I replaced a receptacle for someone last night. It was a GFCI. The face place was completely charred, the buttons were completely melted and fused into a molten mess. The outlet into which a heater was plugged had one of the prong slots completely melted and the other prong slot was pretty much on its way to being melted. The other outlet at the top of the duplex, while charred somewhat was for the most part ok, recognizable, and looked like it would’ve still been usable. Upon removal of the GFCI the back of the unit looked brand new, no signs of damage at all, or on the sides of the unit. Only the front had this damage. The plug of the heater that was plugged into it was nonexistent, it had just melted in the “fire” and unusable.
Obviously there was something wrong the heater that caused the fire. But the GFI never tripped. The wire was 12ga feeding the receptacle and was in excellent shape.
Should a GFI tripped in this case?
Replies
No, it wont trip in that case. I think the GFI may have had an electronic failure.
This sounds like a bad connection between plug and socket. This will generate heat! With a heater pluged in you are running near the suggested max of that socket. I suggest you replace the heater plug too.
it would seem that the heater finally scorched the GFI.
space heaters are a constant "forgotten" load...with large wattages, up to 1800 watts or more, and will overheat tinsel cord extensions and their cheap molded plugs .. large looking extension cords eventually have problems as well
even the plugs on the heaters have been damaged...
space heaters under desks in cubicles are a source of regular complaints in offices at this time of year, with units being left on over the weekends especially....
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Edited 11/18/2006 10:28 am by maddog3
Sooo right!
To the OP.
GFCI recepticals trip on GROUND FAULTS, not circuit overloads or a dead short of hot to neutral.
maddog3 gave you the most likely scenerio for the burn out.
Our local AHJ issued an advisory in September recomending that electrician run dedicated circuits and AFCI breakers for retro work where space heaters will used.
A lot of house fires get started from electric space heater usage.
Dave
I have been reading where the mfrs.of the arc fault stuff, mainly SqD , are pushing the NEC for a WHOLE HOUSE requirement for ' 08gotta sell those things somehow I guess.
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I have a copy of the proposed 08 and it does have a requirement COMBINATION type AFCI protection on all 120v 15 & 20 amp branch circuits in dwellings.Don't have any idea of the status of those proposal are.And I dont' know what a COMIBNATION AFCI is.The standards have defined several types. One of which adds serial arc detection. Another type is gives AFCI type of protection at the receptacle.As far as I know none of those other types are available yet.
Sq D started the whole AFCI craze IIRC, but no one seems to be able to manufacture a unit that does what was promised when this all started....I don't know what a "combination afci "....is either.it should significantly add to the cost of a new service however.
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A number of localation have opted out of the AFCI requirement or modified them to only require it on bedroom receptacles.But I don't have any idea of what percentage homes that is.Also from some searching it seems that many CA cities (so it might be statewide) DOES NOT require AFCI's when doing a service/panel upgrade.
Would a combination unit be both AFCI and GFCI? I would imagine that would be VERY expensive. ALso, if ordinary AFCI breakers were required for the whole house in a panel upgrade, think of the number of GFCI breaker protected circuits that would have to be traced and rewired with GFCI recepticles.
I don't think that it a combination of AFCI and GFCI although I think that I have heard that someone makes such a device or has introduced one.
this is the UL definition of a "combination " AFCI......
I found it about five minutes agoArc Fault Circuit Interrupters, Combination Type - An AFCI which complies with the requirements for both branch/feeder and outlet circuit AFCIs. It is intended to protect downstream branch circuit wiring and cord sets and power-supply cords.hope this cleared it up for ya....I'm still scratching my bean.
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http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=81702.1
Edited 11/19/2006 10:06 am by BillHartmann
OMG.....!no,no, not that one.
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I see that I had the correct like. Just 3 copies in a row and that confused the system and it reverted to the first thread.http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=81702.1
I know Wis. had NOT adopted it ....again.... for the '05 Code....." Also from some searching it seems that many CA cities (so it might be statewide) DOES NOT require AFCI's when doing a service/panel upgrade." yep,it would be impossible to use them for an upgrade if there are existing multi-wire circs.....unless those are run in conduit !!the things are a real PITA.....IMO.
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Cutler Hammer does make a two pole AFCI that could be used on multi-wire curcuits. I think that I have heard that they are the only one, but not sure.But I don't see that as such a big stumbling block.While this might vary by region and by electrican I don't think that many circuits that feed bedrooms are multi-wire.But they could require the AFCI's and just except EXISTING multiwire circuits from that requirement.
I have figured out the AFCI and am starting a new thread.
I was not aware that "arc faults" were such a problem!! All this fancy stuff and we still can't get people to replace the batterys in the smoke dectector.
