Catastrophic GFI failure, need information

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Old 06-03-09, 04:07 PM
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Catastrophic GFI failure, need information

I installed a new Cooper brand 20 amp GFI in my neighbors home about two years ago. The unit functioned flawlessly until yesterday, the unit burst into flames!!

There is a black streak up his brick wall, the steel electrical box and wires are black, and 1/3 of the GFI is literally melted into a glob! Fortunately this was a retrofit and was in a steel box, had it been plastic it may have been a sad story.

I can see no evidence of installation failure, all wires are still tight, the hot terminal melted right out of the unit, and there was no wire to wire short. What is most disturbing is that the 20 amp breaker never tripped!

The GFI was mounted in a metal box on a 20 amp circuit, the box has a seal that shows no sign of water infiltration, the box is covered by a sealed aluminum lid, and the receptical was used for a swimming pool pump rated at a maximum of 12 amps. The unit was heard arcing and a smell of smoke was detected in the home.

Anyone ever see this happen before or have any idea what may have happened?
 
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Old 06-03-09, 05:48 PM
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What size wiring was used in the metal box? How close to the metal box was the GFCI? Remember the GFCI only protects the appliance plugged into it and downstream. It has nothing to do with the incoming wiring, as it is still line voltage and must rely on the breaker. Was the metal box properly grounded? Did the pool pump malfunction and cause a spike in amperage?
 
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Old 06-03-09, 05:57 PM
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The input wire is #12 solid, the pool filter is now running after I replaced everything, the 20 amp GFI barely fit into this box but the design makes it impossible to touch the sides, there were no arc marks in the box. I even wrapped tape around the GFI when I installed it to make it further unlikely to ever short anything. The ground wire was connected to the box and the GFI. The filter motor is a piece of SO cable home runed right to the motor. The damage was as if the inside of the unit just went into melt down.
 
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Old 06-03-09, 08:35 PM
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It was not an over current problem. That is why the breaker did not trip. I would bet that since the #12's connecting to the device were still tight that there was a poor connection between the cord cap on the pump cord and the GFCI itself.
 
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Old 06-03-09, 09:42 PM
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I agree the plug was probably loose in the receptacle and caused the arc. Maybe somebody or a pet tripped over the cord and knocked it loose?
 
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Old 06-03-09, 10:30 PM
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Might want to consider a twist lock receptacle and cord cap. Might have to use a double gang box and a blank face GFCI plus receptacle. or do they make a twist lock GFCI?
 
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Old 06-03-09, 10:36 PM
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I had an outlet splitter (one piece unit plugs into one of the duplex and gives you 4 outlets (plus surge etc)) do that a little while back. The contact plates for the plug spades were arc'd and burnt pretty bad. Luckily, as the unit heated up and melted it managed to trip its own breaker. The panel breaker didnt trip (15a.. FPE mind you.. lol)

Im guessing its the China effect. Is melted outlets (or GFI outlets) not something fairly new ? Are they using cheaper metals or a less failsafe design for the connection tabs ?
 
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Old 06-03-09, 10:38 PM
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Originally Posted by ray2047 View Post
Might want to consider a twist lock receptacle and cord cap. Might have to use a double gang box and a blank face GFCI plus receptacle. or do they make a twist lock GFCI?
Should a pool circuit not be a unique circuit with its own breaker ? A GFI breaker might work nice.
 
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Old 06-04-09, 02:00 AM
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Originally Posted by DaveC72 View Post
Should a pool circuit not be a unique circuit with its own breaker ? A GFI breaker might work nice.
Dave.,

It may work with GFCI breaker however the OP did not stated which type of pool he have there so there are few unanswered question that the OP have to answer it first.

There are few parts of NEC code is not the same as your CEC code is espcally with swimming pool set up.

The only way to get the GFCI recpetale to burn up like that is if cord is loose or the recptale itself is allready loose over the time.

Now for the steel box you mention have hard time to get in there., what size box you have in there if you used the " handi box " there is no way you can able get the GFCI recpectale in there without getting any conductor shorted out.

