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#1
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Blowing light bulbs
Yeah, I know, not this topic again... But this is getting ridiculous.
I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
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#2
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"Chris Lewis" wrote in message
... Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. Not familiar with BR30 bulbs. Are they incandescent or fluorescent? If incandescent, is it possible that foot traffic from above is causing enough vibration to ruin the bulbs? If fluorescent, never mind.... |
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#3
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Chris Lewis wrote:
Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. you can try installing a dialed dimmer switch. or see if you can find any of those devices that go in the socket that are supposed to extend the life of the bulb, not sure what they do. could it be the room temperature is too low? Soft starting of lights definitely extends the life. -- Respectfully, CL Gilbert |
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#4
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Chris Lewis wrote:
Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. There is a gizmo, looks like a wafer, you can put inside the bulb socket, to limit the surge to the bulbs. I bet it's just a flat resistor, but it might help. |
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#5
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HeyBub wrote:
Chris Lewis wrote: Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. There is a gizmo, looks like a wafer, you can put inside the bulb socket, to limit the surge to the bulbs. I bet it's just a flat resistor, but it might help. IIRC they aren't just resistors, they're thermistors, which have a moderately high resistance when cold, to limit the bulb's turnon surge current. They warm up fast with current flowing through them and drop way down in resistance so that most of the power gets used by the bulb. Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "Truth exists; only falsehood has to be invented." |
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#6
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#7
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Chris Lewis wrote:
Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. Heat, vibration, water and over voltage are common problems for short life. Heat? (are the fixtures rated for 45W or more? Vibration? Anything causing a vibration of the fixtures? Water? Anyway they could have water drip on them; condensation maybe? Over voltage? This is my guess. The power coming into you home could be too high or if you have a floating ground (usually one loose wire, and not always near the lights) that could account for it. Do the lights brighten and dim sometimes? Do you have any aluminum wire anywhere in the house? -- Joseph Meehan Dia duit |
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#8
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In art. , CL (dnoyeB) Gilbert wrote
in part: you can try installing a dialed dimmer switch. or see if you can find any of those devices that go in the socket that are supposed to extend the life of the bulb, not sure what they do. could it be the room temperature is too low? Soft starting of lights definitely extends the life. Usually not much (there are some exceptions), despite lightbulbs typically blowing during a cold start. What usually happens is that cold starts do surprisingly little damage to the filament, while a filament that is approaching end-of-life (due mainly to operating hours and filament temperature during steady operation) becomes unable to survive a cold start a little before becoming unable to survive steady operation. A filament that has suffered uneven evaporation to the extent to become unable to survive a cold start is already in bad shape, and this condition is accelerating at a rate that increases worse than exponentially while the filament is running. Now a bit of specific data: I actually got one of those soft-starting "buttons" to attach to the bottom of a lightbulb to supposedly double its life. I managed to get an indirect reading of voltage drop across the "button" and the lightbulb while the "button" was in place and fully warmed up, and it turns out the "button" dropped enough voltage to dim the lightbulb enough to extend its life 50%. Also: Using the usual rules of lightbulb performance as a function of voltage, light output went down 11% while current consumption (and power consumption, counting watts dissipated in lightbulb and button combined) went down 1.7%. - Don Klipstein ) |
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#9
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In article , Chris Lewis wrote:
Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). I would suspect, as others have mentioned, vibration beating up the filaments while they are hot. In bad cases foot traffic could do this. Also, do people slam doors nearby or dance on the floor above or do children dribble basketballs on the floor above? That can do this! As for a possible solution: Get Philips SLS20 compact fluorescents with the R30 snap-on reflectors. Find an electrical/lighting supply shop that has these. Or find an online place that has these - I believe bulbs.com does. As far as I know, the reflectors can be removed and reattached to other SLS bulbs, so when they wear out you can get just replacement bulbs, which Home Depot has. Philips SLS compact fluorescents are well suited for recessed ceiling fixtures for the 15 and 20 watt versions (not dimmable), and rated as acceptable for such use in the non-dimmable 23 watt version. Most other integral-ballast compact fluorescents, especially of similar and higher wattages, do not fare as well in recessed ceiling fixtures. You may want to try the 19 watt or whatever Feit Electric compact fluorescent floodlight bulb supposedly equal to 85 watt incandescent, (see if it will fit), available at Home Depot. 19-20 watt compact fluorescent with smaller reflector has performance compromised by compact reflector size, so expect equivalence to about 60 watts incandescent wide beam flood, and expect some dependence on using several of these so that their less-well-defined beams merge into each other. - Don Klipstein ) |
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#10
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Joe...
Interesting possibilities to ponder......... How does aluminum account for overvoltage? If it has an inherent higher resistance, I would expect the opposite. What about a floating ground? It would have a lower differential to the mains. Please qualify how this would work. Thanks Les KA9GLW I agree with the overvoltage as a consideration, but I can't see how this could happen in practice. My other thought is that these bulbs are not the tungsten variety, but the halogen type. It's known that the ion exchange between the halogen envelope, the gases and the filament are tuned to work at specific temperatures. If you try to alter the optimum operating temperature, they fail much quicker. So, don't dim halogen bulbs. It doesn't extend their life, but shortens it. A soft start would be an exception, I'm sure. |
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#11
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Blowing lightbulbs is a felony.
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#12
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Don Klipstein wrote:
In art. , CL (dnoyeB) Gilbert wrote in part: you can try installing a dialed dimmer switch. or see if you can find any of those devices that go in the socket that are supposed to extend the life of the bulb, not sure what they do. could it be the room temperature is too low? Soft starting of lights definitely extends the life. Usually not much (there are some exceptions), despite lightbulbs typically blowing during a cold start. What usually happens is that cold starts do surprisingly little damage to the filament, while a filament that is approaching end-of-life (due mainly to operating hours and filament temperature during steady operation) becomes unable to survive a cold start a little before becoming unable to survive steady operation. A filament that has suffered uneven evaporation to the extent to become unable to survive a cold start is already in bad shape, and this condition is accelerating at a rate that increases worse than exponentially while the filament is running. yes. Its kind of playing a game. Like using something thats broken, but using it very gently so as to keep using it... Now a bit of specific data: I actually got one of those soft-starting "buttons" to attach to the bottom of a lightbulb to supposedly double its life. I managed to get an indirect reading of voltage drop across the "button" and the lightbulb while the "button" was in place and fully warmed up, and it turns out the "button" dropped enough voltage to dim the lightbulb enough to extend its life 50%. Also: Using the usual rules of lightbulb performance as a function of voltage, light output went down 11% while current consumption (and power consumption, counting watts dissipated in lightbulb and button combined) went down 1.7%. - Don Klipstein ) Nice. We do the same thing to car headlamps when possible. -- Respectfully, CL Gilbert |
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#13
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Have you checked the voltage? You might have excessive voltage or a loose
neutral. Probably not, but if you haven't checked... |
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#14
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Years ago I had a goose neck lamp over the work bench. Every time I turned
on the grinder, the Phillips light bulb would blow. finally I tried a GE, which lasted a lot longer. Try a different brand of bulb, they are not all created equal. -- Christopher A. Young Learn more about Jesus www.lds.org www.mormons.com "Chris Lewis" wrote in message ... Yeah, I know, not this topic again... But this is getting ridiculous. I have a string of about 6 pot fixtures in the basement with BR30 bulbs. The fixtures are switched by a pair of 3 way switches. The fixtures are open to the air - the ceiling hasn't been drywalled (yet). The bulbs are burning out at a very high rate. Within a week of getting them all working again, at least one goes out, within another month, usually all of them are dead. As far as I can remember, these have all been Sylvanias, some "extended lifetime" (hah!). Most of the time, a bulb expires when we "flick" (as opposed to "sloowwly presssss" ;-) one of the threeways. The threeway switches are relatively newish decora type switches. Probably cheapies - I'll bet they bounce a lot. I'm looking for real-world experience here - has anybody solved lamp burnouts like this by replacing the switches? Are there line filters for this sort of purpose? I want to exhaust those possibilities before going on an expensive quest for more expensive bulbs. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
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#15
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les wrote:
Joe... Interesting possibilities to ponder......... How does aluminum account for overvoltage? If it has an inherent higher resistance, The power to your home is supplied at 240V. It is split 120V on either side of the neutral. The neutral is connected to the ground, but it is not a ground. Each 120V circuit is one one or the other side of the neutral. If you had two 120V circuits with exactly the same load (say 5 100W lamps) then the they would be balanced and current would flow only on the two hot wires and nothing on the neutral leaving your home (you have three wires and maybe a ground coming into your home.) however if one of the lamps went out, you would have about one amp more going through one side than the other so the difference would flow through the neutral OK I am getting to your question. With aluminum wire, connections tend to get flaky so it is possible that the neutral may not make good connection so the set of 5 good lamps would get less current and be a little dimmer and the side with 4 good lamps would be brighter. If you have aluminum wire coming into your home from the street, that's OK they use special designed fittings to eliminate the problem, but if you have it inside your walls running to outlets, it can be a hazard because of the bad connections. I would expect the opposite. What about a floating ground? It would have a lower differential to the mains. Please qualify how this would work. Thanks Les KA9GLW I agree with the overvoltage as a consideration, but I can't see how this could happen in practice. My other thought is that these bulbs are not the tungsten variety, but the halogen type. It's known that the ion exchange between the halogen envelope, the gases and the filament are tuned to work at specific temperatures. If you try to alter the optimum operating temperature, they fail much quicker. So, don't dim halogen bulbs. It doesn't extend their life, but shortens it. A soft start would be an exception, I'm sure. -- Joseph Meehan Dia duit |
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#16
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Matt wrote:
Blowing lightbulbs is a felony. So is screwing in one: http://home.comcast.net/~jwisnia18/temp/screwing.gif Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "Truth exists; only falsehood has to be invented." |
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#18
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Random responses:
These are brand-new (less than a year old) ceiling pot fixtures. A "standard" HD brand of some sort. Cheapies, but reasonably well built. Rated at 100W I believe. BR30s are medium size incandescent flood lights, 60W apiece - the fixtures are designed specifically for this size. The halogen equivalent is "PAR30" IIRC. So heat is unlikely to be a problem. We haven't even installed the fixture bezels yet. Vibration is certainly a possibility, but we're aware of it (I wrote the FAQ on that! ;-), and some of the lights that are dying aren't anywhere near floor space likely to have much vibration. CFs on the same area (in previous ceiling mounted J-boxes, same switches) also _seemed_ to have a relatively shortened lifespan. There is no aluminum on (or upstream) of this circuit. The only aluminum is a subpanel feed to the garage. No, we're not having dimming/brightening problems. Many other bulbs in the house have more than adequate lifetimes (ie: 10 year+ on some reasonably well used flood lights). So it's not an overall voltage problem. As we've not had a lot of luck with CFs on this circuit already, I'm hesitant about going for them until I understand what's happening. [Our kitchen ceiling lights also have similar problems, despite being on a dimmer.] I should check the voltages on this circuit just in case. A pair of new switches is probably a good idea too. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
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#19
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"Chris Lewis" wrote in message
... Vibration is certainly a possibility, but we're aware of it (I wrote the FAQ on that! ;-), and some of the lights that are dying aren't anywhere near floor space likely to have much vibration. CFs on the same area (in previous ceiling mounted J-boxes, same switches) also _seemed_ to have a relatively shortened lifespan. In case you want to spend a few bucks to prove or disprove the vibration theory, Home Depot carries an incandescent bulb by Philips, specifically labeled for use in ceiling fans. My fan was blowing bulbs almost weekly due to a nasty vibration transmitted through the ceiling from the monster of an exhaust fan in the bathroom 20 feet away. (I'll be dealing with that later this summer). I switched to the Philips bulbs - problem gone. They're 40 watt bulbs, shaped like normal lamp bulbs, but maybe 30-40% smaller in size. Might be worth a shot. |
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#20
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According to les :
The power to your home is supplied at 240V. It is split 120V on either side of the neutral. The neutral is connected to the ground, but it is not a ground. Each 120V circuit is one one or the other side of the neutral. I never thought about this before, but in the 2 phase system as you [Technically, it's not 2 phase. It's simply a center-tapped transformer winding.] describe, where does the transformation occur? On the pole down the street? Yes. If so, the utility company has me and many other costumers experiencing possible imbalances due to the communal sharing. How do they account for these potential problems? (no pun intended) I uinderstand your explaination, but I think in a low impedance system as the power grid, you would need a large current difference in the 2 legs to see anything measureable. Does it really happen in the real world? I'm aware of brown-outs, but this isn't it.......... If the neutral is not making a solid connection back to the center tap of the transformer, the apparent neutral-real ground voltage can be quite extreme, resulting in one leg of the feed being significantly lower than 120V and the other much higher. It simply becomes a voltage divider between whatever devices you have attached to the two legs. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