The vast majority of "electrical fires" start with a bad connection that overheats. In most cases of an overheated connection the result is just like this one -- eventually the connection gets hot enough to melt down the connectors involved, and then the connection is broken and damage is minimal. But in a few cases either the overheating directly starts a fire, or the wiring insulation melts and produces an electric arc of sorts that can really get things burning.But it all starts with the bad connection.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
Might it be that the outlet was rated for 15 amps and the circuit was rated for 20? Feed wires would have stayed cool enough while the internal contacts of the outlet would have started to heat up.Just a thought,Frankie
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Embarrass any tough roots from the samphire. Then bamboozle till it's al dente with that certain je ne sais quoi.
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You can easily overheat the contacts with only 5-10 amps, if the contact resistance is high enough.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
ALL 15 amp receptacles are rated for 20 amp feed through and can be used on 20 amp circuits. And GFCI's are also rated for 20 amp feedthrough to the load terminals.If you are on a 20 amp circuit you are suppose to be able to safely draw 20 amps at that receptacle. Such as 2 10 amp loads or a 15 and 5.And with one exception I have never seen anything with a 15 amp plug that will draw more than 15 amps.That exception being stationary power tools. Specially imported ones. Many of them have 1 1/2 hp motors with labeled full load currents of 15-18 amps.
The feed thru stuff I don't understand. In my posting that started this mess....the GFI was rated for 15A and a 20A feed thru. I"m not sure I understand what that means....does it mean the receptacle (GFI in this case) is rated for a load only up to 15A but that the feed thru (I assume this means a wire splice in the receptacle box to continue downstream elsewhere) can go to somethat that draws 20A?
Does it mean the breaker can be a 20A brkr even though the receptacle is rated for 15A? It doesn't make sense to me if that is the case because you can't put 14ga wire on a 20A brkr and it sounds the same to me as if that's what you're doing...sorta. What does the "feed thru" mean really? If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME
In a 15 amp receptacle the wipers (contacts) in the receptacle and in the plug are designed to handle a max of 15 amps.The common duplex receptacle consists of TWO receptacles. Each set of contacts is designed to handle a max of 15 amps.But the connections (screw terminals or clamps) and the buss bar connection in the receptacle is designed to handle a maximum of 20 amps.Thus it can be connected to a 20 amp circuit. All of the parts that might be carrying 20 amps is rated for 20 amps.That would include the wire (#12), the screw terminals (or back clamps such as used on the GFCI's), the relay contacts in the GFCI, the bus bar straps on the side of the duplex receptacle are all designed to handle 20 amps. The only thing is limited to 15 amps is the each individual receptacle contacts and the matching plug.Thus you can have any combination of loads that adds up to 20 amps.It can be two 10 amp loads in this receptacle or example or maybe a 5 amp load in this recptacle and a downstream (freed through) receptacle that has a 10 and a 5 amp load. Anything that is in series is rated for 20 amps.Thus a 20 amp circuit is allowed to use 15 amp receptacles as long as you have more than one receptacle (and the duplex counts as two) on the circuit.Or the same receptacles and GFCI can be wired with #14 and connected to a 15 amp breaker.(Note if the back stab terminals are used on residential grade receptacles they are limited to #14 wire adn thus 15 amp circuits. But if the screw terminals are used the same ones can be used with #12 on a 20 amp circuit. The back stab are those with a hole that you poke the wire in and it is help with a spring. That is different from the back wire on GFCI receptacles that has a plate that hold the wire when the terminal is screwed down.)
Thank you. AS for the backwired method, I'll NEVER do that. I've replaced a number of recepts where the backwiring caused some kind of issue. I always use the screw terminal or the pressure-plate screw connection.If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME
This is not unusual. Likely the connection between the heater plug and the GFI socket contacts was poor, resulting in heating which further compromised the connection. There is never an overload (in fact, current will go DOWN slightly as this occurs), and there is never a short to ground (at least not until the charring causes it), so a breaker or GFCI won't trip.
Alternatively, the heater plug could have developed a bad internal connection, with essentially the same result.
Presumably an arc-detecting breaker would have tripped.
don't think an AF breaker would trip either, unless there was a
L-N arc..
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Hard to say for sure. It's certainly more likely to trip than a regular breaker or a GFCI, both of which have essentially zero chance of tripping in this scenario.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
that's the beauty of 'em......they do one damn thing, besides, maybe the panel where this happened won't accept one.BTW, I just came home from Lowe's and both GE and Sq D are still within pennies of $35...is it any wonder they want these things to be used to fill up a panel.
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You say the face plate was melted? Maybe the heater was pointed at the wall.
The recept was up above the sink. The space heater on the floor. Don't think it's likely the heater melted the face.If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME