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#1
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Detecting first recepticle on a circuit
Is there a simple way to figure out which is the first recepticle on a
circuit? I have an older house - the two upstairs rooms are on the same circuit and are not grouned. Id like to add a GFCI plug on the first recepticle on that circuit, so every recepticle downstream is protected. The brute force method would be to guess which recepticle is the first, remove the outgoing wires, and test every other outlet for power - rinse (hook back up the wires), repeat, until ive found the recepticle that has power and all the others that dont. However this will take awhile - most arent easily accessible - behind furnitire, beds etc. I have at my disposal the standard home repair tools - volt meter, etc. Thanks! |
#2
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Detecting first recepticle on a circuit
Why don't you just put in a GFCI breaker for the whole circuit to
ensure it is protected. |
#3
Posted to alt.home.repair,sci.electronics.design,sci.electronics.misc
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Detecting first recepticle on a circuit
canadian_woodworker
Is there a simple way to figure out which is the first recepticle on a circuit? I have an older house - the two upstairs rooms are on the same circuit and are not grouned. Id like to add a GFCI plug on the first recepticle on that circuit, so every recepticle downstream is protected. The brute force method would be to guess which recepticle is the first, remove the outgoing wires, and test every other outlet for power - rinse (hook back up the wires), repeat, until ive found the recepticle that has power and all the others that dont. However this will take awhile - most arent easily accessible - behind furnitire, beds etc. I have at my disposal the standard home repair tools - volt meter, etc. Nehmo - I don't know exactly how to do it in practice, but in theory… 1. Unplug everything on the circuit. At the circuit breaker box, with the breaker off, connect what would have been the hot wire of the circuit to the neutral. Leave the neutral connected normally. Measure between one slot and the other at each receptacle. At each receptacle, the measurement of the resistance and inductance will be different. They will be lowest at the first, and highest at the last. 14 gauge wire only has a resistance of 2.6 ohms per 1,000 feet, so the difference in resistance will be difficult to measure. But the inductance should be substantially different at each receptacle. At higher frequencies, the measurement should be easy. Or 2. Get something that detects AC _current_ in a wire without electrically connecting to the wire. Perhaps a pick-up coil attached to an amplifier or perhaps a large coil simply connected to an earphone. I'm not used to the commercial non-contact detectors, but one of them would work. You want something that makes a different indication for a current flowing wire and just a hot wire. After you have your detection tool, experiment with it. Learn to detect a current-carrying wire. With the circuit breaker on, plug-in a high-wattage lamp in what you suspect to be the first receptacle. You should not be able to detect current moving through the wires at any other receptacle. If you detect current at a receptacle, it's at a position before the lamp receptacle. Unplug the lamp and plug it in what you suspect to be the last receptacle. You should be able to detect current at every receptacle. Note I'm making a distinction between a receptacle with current going through the wires connected to it and a receptacle that's just hot. All of them should be hot. The electromagnetic field will be much stronger around a current carrying wire. Or 3. Get a really high-wattage load, perhaps a big electric heater, something with a high enough wattage to heat its supply wires detectably - but not dangerously. Use the same system as the current detector. Plug in the load at the (believed) last receptacle. Check the earlier receptacles for warm wires. You get the idea. 4. Fire the circuit up with DC (use a rectifier by the circuit breaker box). Put a low-resistance load on the circuit at some receptacle. With a sensitive voltmeter, measure between a hot slot of one receptacle and the hot slot of another. The existence and the polarity of this tiny voltage drop will show the relative position of the receptacles. If you draw a diagram, you'll understand. You could do this with the regular AC too, but you wouldn't get the polarity info. You still could figure out which receptacle is first. You're testing for a voltage drop across a load, which in this case is just a piece of wire between receptacles. The voltage drop will not be much. [I crossposted] -- (||) Nehmo (||) |
#4
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Detecting first recepticle on a circuit
wrote in message oups.com... : Is there a simple way to figure out which is the first recepticle on a : circuit? I have an older house - the two upstairs rooms are on the same : circuit and are not grouned. Id like to add a GFCI plug on the first : recepticle on that circuit, so every recepticle downstream is : protected. : : The brute force method would be to guess which recepticle is the first, : remove the outgoing wires, and test every other outlet for power - : rinse (hook back up the wires), repeat, until ive found the recepticle : that has power and all the others that dont. However this will take : awhile - most arent easily accessible - behind furnitire, beds etc. : : I have at my disposal the standard home repair tools - volt meter, etc. : : Thanks! : That's probably the onlyh accurate, positive way to do it though. Usually it'll be the box that is the least wire distance from the breaker box, so some logic might help as opposed to a WAG at where to start. If you can see much of the wiring leaving the breaker box, that might give a hint, too; depends. Pop |
#5
Posted to alt.home.repair,sci.electronics.design,sci.electronics.misc
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Detecting first recepticle on a circuit
from google on GFCI circuit breaker
For broad protection, GFCI circuit breakers may be added in many panels of older homes to replace ordinary circuit breaker. For homes protected by fuses, ... http://doityourself.com/electric/gfci.htm |
#6
Posted to alt.home.repair,sci.electronics.design,sci.electronics.misc
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Detecting first recepticle on a circuit
Yea, ive read that page before.