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#21
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The power to your home is supplied at 240V. It is split 120V on
either side of the neutral. The neutral is connected to the ground, but it is not a ground. Each 120V circuit is one one or the other side of the neutral. Joe... I never thought about this before, but in the 2 phase system as you describe, where does the transformation occur? On the pole down the street? If so, the utility company has me and many other costumers experiencing possible imbalances due to the communal sharing. How do they account for these potential problems? (no pun intended) I uinderstand your explaination, but I think in a low impedance system as the power grid, you would need a large current difference in the 2 legs to see anything measureable. Does it really happen in the real world? I'm aware of brown-outs, but this isn't it.......... (and speaking of grounds, what defines a ground? That's a relative thing) |
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#22
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Don Klipstein wrote:
In art. , CL (dnoyeB) Gilbert wrote in part: you can try installing a dialed dimmer switch. or see if you can find any of those devices that go in the socket that are supposed to extend the life of the bulb, not sure what they do. could it be the room temperature is too low? Soft starting of lights definitely extends the life. Usually not much (there are some exceptions), despite lightbulbs typically blowing during a cold start. What usually happens is that cold starts do surprisingly little damage to the filament, while a filament that is approaching end-of-life (due mainly to operating hours and filament temperature during steady operation) becomes unable to survive a cold start a little before becoming unable to survive steady operation. A filament that has suffered uneven evaporation to the extent to become unable to survive a cold start is already in bad shape, and this condition is accelerating at a rate that increases worse than exponentially while the filament is running. Now a bit of specific data: I actually got one of those soft-starting "buttons" to attach to the bottom of a lightbulb to supposedly double its life. I managed to get an indirect reading of voltage drop across the "button" and the lightbulb while the "button" was in place and fully warmed up, and it turns out the "button" dropped enough voltage to dim the lightbulb enough to extend its life 50%. Also: Using the usual rules of lightbulb performance as a function of voltage, light output went down 11% while current consumption (and power consumption, counting watts dissipated in lightbulb and button combined) went down 1.7%. - Don Klipstein ) Lots of nice info there. Thanks. I am wondering what the effective voltage drop would be for a dimmer that is full on. It has been my experience from work with tungsten heating coils in a vacuum system that unused tungsten can be bent into small radius turns, BUT, after it has been used into the dull red heat range the same wire will break if that same bending is attempted. I guess it has to do with annealed or not annealed and work hardening, but I can never remember how that goes! My point is that a USED bulb filament is mechanically fragile, AND when standard service bulbs are turned on with a switch, there are MECHANICAL forces due to the start up of magnetic/electric fields. These mechanical forces on the filament may be demonstrated by the ringing sound some filaments will make when a dimmer is set low. Sound is due to a mechanical phenomenon, so that would mean the filament is vibrating! I continue to be convinced that using an up/down dimmer (one with no abrupt on/off) slows down bulb burn out, and that mechanical actions will also do it for bulbs. For example, rough service bulbs last longer in mechanically rough service, and if we look at the guts of such bulbs, we see extra filament supports which minimize vibration. --Phil -- Phil Munro Dept of Electrical & Computer Engin Youngstown State University Youngstown, Ohio 44555 ------------ And now a word from our sponsor ------------------ For a quality usenet news server, try DNEWS, easy to install, fast, efficient and reliable. For home servers or carrier class installations with millions of users it will allow you to grow! ---- See http://netwinsite.com/sponsor/sponsor_dnews.htm ---- |
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#23
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"Phil Munro" wrote in message
... For example, rough service bulbs last longer in mechanically rough service, and if we look at the guts of such bulbs, we see extra filament supports which minimize vibration. --Phil I've never found a rough service bulb whose light color wasn't ugly. I wonder why? |
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#24
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Doug Kanter wrote:
"Phil Munro" wrote in message ... For example, rough service bulbs last longer in mechanically rough service, and if we look at the guts of such bulbs, we see extra filament supports which minimize vibration. --Phil I've never found a rough service bulb whose light color wasn't ugly. I wonder why? I use clear glass fan bulbs (which are a form of rough service, I think) and some "rough service" bulbs for a trouble light. I have not noticed "ugly" color. What does "ugly" mean? --Phil -- Phil Munro Dept of Electrical & Computer Engin Youngstown State University Youngstown, Ohio 44555 |
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#25
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"Phil Munro" wrote in message ... Doug Kanter wrote: "Phil Munro" wrote in message ... For example, rough service bulbs last longer in mechanically rough service, and if we look at the guts of such bulbs, we see extra filament supports which minimize vibration. --Phil I've never found a rough service bulb whose light color wasn't ugly. I wonder why? I use clear glass fan bulbs (which are a form of rough service, I think) and some "rough service" bulbs for a trouble light. I have not noticed "ugly" color. What does "ugly" mean? --Phil Other than some Philips frosted fan bulbs I mentioned elsewhere in this thread, my experience with rough service bulbs has been those labeled as "Good for trouble lights". Weird, overly warm color, more so than your run-of-the-mill light bulbs. Doesn't matter so much in a trouble light, but there have been some other instances over the years when I could've used them, in basement fixtures, for instance, where foot traffic above seemed to be causing early bulb failure. |
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#26
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According to Harry :7501:
Considering the money youare spending in bulbs, it would seem to me that it would be a lot less expensive to just install a proper lighting system. Standard recessed light fixtures and the bulbs that they're designed for installed as per instructions and electrical code aren't "proper"? It is all so easy now: they have things that you can pinch and squeeze onto a wire running along the beams. "Pinch and squeeze" 120V permanent fixture wiring? Proper? Good gracious me. Not. As far as running a wire, just do what it is that you are good at: use your imagination and just "N"-rig it . . . I'm quite good at running wire, thank you. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
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#27
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Doug Kanter wrote:
"Phil Munro" wrote in message What does "ugly" mean? --Phil Other than some Philips frosted fan bulbs I mentioned elsewhere in this thread, my experience with rough service bulbs has been those labeled as "Good for trouble lights". Weird, overly warm color, more so than your run-of-the-mill light bulbs. Looking at 75W bulbs, the rough service bulb is 62% of the light output of a normal bulb. Part of this is losses from more filament supports. But they probably run the filament at a lower temperature to make it more shock resistant. Lower temperature shifts the spectrum toward the red. Bud-- |
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#28
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In article , Chris Lewis wrote:
Random responses: These are brand-new (less than a year old) ceiling pot fixtures. A "standard" HD brand of some sort. Cheapies, but reasonably well built. Rated at 100W I believe. BR30s are medium size incandescent flood lights, 60W apiece - the fixtures are designed specifically for this size. The halogen equivalent is "PAR30" IIRC. So heat is unlikely to be a problem. We haven't even installed the fixture bezels yet. Vibration is certainly a possibility, but we're aware of it (I wrote the FAQ on that! ;-), and some of the lights that are dying aren't anywhere near floor space likely to have much vibration. CFs on the same area (in previous ceiling mounted J-boxes, same switches) also _seemed_ to have a relatively shortened lifespan. Fixtures as described above are notoriously hard on compact fluorescents. (Less of a problem for most CFLs 13 watts or less, as well as Philips SLS excluding versions 25 watts or more or dimmable). So I suspect rough heat situation for early failure of compact fluorescents, and fair-good chance of a different reason for early failure of incandescents - most likely bad brand or bad lot of bulbs, after that significantly high line voltage or vibration. There is no aluminum on (or upstream) of this circuit. The only aluminum is a subpanel feed to the garage. No, we're not having dimming/brightening problems. Many other bulbs in the house have more than adequate lifetimes (ie: 10 year+ on some reasonably well used flood lights). So it's not an overall voltage problem. As we've not had a lot of luck with CFs on this circuit already, I'm hesitant about going for them until I understand what's