff Wisnia" wrote in message ... bumtracks wrote: I'm just curious .. if you know. what make and part number fuse have you been using OK, I got your question in time to pull the remains of the fuses out of the workshop trash can. The fuse which opened this time, because the solder holding the fuse link to the end cap next to the switch contacts melted, has GE's name on it and is marked 60 AMP, One-Time Fuse, 250 VAC or less, 10,000 Amps Internal Rating, Class H. The other fuse in the disconnect, which fell apart when I pulled it out because the fibre had toasted but the fuse link was still intact and soldered to both caps, Was marked "Ace Hardware", Type NON, One-Time Fuse, 250 Volts or less, 50,000 Amps internal rating, Class K5. Gee, maybe now that Matt guy will come back in to tell me the problems I've had with this disconnect were likely caused either by using an Ace Hardware fuse in a GE fused disconnect or the fact that the pair of fuses was "unbalanced" by 40,000 Amps. G I am always suprised to see just how skinny fuse links actually are in relation to the gage of the wires in the circuit they are protecting. I just miked the link from one of those charred fuses and its only .008" thick by .065" wide at the narrow spots. Obviously it has to be that size to perform its function, but that small a cross section sure doesn't "look" like it'd carry 60 amps continuously. Sorry to waste so much bandwidth on this thread guys, it's my curious mind always wanting to find the "real reason" why things happen. Jeff "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#20
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"Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle Jeff , These fuse disconnects are stated as rated at 60 amps but if you read the amp draw rating in the data plate with it. You will see it is suppose to be used on amp draws of less than 40 amps. It states that it will handle short time useage of near 60 amps but when put in a contenous amp draw the 40 amps your drawing on it become the max it will handle. I have the Connecuit Electric type I use on condenser outside and they are rated at 60 amps but if you read closely you will see it says contenous use 40 amps is the MAX. it will handle. You just don't run anything at Max. By running this disconnect at 40 amps is like it says on the Lexus LS-400 Maxium operating speed is 161 M.P.H. and then you can run it at that speed and be safe. So if you don't run your car at Max. Speed 160 M.P.H , Don't run your 60 Amp disconnect Rated at Max. Amps 40 Amps. I have a rule I use and that is I will rate the load at 1/2 the rated load on the disconnect like it rated at 60 amps on the cover. I will not put more that 30 amps on it contenously. And yes my Lexus LS-400 will go over 161 M.P.H. at 165 M.P.H. and is the model before the Kill switches put on them. And yes I drive the speed limit most of the time and also drive my disconnects below the amp limit. TURTLE |
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#21
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"Jeff Wisnia" wrote in message ... bumtracks wrote: in commercial disconnects of time gone past, it wasn't odd to see 'fuse clip clamps' adding pressure to the clip the fuse snaps into as they would get weak with age and heat up, usually just melting the link. clip clamps look like little springy packman jaws with a knob that tightens them adding additional spring pressure. imagine there's still some out there doing their job. Yep, I remember those. But, I'm darn cerain I've got this one diagnosed corectly, as the other ends of the moving switch arms, the ones which mate with the contacts at the input terminals, also oxidize and show heat discoloration. And before somebody asks me again, the input wire terminal screws ARE tight, the wires in them are copper, not aluminum, and there's no signs of heating up there. Also, the output ends of the fuses have never had any problems like that, the clips on those ends are still in their original (tin plated?) condition, with no signs of overheating there. I also remember cartridge fuses with replaceable links, even in smaller sizes like 20 amps. I don't know if they are still made now that we've become used to living in a "throw away" economy. Being a depression era baby, I really miss frugal stuff like that. Jeff This is Turtle. Yes the fuse link type fuses are still made but nobody buys them anymore. The links cost $.80 and the replacement fuse cost $1.09. It's not really worth it. Yes we are in the Throw away Economy Generation ! TURTLE |
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#22
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"Matt" wrote in message ups.com... Also, another tip, much easier, and much less expensive. Just replace the fuses with copper pipe. This is Turtle. Matt you don't need to get your draws in a knot for you stated you was not a electrician and your answer would be taken as a consumer answers for your reply would be a view of a consumer and not the so called professional. Get Off the Soap box and just be one of the people here. TURTLE |
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#23
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"HaHaHa" wrote in message ... From: Jeff Wisnia We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia Jeff, any particular reason the disco is fused? Usually, fused disconnects are redundant. Having a disco within sight of the equipment is required, but to include overcurrent protection twice (once at the main panel, and again at the disco) seems silly. Or replace with a simple, 2-pole circuit-breaker disconnect. This is Turtle. Ha , The Fused disconnect cost about $15.00 and breaker & can will cost about $40.00+ and you ask him why he uses the fused disconnect box. Now if everybody here was Million aires your reply would ok. TURTLE |
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Perhaps you are right Turtle.... but nothing ****es me off more than to
take the time to try to help someone, at their request, and then have them come back and insult me for it. Even if I'm completely off base with my answer, it just irks me to have the OP slam me for trying to help. We all know the others here will do a nice job of gutting anyone who gives a completely wrong answer.... and I can accept that, ask for forgiveness, and move on.... but not from the OP. In this case, the guy had a disconnect that's overheating. His solution? Replace a fused disconenct with a non fused one. This does nothing to address the core problem (which I believe you and others have very well pinpointed - his disco is undersized). No, his brilliant solution was that GE makes crappy disconnects, he heard it from someone who knows somebody who knows an electrician, after all. Maybe I was off base by getting my panties in a twist. If so, I apologize to the OP and others. And as you mentioned what I admitted, I'm not an electrician. But it doesn't take an expert to know that when an electrical circuit is overheating to the point where cartridge fuses are melting, something is wrong somewhere, and the very last possibility to consider is that someone mfrs a crappy product. This guy even went to the trouble of replacing his "crappy" product with the same "crap", and surprise! Got the same results. Yeah, it's gotta be a bad disconnect. I'll replace it with a non fused one... that will fix it! Had he gone ahead and done that, what do you think the outcome would have been, assuming he replaced it with the same specs as the disco. Fire? I think it's likely, especially in an attic. Which is all I was trying to point out in the first place. And now I'll jump off my soapbox..... |
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#25
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HaHaHa wrote:
From: Jeff Wisnia We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia Jeff, any particular reason the disco is fused? You'd have to ask the original installer. I was too busy making sure lots of other stuff got done OK while the place was being built and didn't stop to question why it was fused then. I'd already agreed to the overall price of the HVAC system, so questioning why it needed fuses wouldn't have made any price difference anyway. G Fuses there never made much engineering sense to me though. But, a couple of others on this thread have raised questions about whether the equipment manufacturer may have particular requirements about the line feeding it being protected by fuses rather than just a breaker. I can't think of any technical reason for that requirement for a piece of equipment which is principally just a 1/4 hp fan motor with occassionally a 35.5 amp resistive heater load added to it. Usually, fused disconnects are redundant. Having a disco within sight of the equipment is required, but to include overcurrent protection twice (once at the main panel, and again at the disco) seems silly. Or replace with a simple, 2-pole circuit-breaker disconnect. I kinda thought that "simple is better" that's why yesterday I bought what looks like a simple and robust 60 amp Square-D "plug disconnect" which I'll probably swap in this weekend. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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TURTLE wrote:
"Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle Jeff , These fuse disconnects are stated as rated at 60 amps but if you read the amp draw rating in the data plate with it. You will see it is suppose to be used on amp draws of less than 40 amps. It states that it will handle short time useage of near 60 amps but when put in a contenous amp draw the 40 amps your drawing on it become the max it will handle. I have the Connecuit Electric type I use on condenser outside and they are rated at 60 amps but if you read closely you will see it says contenous use 40 amps is the MAX. it will handle. You just don't run anything at Max. By running this disconnect at 40 amps is like it says on the Lexus LS-400 Maxium operating speed is 161 M.P.H. and then you can run it at that speed and be safe. So if you don't run your car at Max. Speed 160 M.P.H , Don't run your 60 Amp disconnect Rated at Max. Amps 40 Amps. Well now, I'll check the specs and if that's the case it sure makes sense now! And too bad the original installer didn't see it that way too, it would have saved me a lot of nuisance fixups. Thanks, and I hope the 60 amp Aquare-D non-fused plug type disconnect switch I just bough yesterday isnn's similarly rated. G Jeff I have a rule I use and that is I will rate the load at 1/2 the rated load on the disconnect like it rated at 60 amps on the cover. I will not put more that 30 amps on it contenously. And yes my Lexus LS-400 will go over 161 M.P.H. at 165 M.P.H. and is the model before the Kill switches put on them. And yes I drive the speed limit most of the time and also drive my disconnects below the amp limit. TURTLE |
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"Matt" wrote in message ups.com... Perhaps you are right Turtle.... but nothing ****es me off more than to take the time to try to help someone, at their request, and then have them come back and insult me for it. Even if I'm completely off base with my answer, it just irks me to have the OP slam me for trying to help. We all know the others here will do a nice job of gutting anyone who gives a completely wrong answer.... and I can accept that, ask for forgiveness, and move on.... but not from the OP. In this case, the guy had a disconnect that's overheating. His solution? Replace a fused disconenct with a non fused one. This does nothing to address the core problem (which I believe you and others have very well pinpointed - his disco is undersized). No, his brilliant solution was that GE makes crappy disconnects, he heard it from someone who knows somebody who knows an electrician, after all. Maybe I was off base by getting my panties in a twist. If so, I apologize to the OP and others. And as you mentioned what I admitted, I'm not an electrician. But it doesn't take an expert to know that when an electrical circuit is overheating to the point where cartridge fuses are melting, something is wrong somewhere, and the very last possibility to consider is that someone mfrs a crappy product. This guy even went to the trouble of replacing his "crappy" product with the same "crap", and surprise! Got the same results. Yeah, it's gotta be a bad disconnect. I'll replace it with a non fused one... that will fix it! Had he gone ahead and done that, what do you think the outcome would have been, assuming he replaced it with the same specs as the disco. Fire? I think it's likely, especially in an attic. Which is all I was trying to point out in the first place. And now I'll jump off my soapbox..... This is Turtle Get a Grip This is UserNet ! TURTLE |
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Perhaps so, Turtle.....
But you are the LAST PERSON ON EARTH to be giving "get a grip" advice. Or perhaps you think your recent posts in alt.hvac resemble those of a sane man? I know, lets go ask Paul and Bill. Or maybe Bubba would care to chime in at this time. |
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TURTLE wrote:
"Matt" wrote in message ups.com... Perhaps you are right Turtle.... but nothing ****es me off more than to take the time to try to help someone, at their request, and then have them come back and insult me for it. Even if I'm completely off base with my answer, it just irks me to have the OP slam me for trying to help. We all know the others here will do a nice job of gutting anyone who gives a completely wrong answer.... and I can accept that, ask for forgiveness, and move on.... but not from the OP. In this case, the guy had a disconnect that's overheating. His solution? Replace a fused disconenct with a non fused one. This does nothing to address the core problem (which I believe you and others have very well pinpointed - his disco is undersized). No, his brilliant solution was that GE makes crappy disconnects, he heard it from someone who knows somebody who knows an electrician, after all. Maybe I was off base by getting my panties in a twist. If so, I apologize to the OP and others. And as you mentioned what I admitted, I'm not an electrician. But it doesn't take an expert to know that when an electrical circuit is overheating to the point where cartridge fuses are melting, something is wrong somewhere, and the very last possibility to consider is that someone mfrs a crappy product. This guy even went to the trouble of replacing his "crappy" product with the same "crap", and surprise! Got the same results. Yeah, it's gotta be a bad disconnect. I'll replace it with a non fused one... that will fix it! Had he gone ahead and done that, what do you think the outcome would have been, assuming he replaced it with the same specs as the disco. Fire? I think it's likely, especially in an attic. Which is all I was trying to point out in the first place. And now I'll jump off my soapbox..... This is Turtle Get a Grip This is UserNet ! TURTLE We know that, but you'll never convice Matt. He seems so touchy I think maybe he sleeps on sandpaper sheets or a bed of nails every night. I should be the one ****ing and moaning about the distortions he makes about my posts and the sarcastic things he says about me, all because I told him he missed the central point in my OP and then I asked him to explain why he thought replacing the fused disconnect with a non-fused one was going to set fire to my house. Oh well, I guess I'll just have to accept Matt's garbage graciously, the phrase noblesse oblige comes to mind... I'm gonna check the paper label inside that GE fused disconnect when I get home tonight, I'm curious to know if I missed seeing something on it about the maximum continuous current rating being lower than 60 amps. If so you've sure tought me something - along the lines of "The big print giveth and the fine print taketh away." G Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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"Jeff Wisnia" wrote in message ... TURTLE wrote: "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle Jeff , These fuse disconnects are stated