afaik, those breakers are pretty expensive. But ill check today and possibly pick one up. Thanks for the comments all. Nehmo - your post alluded to a method I had considered, but im not skilled enough to know exactly what to do What you say makes sense, but I think ill either go with a breaker, or the method I talked abut. Thanks all for comments. |
#7
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Detecting first recepticle on a circuit
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#8
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Detecting first recepticle on a circuit
I'm pretty unsophisticated- barely use meters- here's what I'd do.
First, just try to trace the likely wire route by seeing where circuit exits panel, get up in attic and see if I can see where run drops down etc. Taking guess from this which is first receptacle in circuit- after turning off power- and testing to make sure it's off!- pull out this recep and disconnect black wires, then reconnect this recep, but not run which continues to rest of circuit- cap loose wire. Turn power back on and test to see if this recep is live, but rest of circuit dead. Of course if it is dead you probably reconnected run to rest of circuit and capped line from panel. This could be laborious if your guesses are wrong/ if it is difficult to trace wire route. Usually it is not that hard, but that does depend on how your house is wired/ whether attic has decking etc. It is easier if you begin by testing to see exactly which receps are on that circuit- turn it off and test them all to see which live/dead. |
#9
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Detecting first recepticle on a circuit
GFCI breaker to fir my panel up here in canada is $115 bucks.
The recepticle is 15 bucks. Gonna go that route Thanks for responses all. |
#11
Posted to alt.home.repair,sci.electronics.design,sci.electronics.misc
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Detecting first recepticle on a circuit
On Sun, 12 Feb 2006 09:43:39 GMT, "Nehmo Sergheyev"
wrote: canadian_woodworker Is there a simple way to figure out which is the first recepticle on a circuit? I have an older house - the two upstairs rooms are on the same circuit and are not grouned. Id like to add a GFCI plug on the first recepticle on that circuit, so every recepticle downstream is protected. The brute force method would be to guess which recepticle is the first, remove the outgoing wires, and test every other outlet for power - rinse (hook back up the wires), repeat, until ive found the recepticle that has power and all the others that dont. However this will take awhile - most arent easily accessible - behind furnitire, beds etc. I have at my disposal the standard home repair tools - volt meter, etc. Nehmo - I don't know exactly how to do it in practice, but in theory… 1. Unplug everything on the circuit. At the circuit breaker box, with the breaker off, connect what would have been the hot wire of the circuit to the neutral. Leave the neutral connected normally. Measure between one slot and the other at each receptacle. At each receptacle, the measurement of the resistance and inductance will be different. They will be lowest at the first, and highest at the last. 14 gauge wire only has a resistance of 2.6 ohms per 1,000 feet, so the difference in resistance will be difficult to measure. But the inductance should be substantially different at each receptacle. At higher frequencies, the measurement should be easy. Or 2. Get something that detects AC _current_ in a wire without electrically connecting to the wire. Perhaps a pick-up coil attached to an amplifier or perhaps a large coil simply connected to an earphone. I'm not used to the commercial non-contact detectors, but one of them would work. You want something that makes a different indication for a current flowing wire and just a hot wire. After you have your detection tool, experiment with it. Learn to detect a current-carrying wire. With the circuit breaker on, plug-in a high-wattage lamp in what you suspect to be the first receptacle. You should not be able to detect current moving through the wires at any other receptacle. If you detect current at a receptacle, it's at a position before the lamp receptacle. Unplug the lamp and plug it in what you suspect to be the last receptacle. You should be able to detect current at every receptacle. Note I'm making a distinction between a receptacle with current going through the wires connected to it and a receptacle that's just hot. All of them should be hot. The electromagnetic field will be much stronger around a current carrying wire. Or 3. Get a really high-wattage load, perhaps a big electric heater, something with a high enough wattage to heat its supply wires detectably - but not dangerously. Use the same system as the current detector. Plug in the load at the (believed) last receptacle. Check the earlier receptacles for warm wires. You get the idea. 4. Fire the circuit up with DC (use a rectifier by the circuit breaker box). Put a low-resistance load on the circuit at some receptacle. With a sensitive voltmeter, measure between a hot slot of one receptacle and the hot slot of another. The existence and the polarity of this tiny voltage drop will show the relative position of the receptacles. If you draw a diagram, you'll understand. You could do this with the regular AC too, but you wouldn't get the polarity info. You still could figure out which receptacle is first. You're testing for a voltage drop across a load, which in this case is just a piece of wire between receptacles. The voltage drop will not be much. [I crossposted] If you go to RatShack and buy one of their little amplified speaker boxes (looks like an old transistor radio) and a telephone pickup coil, that combo can ge used to hear 60 Hz magnetic fields near wires. So connect some load gadget to the various outlets one at a time. Something that has nasty current harmonics, like a PC or a tv set, is best... makes the current distinct and more audible. Now you can trace the wires in the walls and figure where the current is going. You may wish to kill other breakers in the house, or have somebody cycle your test load, if things get confusing. John |
#12
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Detecting first recepticle on a circuit
Great idea guys re GFCI right at the panel..
I think I might have to go this route anyway. Ive done about half the recepticles - Im confused because each recepticle is at the end of the line - ie wire comes in, but not out. Becasue of this im guessing that there is a central junction box (es) in the attic or ceiling with drops down to each recepticle. As an fyi - there are hardwired ceiling lights on the circuit as well, although none of the recepticles are switched (they are always live). Many people have suggested getting in the attic. I'm going to try this, but its not going to be that easy. My house is a 1.5 story and the attic is very small - only a couple feet in the best of places, with lots of fiberglass - so mucking around in there will not be pleasent. Couple questions: 1) If I do as suggested and put the GFCI by the panel - will each recepticle be covered if its like I describe above? I can visualize quite easily a series of recepticles with the first being a GFCI and how they would all be covered. However in my case it seems a bit more complicated - ie lights, a junction box spreading to each recepticle, etc. Would this till be ok? Is there any situation where putting a GFCI as the first recpeticle on a circuit would NOT protect ones downstream? 2) Once Ive hooked up the GFCI, is there any way to CONFIRM each recepticle is covered? Ie something i can safely do to try and trip the GFCI (and something safe incase its not on the same circuit as the GFCI). Hopefully what ive said here makes sense. Thanks for the responses all, very helfull. |
#13
Posted to alt.home.repair,sci.electronics.design,sci.electronics.misc
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Detecting first recepticle on a circuit
canadian_woodworker
Is there a simple way to figure out which is the first recepticle on a circuit? I have an older house - the two upstairs rooms are on the same circuit and are not grouned. Id like to add a GFCI plug on the first recepticle on that circuit, so every recepticle downstream is protected. Dudnt work that way- it is qwite posble there is no furst recept-icle. Put in a brak-er. |
#14
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Detecting first recepticle on a circuit
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#15
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Detecting first recepticle on a circuit
" You also want to make sure that you do _not_ have a ground connection
between any of the downstream outlets. It's possible that the ground is hidden or that BX cable was used. " Thanks for your responses Volts500. It is NOT knob and tube from everything Ive seen so far. Can you elaborate a little on what you mean by " make sure you do not have a ground connection between any downstream outlets ". About half of the outlets have NO ground (not even to the box). The other half use a newer cable and are grounded to the box. That ground is connected to the outgoing ground as well which I presume leads to the next outlet. However when I test the outlets with a tester, it reads "open ground" - ie not grounded back to the panel. Are you saying: 1) Remove the outlet to ground connection for each outlet? Ie dont hookup a ground to the outlet? If so, what should I do with that ground wire? Cap it off? Should it be hooked to the junction box? 2) Or something else? Also Could you explain why I _dont_ want a ground connection between any of the downstream outlets? Much thanks. |
#16
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Detecting first recepticle on a circuit
"Should it be hooked to the junction box?"
Opps - I didnt mean "junction" there. I just meant to the actual box obviously. |
#17
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Detecting first recepticle on a circuit
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#18
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Detecting first recepticle on a circuit
canadian_woodworker -
GFCI breaker to fir my panel up here in canada is $115 bucks. The recepticle is 15 bucks. Nehmo - The problem with GFCIs is that they're prone to naissance trips. Usually it's inconvenient to walk all the way to the circuit breaker panel to investigate the condition of the GFCI. A better location is right at the receptacle. And to aid the troubleshooting, a GFCI equipped with an indicator light is helpful http://snipurl.com/mhtb . The best arrangement is to have a GFCI at every receptacle in the protected area. In that way, when a GFCI trips, the power interruption is limited to one duplex receptacle. -- (||) Nehmo (||) |
#19
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Detecting first recepticle on a circuit
Sorry, I mean *nuisance*-trips.
-- (||) Nehmo (||) |
#20
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Detecting first recepticle on a circuit
Sorry, I mean *nuisance*-trips.
-- (||) Nehmo (||) |
#21
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Detecting first recepticle on a circuit
.. You also want to make sure that you do _not_ have a ground connection between any of the downstream outlets. It's possible that the ground is hidden or that BX cable was used. I thought GFI's operation had nothing to do with the ground. It trips when it detects a current imbalance between the hot and neutral, regardless if theres a ground or not. I could be wrong though. |
#22
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Detecting first recepticle on a circuit
According to Nehmo :
canadian_woodworker - GFCI breaker to fir my panel up here in canada is $115 bucks. The recepticle is 15 bucks. Nehmo - The problem with GFCIs is that they're prone to naissance trips. Usually it's inconvenient to walk all the way to the circuit breaker panel to investigate the condition of the GFCI. A better location is right at the receptacle. And to aid the troubleshooting, a GFCI equipped with an indicator light is helpful http://snipurl.com/mhtb . The best arrangement is to have a GFCI at every receptacle in the protected area. In that way, when a GFCI trips, the power interruption is limited to one duplex receptacle. I think that most people would find that GFCI's don't false trip very often. If at all. I've never had one of mine trip when it wasn't clear it _probably_ had a good reason. False trips are suggestive of electrical boxes getting damp, bad extension cords, or oddities in old wiring (intermittent neutral-ground shorts) etc. By putting in more GFCIs, you're increasing your probabilities of GFCI failure _and_ false tripping. I'll bet that if you did a good sized survey, you'll find _more_ trouble (including out-and-out GFCI failure) if you put an GFCI in every receptacle box than you would with a judiciously placed single GFCI outlet (or breaker). -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
#23
Posted to alt.home.repair,sci.electronics.design,sci.electronics.misc,sci.electronics.basics
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Detecting first recepticle on a circuit
[crossposted, s.e.d dropped from followups]
On Sun, 12 Feb 2006 07:38:58 -0800, canadian_woodworker wrote: Yea, ive read that page before. afaik, those breakers are pretty expensive. But ill check today and possibly pick one up. Thanks for the comments all. Nehmo - your post alluded to a method I had considered, but im not skilled enough to know exactly what to do What you say makes sense, but I think ill either go with a breaker, or the method I talked abut. Thanks all for comments. Well, as long as I have your attention, it makes absolutely no difference whatsoever which outlet on a main line has a GFCI - each one only protects itself and what's plugged into it, and couldn't care less what's happening downstream: [view in fixed font, with wrap off] .. .. Mains Hot -------+-------------+-------------+ .. Mains Neut. -----|--+----------|--+----------|--+ .. | | | | | | .. ------ ------ ------ .. | GFCI | | GFCI | | GFCI | .. ------ ------ ------ .. P.C P.C P.C Where "P.C" means "Protected Circuit". What has been suggested, (sorry, don't remember by whom - jalegris?) is to use a GFCI circuit breaker, which goes on the left: .. .. ------- .. Mains Hot --| GFCI |----+-------------+-------------+ .. Mains Neut.--| C.B. |----|--+----------|--+----------|--+ .. ------- | | | | | | .. Ordinary Ordinary Ordinary .. Outlet Outlet Outlet That's "on the left" in my attempt at a diagram - in real life, it goes in the breaker panel. Or, of course, you could upgrade your wiring - it will increase the resale value of the house considerably! :-) Good Luck! Rich |
#24
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Detecting first recepticle on a circuit
Rich,
That's not exactly true. The GFCI receptacles have a LINE input and and LOAD output. Any receptacles connected to the LOAD output terminals of the GFCI are also protected circuits. |
#25
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Detecting first recepticle on a circuit
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#26
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Detecting first recepticle on a circuit
In Canada, at least, it CAN make a difference depending on where you
put the GFCI outlet - it has input and output terminals. By connecting it as the first in a chain you can protect all the other downstream outlets. That's what the OP is trying to do. Of course, you could put GFCI's on every outlet, but it's overkill. Or should I say underkill? -- Joe Legris |
#27
Posted to alt.home.repair,sci.electronics.misc,sci.electronics.basics
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Detecting first recepticle on a circuit
Rich Grise wrote:
[crossposted, s.e.d dropped from followups] On Sun, 12 Feb 2006 07:38:58 -0800, canadian_woodworker wrote: Yea, ive read that page before. afaik, those breakers are pretty expensive. But ill check today and possibly pick one up. Thanks for the comments all. Nehmo - your post alluded to a method I had considered, but im not skilled enough to know exactly what to do What you say makes sense, but I think ill either go with a breaker, or the method I talked abut. Thanks all for comments. Well, as long as I have your attention, it makes absolutely no difference whatsoever which outlet on a main line has a GFCI - each one only protects itself and what's plugged into it, and couldn't care less what's happening downstream: [view in fixed font, with wrap off] . . Mains Hot -------+-------------+-------------+ . Mains Neut. -----|--+----------|--+----------|--+ . | | | | | | . ------ ------ ------ . | GFCI | | GFCI | | GFCI | . ------ ------ ------ . P.C P.C P.C Where "P.C" means "Protected Circuit". What has been suggested, (sorry, don't remember by whom - jalegris?) is to use a GFCI circuit breaker, which goes on the left: . . ------- . Mains Hot --| GFCI |----+-------------+-------------+ . Mains Neut.--| C.B. |----|--+----------|--+----------|--+ . ------- | | | | | | . Ordinary Ordinary Ordinary . Outlet Outlet Outlet That's "on the left" in my attempt at a diagram - in real life, it goes in the breaker panel. Or, of course, you could upgrade your wiring - it will increase the resale value of the house considerably! :-) Good Luck! Rich Hi Rich, One of the 'recent' innovations is to build the GFCI circuit breaker into the 'first' outlet in the chain. On that outlet, the two sets of connections are isolated from each other, so that all downstream outlets are then protected. This allows you test and reset the circuit from inside, without having to go find the breakerbox. It has become standard in the NEC to do it that way now. But, the only way to really tell which outlet is first is to pull each one out, and buzz out each side. Takes a while, but is the only sure way to find out. Unless, of course, you took pictures of the wiring before they put up the sheetrock! Charlie |
#28
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Detecting first recepticle on a circuit
On 12 Feb 2006 11:55:55 -0800, wrote:
Great idea guys re GFCI right at the panel.. I think I might have to go this route anyway. Ive done about half the recepticles - Im confused because each recepticle is at the end of the line - ie wire comes in, but not out. Becasue of this im guessing that there is a central junction box (es) in the attic or ceiling with drops down to each recepticle. As an fyi - there are hardwired ceiling lights on the circuit as well, although none of the recepticles are switched (they are always live). Mine are like that. In most cases, wires to each receptacle and switch come from a junction box at the ceiling light fixture. The whole thing would look something like a giant octopus on top of the room with tentacles hanging down all over. In that case, maybe you could put a GFCI in a box next to the existing ceiling one. The other rooms use pigtails so each receptacle has it's own connection (no others depend on it). Many people have suggested getting in the attic. I'm going to try this, but its not going to be that easy. My house is a 1.5 story and the attic is very small - only a couple feet in the best of places, with lots of fiberglass - so mucking around in there will not be pleasent. My attic looks like that. Couple questions: 1) If I do as suggested and put the GFCI by the panel - will each recepticle be covered if its like I describe above? I can visualize quite easily a series of recepticles with the first being a GFCI and how they would all be covered. However in my case it seems a bit more complicated - ie lights, a junction box spreading to each recepticle, etc. Would this till be ok? Is there any situation where putting a GFCI as the first recpeticle on a circuit would NOT protect ones downstream? Something that won't work on shared neutral circuits. 2) Once Ive hooked up the GFCI, is there any way to CONFIRM each recepticle is covered? Ie something i can safely do to try and trip the GFCI (and something safe incase its not on the same circuit as the GFCI). Hopefully what ive said here makes sense. Ground each hot connection, through a resistor (just like the test buttons do). The resistor limits current in case the GFCI doesn't work. Thanks for the responses all, very helfull. -- Mark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin |
#29
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Detecting first recepticle on a circuit
On 12 Feb 2006 18:51:49 -0800, "Mikepier"
wrote: . You also want to make sure that you do _not_ have a ground connection between any of the downstream outlets. It's possible that the ground is hidden or that BX cable was used. I thought GFI's operation had nothing to do with the ground. It trips when it detects a current imbalance between the hot and neutral, regardless if theres a ground or not. I could be wrong though. A GFCI doesn't use ground. It responds to unintended ground connections (indicated by a difference brethren hot and neutral currents), like when you touch a defective power tool and become part of the circuit. The problem with connecting grounds (when no connection to earth exists) is not specific to GFCIs. If you have 2 receptacles connected this way, and an appliance plugged into one has a short from hot to ground (one that's not quite enough to trip the breaker), the ground connection at the other receptacle is now hot. You can get electrocuted by touching what was supposed to be a safety ground. -- Mark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin |
#30
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Detecting first recepticle on a circuit
On Sun, 12 Feb 2006 20:08:39 GMT, Fred Bloggs
wrote: canadian_woodworker Is there a simple way to figure out which is the first recepticle on a circuit? I have an older house - the two upstairs rooms are on the same circuit and are not grouned. Id like to add a GFCI plug on the first recepticle on that circuit, so every recepticle downstream is protected. Dudnt work that way- it is qwite posble there is no furst recept-icle. Put in a brak-er. That's when they're ALL first receptacles. Seems to be a common situation here. -- Mark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin |
#31
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Detecting first recepticle on a circuit
On 12 Feb 2006 08:29:17 -0800, "Sev" wrote:
I'm pretty unsophisticated- barely use meters- here's what I'd do. First, just try to trace the likely wire route by seeing where circuit exits panel, get up in attic and see if I can see where run drops down etc. Taking guess from this which is first receptacle in circuit- after turning off power- and testing to make sure it's off!- pull out this recep and disconnect black wires, then reconnect this recep, but not run which continues to rest of circuit- cap loose wire. Turn power back on and test to see if this recep is live, but rest of circuit dead. Of course if it is dead you probably reconnected run to rest of circuit and capped line from panel. This could be laborious if your guesses are wrong/ if it is difficult to trace wire route. Usually it is not that hard, but that does depend on how your house is wired/ whether attic has decking etc. It is easier if you begin by testing to see exactly which receps are on that circuit- turn it off and test them all to see which live/dead. And write down your test results, to avoid forgetting and redundant retesting. You could also mention what to do if you see only one pair of wires to the receptacle, maybe even short wires going to a soldered junction. -- Mark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin |
#32
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Detecting first recepticle on a circuit
According to Nehmo :