If you have deep well single gang metal box then discharge my last sentince above.

Ray.,

There is no twistlock GFCI recpectale on market however there is one way you can get this to meet the code is get a faceless GFCI and take the load side of GFCI faceless device to the twistlock { this will need two gang box }

Now once you fix up the issue you should deal with the cord get some kind of stain relif gizmo so it will not put any strain on the plug itself.

Merci,Marc
 
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Old 06-04-09, 05:37 AM
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The box is a deep handy box and as I said, not much room. The GFI is made instead of just a block, it has indentations causing the terminals to be sunk back in the unit. IMO, there is no way that it touched the side and I looked for arc marks and found none. If it had arced, being that the box is grounded, the breakers should have tripped. It was mentioned by my neighbor "would it matter if I didn't push it all the way in" which to me meant just a little, not hanging 1/2 way out. I will ask that question and see what he conciders not pushed in.

I agree with the GFI Breaker idea, the problem is that these houses are GE Pushmatics, I don't think that they make a GFI for that.
 
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Old 06-04-09, 03:09 PM
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You are opening another can of worms, now. GE pushmatics? Sight unseen, they probably had a bad breaker that refused to trip.
 
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Old 06-04-09, 03:26 PM
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Originally Posted by HotRod53F100 View Post
GE Pushmatics
GE? As far as I know pushmatics were only made by Bulldog/ITE. There is an aftermarket GFI replacement breaker, but you really don't want to see the price tag if you can find a dealer anymore.
 
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Old 06-04-09, 03:44 PM
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You may be correct about ITE, going by memory I was thinking GE. I'll have to look, I have them in my home too.
 
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Old 06-04-09, 06:22 PM
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Hotrod .,

Once you know what brand name the panel box it is and the type of breaker it will really help us alot to find the correct item you are looking for.

Merci,Marc
 
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Old 06-04-09, 06:25 PM
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I was thrown by the GE, concentrating on the word "pushmatic", but I think you are correct that they were ITE.
 
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Old 06-04-09, 09:10 PM
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Being a pool, and yes our codes probably differ.. Id still like to be using a GFI breaker.

But, if this was due to an arcing problem, as in loose connection point.. then isnt what is wanted.. an 'arc-fault' breaker ?

Im not sure if these trip on chattering overcurrent only (where the persistence of current isnt high enough to trip a reg breaker), or *any* chattering current (like a partial open in a loose connection point).

Maybe a combination AFI/GFI breaker is too much to ask ?
 
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Old 06-05-09, 09:10 AM
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Originally Posted by DaveC72 View Post
Being a pool, and yes our codes probably differ.. Id still like to be using a GFI breaker.
There's nothing wrong with a GFCI receptacle for a plug-in pool pump.

Maybe a combination AFI/GFI breaker is too much to ask ?
They do exist, but you have to be careful about what combo actually means.

There are two levels of GFCI protection, personnel (5mA) and equipment (30mA). Pools (kitchens, baths, etc) must have a GFCI with personnel protection, which is sometimes also called Class A.

There are also two levels of AFCI protection: series and parallel which trip on arcs which are either in series with the load (your kind) or parallel with the load and correspond to roughly 5A and 70A faults on a 20A circuit if I remember correctly.

All of the manufacturers do make combination AFCI/GFCI breakers, however you need to read the cut sheets very closely to see which technologies are combined to ensure that the pool has personnel (5mA) protection. Most AFCI/GFCI devices only provide GFCI at the equipment (30mA) level. Also the phrase "Combination AFCI" in the marketing literature usually means an AFCI breaker which can detect both series and parallel arcs, but may not have significant GFCI protection. On top of all that, some of the manufacturers claim to have series arc detection, when in fact if you read the fine print it will say something like "after series arc progresses to parallel or ground arc". This essentially means they don't detect series arcs, but just wait for enough stuff to melt until there's a parallel arc the breaker can detect.
 
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