as rated at 60 amps but if you read the amp draw rating in the data plate with it. You will see it is suppose to be used on amp draws of less than 40 amps. It states that it will handle short time useage of near 60 amps but when put in a contenous amp draw the 40 amps your drawing on it become the max it will handle. I have the Connecuit Electric type I use on condenser outside and they are rated at 60 amps but if you read closely you will see it says contenous use 40 amps is the MAX. it will handle. You just don't run anything at Max. By running this disconnect at 40 amps is like it says on the Lexus LS-400 Maxium operating speed is 161 M.P.H. and then you can run it at that speed and be safe. So if you don't run your car at Max. Speed 160 M.P.H , Don't run your 60 Amp disconnect Rated at Max. Amps 40 Amps. Well now, I'll check the specs and if that's the case it sure makes sense now! And too bad the original installer didn't see it that way too, it would have saved me a lot of nuisance fixups. Thanks, and I hope the 60 amp Aquare-D non-fused plug type disconnect switch I just bough yesterday isnn's similarly rated. G Jeff This is Turtle. No that Square - D breaker looking disconnect is rated above the 40 amps but usely in about 2 to 4 years the breaker will burn inside the breaker and go out and then you can replace it with a real breaker square- D and keep going. A lot of HVAC people don't like them for that call back coming in 2 to 4 years. Now if you replace it now with a real breaker to apply to the application you will not see it down the road. TURTLE |
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TURTLE wrote:
"Jeff Wisnia" wrote in message ... TURTLE wrote: "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle Jeff , These fuse disconnects are stated as rated at 60 amps but if you read the amp draw rating in the data plate with it. You will see it is suppose to be used on amp draws of less than 40 amps. It states that it will handle short time useage of near 60 amps but when put in a contenous amp draw the 40 amps your drawing on it become the max it will handle. I have the Connecuit Electric type I use on condenser outside and they are rated at 60 amps but if you read closely you will see it says contenous use 40 amps is the MAX. it will handle. You just don't run anything at Max. By running this disconnect at 40 amps is like it says on the Lexus LS-400 Maxium operating speed is 161 M.P.H. and then you can run it at that speed and be safe. So if you don't run your car at Max. Speed 160 M.P.H , Don't run your 60 Amp disconnect Rated at Max. Amps 40 Amps. Well now, I'll check the specs and if that's the case it sure makes sense now! And too bad the original installer didn't see it that way too, it would have saved me a lot of nuisance fixups. Thanks, and I hope the 60 amp Aquare-D non-fused plug type disconnect switch I just bough yesterday isnn's similarly rated. G Jeff This is Turtle. No that Square - D breaker looking disconnect is rated above the 40 amps but usely in about 2 to 4 years the breaker will burn inside the breaker and go out and then you can replace it with a real breaker square- D and keep going. A lot of HVAC people don't like them for that call back coming in 2 to 4 years. Now if you replace it now with a real breaker to apply to the application you will not see it down the road. TURTLE Do they make a 100A disconnect that just has a pull-out block with 2 cartridge fuses in it? That's what I think I would use if they are available that big. Put in whatever size fuses you actually need to protect the heater, (45A?) or just put 100A fuses in it and let the breaker back in the main panel provide the protection. Bob |
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#32
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"Jeff Wisnia" wrote in message ... TURTLE wrote: "Matt" wrote in message ups.com... Perhaps you are right Turtle.... but nothing ****es me off more than to take the time to try to help someone, at their request, and then have them come back and insult me for it. Even if I'm completely off base with my answer, it just irks me to have the OP slam me for trying to help. We all know the others here will do a nice job of gutting anyone who gives a completely wrong answer.... and I can accept that, ask for forgiveness, and move on.... but not from the OP. In this case, the guy had a disconnect that's overheating. His solution? Replace a fused disconenct with a non fused one. This does nothing to address the core problem (which I believe you and others have very well pinpointed - his disco is undersized). No, his brilliant solution was that GE makes crappy disconnects, he heard it from someone who knows somebody who knows an electrician, after all. Maybe I was off base by getting my panties in a twist. If so, I apologize to the OP and others. And as you mentioned what I admitted, I'm not an electrician. But it doesn't take an expert to know that when an electrical circuit is overheating to the point where cartridge fuses are melting, something is wrong somewhere, and the very last possibility to consider is that someone mfrs a crappy product. This guy even went to the trouble of replacing his "crappy" product with the same "crap", and surprise! Got the same results. Yeah, it's gotta be a bad disconnect. I'll replace it with a non fused one... that will fix it! Had he gone ahead and done