Chris Lewis - I think that most people would find that GFCI's don't false trip very often. If at all. I've never had one of mine trip when it wasn't clear it _probably_ had a good reason. False trips are suggestive of electrical boxes getting damp, bad extension cords, or oddities in old wiring (intermittent neutral-ground shorts) etc. Nehmo - GFCI nuisance trips are common. There are many ways that nuisance trips can occur, but they are by no means _commonly_ occuring. This article, Think Like a GFCI http://www.ecmweb.com/mag/electric_think_gfci/ discusses some causes: harmless leaks, capacitive leaks, cumulative (the fed outlets added together), and fluorescent fixtures may generate switching transients. The article deosn't say anything about how common these actually occur, and you're misinterpreting how "harmless" some of these things are. There's no such thing as a harmless leak. Even a neutral-ground intermittent is potentially a serious problem if it causes the grounding circuit to corrode. It's not supposed to carry current _unless_ there's a fault. Continuous current, especially in the presence of moisture, can easily cause grounding connections to eventually fail. So that tiny little leak can cause a full grounding failure later on that kills you. The GFCI is trying to tell you something. If you follow the guidelines of where to use GFCIs, nuisance trips are virtually non-existant. I've never seen one. And I've installed quite a few. Cumulative leaks is not likely to be an issue. Leakage in properly installed and dry systems is _extremely_ low. Vastly lower than the milliamps needed to trigger a GFCI. Not enough, even when multiplied by 10 or 15 to be an issue. And if it was, you still have issues with ground circuit corrosion. The other point I was trying to make is that by multiplying the GFCIs by a factor of 10, you're multiplying the possibility of GFCI burnout (by line-side spikes etc) by a factor of 10. Which in the long run outweighs the issue of nuisance trips. From a reliability standpoint, it's better to have fewer than more of these things. -- Chris Lewis, Una confibula non set est It's not just anyone who gets a Starship Cruiser class named after them. |
#33
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Detecting first recepticle on a circuit
Well, as long as I have your attention, it makes absolutely no difference whatsoever which outlet on a main line has a GFCI - each one only protects itself and what's plugged into it, and couldn't care less what's happening downstream: you can get outlets that proviide proteted output terminamls on the back to connect protect to other downstream standard outlets . Mains Hot ------+ +----------+-------------+ . Mains Neut. ----|-+ | +--------|--+----------|--+ . | | | | | | | | . ------ Ordinary Ordinary . | GFCI | Outlet Outlet . ------ . P.C note: ground connection present but not shown -- Bye. Jasen |
#34
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Detecting first recepticle on a circuit
jalegris
GFCI's on every outlet, but it's overkill. Or should I say underkill? You will note the confusion people in this newsgroup have about GFCIs. And this confusion is not limited to those people. Experienced electricians often don't even know what's inside of a GFCI. And everyday-people, people who typically use receptacles, sometimes are completely bewildered by them and how they should be used. When ordinary Smo discovers a downstream receptacle to be dead, sometimes that's the end of the troubleshooting. Smo simply concludes there is something wrong with the electricity, and he or she leaves it to somebody else to make the repair. However, if the receptacle Smo is using has a reset button on it, Smo, seeing the button right there, may try it, and he or she may succeed in repairing the electric problem. So a multiple-GFCI installation has a troubleshooting advantage. This equates to an installation that is up and working a higher proportion of its life. Thus, the multiple installation is superior. However, it costs more. In new construction, the labor cost of installing a GFCI receptacle is equivalent to that for a regular receptacle. The cost difference in materials isn't substantial. Consequently, new construction (on all but the cheapest of projects) should have a GFCI at every receptacle where GFCI protection is needed. In retrofits, each replaced receptacle is an added cost. And in some older houses, the old small boxes won't accommodate a GFCI. So an inexpensive way to protect all the outlets on a circuit is to just use the GFCI on the first outlet. -- (||) Nehmo (||) |
#35
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Detecting first recepticle on a circuit
In Canada, GFCI outlets have input and output terminals so you can
protect a whole chain of downstream outlets with just one GFCI. You could put a GFCI on every outlet, but that's overkill. Or should I say underkill? -- Joe Legris |
#36
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Detecting first recepticle on a circuit
Rich Grise wrote:
Well, as long as I have your attention, it makes absolutely no difference whatsoever which outlet on a main line has a GFCI - each one only protects itself and what's plugged into it, and couldn't care less what's happening downstream: [view in fixed font, with wrap off] . . Mains Hot -------+-------------+-------------+ . Mains Neut. -----|--+----------|--+----------|--+ . | | | | | | . ------ ------ ------ . | GFCI | | GFCI | | GFCI | . ------ ------ ------ . P.C P.C P.C Where "P.C" means "Protected Circuit". Right - when wired as drawn above. But GFCI receptacles can be wired to protect downstream receptacles/wiring as well. They are marked with a line and load side. The wiring on the line side of the GFCI receptacle is not protected by the GFCI. The GFCI contained receptacle, and everything on the load side is: --------- -------- Mains Hot -------| GFCI |------| Regular|--- etc Mains Neut. -----| Recpt. |------| Recpt. |--- --------- -------- Line Load What has been suggested, (sorry, don't remember by whom - jalegris?) is to use a GFCI circuit breaker, which goes on the left: . Cheaper to install a GFCI receptacle in the first position on the branch, and equally effective for ground fault protection as a GFI circuit breaker. But you can't do that on a multiwired branch with a shared neutral. For such a branch circuit, you wire only to the line side, and the GFCI receptacle feeds nothing down stream. Or you could feed a non-shared neutral circuit downstream through the GFCI receptacle, which implies adding an extension to the existing multiwire. Ed |
#37
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Detecting first recepticle on a circuit
On 13 Feb 2006 17:15:50 -0800, wrote:
In Canada, GFCI outlets have input and output terminals so you can protect a whole chain of downstream outlets with just one GFCI. You could put a GFCI on every outlet, but that's overkill. Or should I say underkill? Is that different from the LINE and LOAD terminals? -- Mark Lloyd http://notstupid.laughingsquid.com "Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well armed lamb contesting the vote." - Benjamin Franklin |
#38
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Detecting first recepticle on a circuit
On Mon, 13 Feb 2006 16:01:47 -0800, Nehmo wrote:
In retrofits, each replaced receptacle is an added cost. And in some older houses, the old small boxes won't accommodate a GFCI. So an inexpensive way to protect all the outlets on a circuit is to just use the GFCI on the first outlet. It seems I've learned something today. It sounds like you're describing an outlet and circuit breaker in one box. So, when any outlet on the "output side" trips it, the whole string goes out? Does the first one still work? I.e., does it have two reset buttons? Thanks, Rich |
#39
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Detecting first recepticle on a circuit
Rich Grise wrote:
On Mon, 13 Feb 2006 16:01:47 -0800, Nehmo wrote: In retrofits, each replaced receptacle is an added cost. And in some older houses, the old small boxes won't accommodate a GFCI. So an inexpensive way to protect all the outlets on a circuit is to just use the GFCI on the first outlet. It seems I've learned something today. It sounds like you're describing an outlet and circuit breaker in one box. So, when any outlet on the "output side" trips it, the whole string goes out? Does the first one still work? I.e., does it have two reset buttons? Thanks, Rich Not in any I've seen. The outlet with the protection circuit trips out, disconnecting its own load and allt he downstream ones. Cheers. Ken |
#40
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Detecting first recepticle on a circuit
On Tue, 14 Feb 2006 22:00:09 GMT, Rich Grise
wrote: On Mon, 13 Feb 2006 16:01:47 -0800, Nehmo wrote: In retrofits, each replaced receptacle is an added cost. And in some older houses, the old small boxes won't accommodate a GFCI. So an inexpensive way to protect all the outlets on a circuit is to just use the GFCI on the first outlet. It seems I've learned something today. It sounds like you're describing an outlet and circuit breaker in one box. Not quite - it just has a GFCI trip, no overcurrent trip, so it does not replace a normal circuit breaker. So, when any outlet on the "output side" trips it, the whole string goes out? Does the first one still work? I.e., does it have two reset buttons? The GFCI outlet, and any outlets connected to its "load" terminals, will switch off on a fault (or test). There is a single reset button to restore power to the GFCI outlet and any downstream outlets. Thanks, Rich -- Peter Bennett VE7CEI email: peterbb4 (at) interchange.ubc.ca GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html Newsgroup new user info: http://vancouver-webpages.com/nnq |
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