happening. [Our kitchen ceiling lights also have similar problems, despite being on a dimmer.] If you are using the dimmer as a soft-starting means, please be aware that soft-starting usually increases incandescent lifetime only a little. Some incandescents even suffer vibration problems from the spiky current waveforms when dimmed by usual dimmers, to an extent such that dimming only slightly extends their lives. (Most incandescents have major life extension from dimming, although with energy efficiency decreasing badly enough for cost of achieving a given level of lighting to actually increase.) Most halogens have an aging mechanism slowed only a little by dimming and a few halogens have contaminants that dominate and wreak havoc when major dimming is done. I should check the voltages on this circuit just in case. A pair of new switches is probably a good idea too. - Don Klipstein ) |
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In article , Phil Munro wrote:
Don Klipstein wrote: In art. , CL (dnoyeB) Gilbert wrote in part: you can try installing a dialed dimmer switch. or see if you can find any of those devices that go in the socket that are supposed to extend the life of the bulb, not sure what they do. could it be the room temperature is too low? Soft starting of lights definitely extends the life. Usually not much (there are some exceptions), despite lightbulbs typically blowing during a cold start. What usually happens is that cold starts do surprisingly little damage to the filament, while a filament that is approaching end-of-life (due mainly to operating hours and filament temperature during steady operation) becomes unable to survive a cold start a little before becoming unable to survive steady operation. A filament that has suffered uneven evaporation to the extent to become unable to survive a cold start is already in bad shape, and this condition is accelerating at a rate that increases worse than exponentially while the filament is running. Now a bit of specific data: I actually got one of those soft-starting "buttons" to attach to the bottom of a lightbulb to supposedly double its life. I managed to get an indirect reading of voltage drop across the "button" and the lightbulb while the "button" was in place and fully warmed up, and it turns out the "button" dropped enough voltage to dim the lightbulb enough to extend its life 50%. Also: Using the usual rules of lightbulb performance as a function of voltage, light output went down 11% while current consumption (and power consumption, counting watts dissipated in lightbulb and button combined) went down 1.7%. - Don Klipstein ) Lots of nice info there. Thanks. I am wondering what the effective voltage drop would be for a dimmer that is full on. It has been my experience from work with tungsten heating coils in a vacuum system that unused tungsten can be bent into small radius turns, BUT, after it has been used into the dull red heat range the same wire will break if that same bending is attempted. I guess it has to do with annealed or not annealed and work hardening, but I can never remember how that goes! My point is that a USED bulb filament is mechanically fragile, AND when standard service bulbs are turned on with a switch, there are MECHANICAL forces due to the start up of magnetic/electric fields. These mechanical forces on the filament may be demonstrated by the ringing sound some filaments will make when a dimmer is set low. Sound is due to a mechanical phenomenon, so that would mean the filament is vibrating! Outright true, but for most lightbulbs this stress is within the "endurance limit" (threshold of causing metal fatigue), and less than the stress of having people dance or dribble basketballs on the floor above or slamming nearby doors. And yes I do know that a lightbulb experiencing a cold start can have its filament mechanically jolt enough to produce a "ping" sound that is often audible within a foot or two away. NOTE - the filament is much weaker when hot, and the main mechanical stress of a cold start occurs when the filament is not so hot, and much stronger than a hot filament whether it is ductile or brittle. I continue to be convinced that using an up/down dimmer (one with no abrupt on/off) slows down bulb burn out, and that mechanical actions will also do it for bulbs. For example, rough service bulbs last longer in mechanically rough service, and if we look at the guts of such bulbs, we see extra filament supports which minimize vibration. --Phil Most dimmers when turned all the way up will reduce RMS voltage to a lightbulb roughly 2-3 percent, and that reduces light output about 3 times that and can account for a life extension of 20-40%. In general, "rough service" bulbs have much longer life expectancy than "standard" bulbs even where there is no damaging vibration present due to the filament being designed to run cooler, since most such bulbs are used where labor has to be paid to replace them. Also, they are less efficient to such an extent that a 60 watt "standard" bulb usually outshines a 75 watt "vibration resistant" or "rough duty" one. Over 1,000 operating hours, 15 watts of electricity usually costs more than a lightbulb does. -- Phil Munro - Don Klipstein ) |
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