that, what do you think the outcome would have been, assuming he replaced it with the same specs as the disco. Fire? I think it's likely, especially in an attic. Which is all I was trying to point out in the first place. And now I'll jump off my soapbox..... This is Turtle Get a Grip This is UserNet ! TURTLE We know that, but you'll never convice Matt. He seems so touchy I think maybe he sleeps on sandpaper sheets or a bed of nails every night. I should be the one ****ing and moaning about the distortions he makes about my posts and the sarcastic things he says about me, all because I told him he missed the central point in my OP and then I asked him to explain why he thought replacing the fused disconnect with a non-fused one was going to set fire to my house. Oh well, I guess I'll just have to accept Matt's garbage graciously, the phrase noblesse oblige comes to mind... I'm gonna check the paper label inside that GE fused disconnect when I get home tonight, I'm curious to know if I missed seeing something on it about the maximum continuous current rating being lower than 60 amps. If so you've sure tought me something - along the lines of "The big print giveth and the fine print taketh away." G Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle. Sometimes it is written on the plastic cover in the front and in the plastic where you can't see it very well. Most of the rating they give these disconnects is they run the disconnect at different amp rating for a day and find out just how much it will take to burn it up. Then what ever the disconnect will run at for a day. That is the amp rating it is set at. Most of the time if the rating is for 60 amps and you run 61 amps on it for a day. It will fry and burn so the set it just below that burn level at 60 amps. Alway stick to the Disconnect rules of only run 1/2 the amps of a disconnect rating and call it Max. Hey i was tring to support old Matt and give him some support in his feeling of being disrespected in his post by what he as saying and low and behold he chops on me for be a Asshole disrespecting others and me tring to give him some support and respect. i guess the only respect old Matt will find is by looking respect up in the dictionary and get it there by reading about it. TURTLE |
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#33
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"zxcvbob" wrote in message ... TURTLE wrote: "Jeff Wisnia" wrote in message ... TURTLE wrote: "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle Jeff , These fuse disconnects are stated as rated at 60 amps but if you read the amp draw rating in the data plate with it. You will see it is suppose to be used on amp draws of less than 40 amps. It states that it will handle short time useage of near 60 amps but when put in a contenous amp draw the 40 amps your drawing on it become the max it will handle. I have the Connecuit Electric type I use on condenser outside and they are rated at 60 amps but if you read closely you will see it says contenous use 40 amps is the MAX. it will handle. You just don't run anything at Max. By running this disconnect at 40 amps is like it says on the Lexus LS-400 Maxium operating speed is 161 M.P.H. and then you can run it at that speed and be safe. So if you don't run your car at Max. Speed 160 M.P.H , Don't run your 60 Amp disconnect Rated at Max. Amps 40 Amps. Well now, I'll check the specs and if that's the case it sure makes sense now! And too bad the original installer didn't see it that way too, it would have saved me a lot of nuisance fixups. Thanks, and I hope the 60 amp Aquare-D non-fused plug type disconnect switch I just bough yesterday isnn's similarly rated. G Jeff This is Turtle. No that Square - D breaker looking disconnect is rated above the 40 amps but usely in about 2 to 4 years the breaker will burn inside the breaker and go out and then you can replace it with a real breaker square- D and keep going. A lot of HVAC people don't like them for that call back coming in 2 to 4 years. Now if you replace it now with a real breaker to apply to the application you will not see it down the road. TURTLE Do they make a 100A disconnect that just has a pull-out block with 2 cartridge fuses in it? That's what I think I would use if they are available that big. Put in whatever size fuses you actually need to protect the heater, (45A?) or just put 100A fuses in it and let the breaker back in the main panel provide the protection. Bob This is Turtle. Yes they do but your looking at about $68.00 + Tax . It will come with a lever on the out side and spaded type fuses and the fuses are about $8.00 each even being 60 amps to 100 amps sizes. The 60 amp disconnect is the breaking point between commercial and residentiual equipment and the price reflects it. Now this type fuse box / fused type disconnect will run at 90 amps till the cows come home but the 60 amp cheap o will run till the sun goes down. . The standard 60 amp fuse / disconnect $15.00 verses the 100 amp fuse box / fused disconnect at $78.44 is a far cry between them in quality and in price. At about 5 times the cost the public will not go for 5 times the price when Home Depot sells them for $15.00 and the home owner can replace them pretty easy. TURTLE |
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#34
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TURTLE wrote:
"Jeff Wisnia" wrote in message ... TURTLE wrote: "Matt" wrote in message groups.com... Perhaps you are right Turtle.... but nothing ****es me off more than to take the time to try to help someone, at their request, and then have them come back and insult me for it. Even if I'm completely off base with my answer, it just irks me to have the OP slam me for trying to help. We all know the others here will do a nice job of gutting anyone who gives a completely wrong answer.... and I can accept that, ask for forgiveness, and move on.... but not from the OP. In this case, the guy had a disconnect that's overheating. His solution? Replace a fused disconenct with a non fused one. This does nothing to address the core problem (which I believe you and others have very well pinpointed - his disco is undersized). No, his brilliant solution was that GE makes crappy disconnects, he heard it from someone who knows somebody who knows an electrician, after all. Maybe I was off base by getting my panties in a twist. If so, I apologize to the OP and others. And as you mentioned what I admitted, I'm not an electrician. But it doesn't take an expert to know that when an electrical circuit is overheating to the point where cartridge fuses are melting, something is wrong somewhere, and the very last possibility to consider is that someone mfrs a crappy product. This guy even went to the trouble of replacing his "crappy" product with the same "crap", and surprise! Got the same results. Yeah, it's gotta be a bad disconnect. I'll replace it with a non fused one... that will fix it! Had he gone ahead and done that, what do you think the outcome would have been, assuming he replaced it with the same specs as the disco. Fire? I think it's likely, especially in an attic. Which is all I was trying to point out in the first place. And now I'll jump off my soapbox..... This is Turtle Get a Grip This is UserNet ! TURTLE We know that, but you'll never convice Matt. He seems so touchy I think maybe he sleeps on sandpaper sheets or a bed of nails every night. I should be the one ****ing and moaning about the distortions he makes about my posts and the sarcastic things he says about me, all because I told him he missed the central point in my OP and then I asked him to explain why he thought replacing the fused disconnect with a non-fused one was going to set fire to my house. Oh well, I guess I'll just have to accept Matt's garbage graciously, the phrase noblesse oblige comes to mind... I'm gonna check the paper label inside that GE fused disconnect when I get home tonight, I'm curious to know if I missed seeing something on it about the maximum continuous current rating being lower than 60 amps. If so you've sure tought me something - along the lines of "The big print giveth and the fine print taketh away." G Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle. Sometimes it is written on the plastic cover in the front and in the plastic where you can't see it very well. Most of the rating they give these disconnects is they run the disconnect at different amp rating for a day and find out just how much it will take to burn it up. Then what ever the disconnect will run at for a day. That is the amp rating it is set at. Most of the time if the rating is for 60 amps and you run 61 amps on it for a day. It will fry and burn so the set it just below that burn level at 60 amps. Alway stick to the Disconnect rules of only run 1/2 the amps of a disconnect rating and call it Max. Hey i was tring to support old Matt and give him some support in his feeling of being disrespected in his post by what he as saying and low and behold he chops on me for be a Asshole disrespecting others and me tring to give him some support and respect. i guess the only respect old Matt will find is by looking respect up in the dictionary and get it there by reading about it. TURTLE Well TURTLE, once again you are the voice of experience I was looking for with my OP. I climed up and looked at the paper label inside the GE fused disconnect last nnite (Cat #TG3222-MOD6 to be specific). Off at the bottom of the label in type so small I had to work hard to pick it out, it reads, "Contact current not to exceed 80% of fuse rating for other than motor circuits." Now that's still 48 amps, and the draw I measure with the auxillary heaters on is a bit below 40 amps, but I won't quibble with the results I've got (on a sample of two), namely that the switch contacts oxidize and heat up enough to melt the solder in the fuse end caps 1-2 years after I clean them up all pretty again. And those auxillary heaters aren't working 100 percent of the time the heat's on, except in really cold weather. There were also words on the disconnect's label cautioning against the use of replaceable link fuses in that unit. It was a caution, not a rating, but there's probably good reason for them to say that. My 45 years of designing everything from fuel oil truck delivery nozzles to atomic clocks tought me that a month or so of lab testing does not equal years of running in the field. I used to have a sign on my office wall which read, "One good field test is worth a thousand expert opinions.", and another one which read, "Ther's no right way to do the wrong thing." Thanks again, Jeff -- Jeffry Wisnia http://home.comcast.net/~jwisnia18/jeff/ (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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Jeff Wisnia wrote:
.... I clim(b)ed up and looked at the paper label inside the GE fused disconnect last nnite (Cat #TG3222-MOD6 to be specific). Off at the bottom of the label in type so small I had to work hard to pick it out, it reads, "Contact current not to exceed 80% of fuse rating for other than motor circuits." ... Note that NEC requires no more than 80% of rated amperage for virtually all boxes, irrespective of manufacturer. It's a good rule of thumb that many don't adhere to. Another thing during this thread (that hadn't popped to the fore in my mind until last night for some reason) is that in the attic you may not have adequate (or any to speak of) air flow around the box so that the ambient temperature ratings may not be valid since they're based on "normal" air circulation. If the box is in an area where there isn't a convection path over/around it, it may well have an internal temperature rise well above that you observed w/ the brief open box test you did. I think the upgrade to a 100 A box would solve the issue plus, perhaps, if there is a restriction around where it is presently mounted, moving it to a more open area couldn't hurt (and just might solve the problem w/o the other box). |
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Jeez turtle,
Get a grip! This is USERNET, remember? |
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#37
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Hey,
Say hello to the folks from the fire dept for me, would ya? Thanks man! |
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TURTLE wrote:
"zxcvbob" wrote in message ... TURTLE wrote: "Jeff Wisnia" wrote in message ... TURTLE wrote: "Jeff Wisnia" wrote in message ... We have a 60 amp 240 volt two pole GE fused disconnect switch in our attic supplying the air handler/auxillary electric heat for one of our heat pump HVAC systems. It is fed from a dedicated 60 amp breaker in the home's load center. That switch has been a nuisance since the house was built about 19 years ago. Every year or so the switch contacts start heating up and will eventually heat the end carp on one of the fuses enough to melt the solder joining the fuse's link to the cap, shutting down things. The overheated fuse usually falls apart when I take it out, as its fiber tube is crisped. I take the switch apart, clean up all the discolored switch parts with a fine file, paint some Kopper-Shield on them and put it all back together with a new fuse. My cleaning fixups last for another year or so and the same contact heating thing repeats. About six years ago I gave up and figured maybe I just had a "bad" disconnect switch, so I bought an same model GE disconnect and just swapped in the guts to avoid having to mess around changing the housing and cable entries. The same switch contact heating problem happened again a year later. The disconnect is in a dry area, and the switch is never thrown except when I have to fix it, so why does this happen? The current draw with the auxiliary heaters on is less than 40 amps, and as I'm using regular quick blow cartridge fuses, I doubt if there's much surge even when those heaters are cold, or the fuses would blow. After a cleanup I've let the auxiliary heaters run for ten minutes and then felt the disconnect switch parts (with the breaker off of course). They feel like they're only a few degrees above ambient then. Is it just that GE fused disconnects are likely to be ****e, or am I possibly overlooking something? Methinks I'll just pick up a non-fused disconnect and next weekend deep six that darned fused GE disconnect I spent an hour cleaning up this morning, when we woke up with no heat. I can't really understand why the installers used a fused disconnect there anyway. I appreciate the need for a disconnect in close proximity to the equipment, but having fuses in it when it's fed from a dedicated breaker of the same rating seems redundant. Am I right about that? Comments? Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" This is Turtle Jeff , These fuse disconnects are stated as rated at 60 amps but if you read the amp draw rating in the data plate with it. You will see it is suppose to be used on amp draws of less than 40 amps. It states that it will handle short time useage of near 60 amps but when put in a contenous amp draw the 40 amps your drawing on it become the max it will handle. I have the Connecuit Electric type I use on condenser outside and they are rated at 60 amps but if you read closely you will see it says contenous use 40 amps is the MAX. it will handle. You just don't run anything at Max. By running this disconnect at 40 amps is like it says on the Lexus LS-400 Maxium operating speed is 161 M.P.H. and then you can run it at that speed and be safe. So if you don't run your car at Max. Speed 160 M.P.H , Don't run your 60 Amp disconnect Rated at Max. Amps 40 Amps. Well now, I'll check the specs and if that's the case it sure makes sense now! And too bad the original installer didn't see it that way too, it would have saved me a lot of nuisance fixups. Thanks, and I hope the 60 amp Aquare-D non-fused plug type disconnect switch I just bough yesterday isnn's similarly rated. G Jeff This is Turtle. No that Square - D breaker looking disconnect is rated above the 40 amps but usely in about 2 to 4 years the breaker will burn inside the breaker and go out and then you can replace it with a real breaker square- D and keep going. A lot of HVAC people don't like them for that call back coming in 2 to 4 years. Now if you replace it now with a real breaker to apply to the application you will not see it down the road. No, the one I bought is the "pull-out" kind. I looked at the one with the "breaker looking" switch in it and decided not to take the risk of its switch contacts fouling up by themselves. The plug-in contacts look pretty robust and feel tighter than a virgin's cooze. I'll swap it in and report back in a year or two. G I'm still scratching my head in amazement that a closed switch with what appears to be adequate ratings located in a benign environment will slowly develop increased contact resistance, but I've seen it and believe it, so it must be so. Again, my apologies for wasting all the bandwith on this simple little problem. It's my engineer's mind dammit, I have an overwhelming desire to learn why things like that happen, I guess it's one of my my retirement hobbies, thoroughly non-cost effective, but fun, like many other hobbies. Jeff TURTLE Do they make a 100A disconnect that just has a pull-out block with 2 cartridge fuses in it? That's what I think I would use if they are available that big. Put in whatever size fuses you actually need to protect the heater, (45A?) or just put 100A fuses in it and let the breaker back in the main panel provide the protection. Bob This is Turtle. Yes they do but your looking at about $68.00 + Tax . It will come with a lever on the out side and spaded type fuses and the fuses are about $8.00 each even being 60 amps to 100 amps sizes. The 60 amp disconnect is the breaking point between commercial and residentiual equipment and the price reflects it. Now this type fuse box / fused type disconnect will run at 90 amps till the cows come home but the 60 amp cheap o will run till the sun goes down. . The standard 60 amp fuse / disconnect $15.00 verses the 100 amp fuse box / fused disconnect at $78.44 is a far cry between them in quality and in price. At about 5 times the cost the public will not go for 5 times the price when Home Depot sells them for $15.00 and the home owner can replace them pretty easy. TURTLE -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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#39
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Duane Bozarth wrote:
Jeff Wisnia wrote: ... I clim(b)ed up and looked at the paper label inside the GE fused disconnect last nnite (Cat #TG3222-MOD6 to be specific). Off at the bottom of the label in type so small I had to work hard to pick it out, it reads, "Contact current not to exceed 80% of fuse rating for other than motor circuits." ... Note that NEC requires no more than 80% of rated amperage for virtually all boxes, irrespective of manufacturer. It's a good rule of thumb that many don't adhere to. Another thing during this thread (that hadn't popped to the fore in my mind until last night for some reason) is that in the attic you may not have adequate (or any to speak of) air flow around the box so that the ambient temperature ratings may not be valid since they're based on "normal" air circulation. If the box is in an area where there isn't a convection path over/around it, it may well have an internal temperature rise well above that you observed w/ the brief open box test you did. Thanks, but I don't think it's likely to be a temperature problem as our attic is quite well vented by continuous louvered vents along the entire length of the soffits at the roof edge overhangs in front and back, and a ridge vent all along the top. Even in the summer when I've been up there it never feels like it's over 100F, and in the winter, like last night It felt like it was down in the 40s. The disconnect is located on a piece of plywood nailed to a couple of vertical 2 by 4s tacked between a ceiling joist and a roof joist and is "in the clear" about 2 feet off the "floor", so convection definitely should do its thing, as long as we don't run low on gravity. G I think the upgrade to a 100 A box would solve the issue plus, perhaps, if there is a restriction around where it is presently mounted, moving it to a more open area couldn't hurt (and just might solve the problem w/o the other box). I'd agree with a 100 amp box, but I'm gonna try the 60 amp Square-D pullout disconnect first. The contacts in it for the plug blades squeeze them from both sides, unlike the switch contacts in the problematic GE fused disconnect I'm wasting so much bandwidth discussing. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "As long as there are final exams, there will be prayer in public schools" |
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Jeff Wisnia wrote:
.... The disconnect is located on a piece of plywood nailed to a couple of vertical 2 by 4s tacked between a ceiling joist and a roof joist and is "in the clear" about 2 feet off the "floor", so convection definitely should do its thing, as long as we don't run low on gravity. G Well, was just a possibility as noted... I'd agree with a 100 amp box, but I'm gonna try the 60 amp Square-D pullout disconnect first. The contacts in it for the plug blades squeeze them from both sides, unlike the switch contacts in the problematic GE fused disconnect I'm wasting so much bandwidth discussing. May well work as well...and what are usenet groups for, anyhow???  |
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