# Burned / Melted GFI



## adgjqetuo (Oct 21, 2011)

First off some background information. We bought this house 6 months ago as a short sale property. The house was built in 2000 but the org. owners didn't take well care of the house by any means. 

So I was starting to paint and I began taking off the outlet covers. I came to the one GFI in my kitchen and found what didn't look right. I turned off the circuit and unscrewed the GFI from the box. I couldn't believe what I found! The GFI was completly melted and the wire attached was burnt to a crisp. I cut the damaged wire out. I looked at the GFI and realized I have two 20 amp breakers in the basement but the GFI had 15 amp on the side. Long story short I found out from further inspection that the builder put ALL 15 amp plugs including the other GFI in the Kitchen. I would assume the old owners plugged in something that drew more then 15 amps which melted the plug but less then 20 so the breaker didn't trip.

I replace all 10 plugs and 2 GFIs in my kitchen with the correct 20 amp version. I got thinking though, is it possible the wire could have burned through somewhere else (not just at the plug) but behind the walls somewhere hidden waitting to be a fire hazard? I'm not sure how I would ever go about that though. The wire could be ran anywhere.










Thanks for the help,
Mike


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## a_lost_shadow (Dec 18, 2011)

You're actually allowed to put 15 amp plugs on a twenty amp circuit. I don't think it's likely that the problem was due to 20 amps being put on the circuit. Remember that for 20 amp circuits, you need to use 12 gauge wire regardless of whether you use 15 amp receptacles. Thus your wire should be able to handle 20 amps perfectly fine. Additionally, if the damage was from overloading the wire, I'd expect to see damage on both the neutral and hot wires. Since both wires would be seeing the same current under load.

What's more likely is that back stab connection between the hot wire and the GFI was loose. I've heard that back stabs don't make the best of connections, and personally think they're more pain then they're worth. So probably that connection was arcing on and off whenever someone put load on the outlet. Eventually the plasma from the arc built up enough to cause a small fire and the damage you see there.

Hmm, another thought just hit me. Nowadays back stabs can only handle 14 gauge wire, not 12 gauge. Did you confirm that the builders actually pulled 12 gauge? I don't know how long that rule has been in effect. So it's just being overly cautious to check. But if you haven't checked, you might want to.

Finally, if you're really worried about the wire, I'd suggest using a multi-meter to measure its resistance between the hot and neutral, as well as compare the resistance on the lines to those of another circuit.


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## ArkanSparky (Feb 2, 2012)

The back stabs on GFI's are made for 12 or 14 gauge most of them you can't wrap around the screw terminals, chances are the screws weren't tight enough and yes you can put 15 amp receps on 20 amp breakers.


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## ArkanSparky (Feb 2, 2012)

Maybe that helps


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## adgjqetuo (Oct 21, 2011)

Dumb question, but how do I check if its 12 gauge?

I don't remember it feeling thicker then the rest of the house when I replacd some other 15 amp plugs the old owner painted on top of.

If it is 14 gauge on the 20s, what does this mean? Fire hazard? What would you suggest?

My wife and I don't use the plugs for anything current heavy hardly ever. At most a blender, toaster oven, or small stand up mixer but on seperate plugs and then disconnected after use. And never at the same time.


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## kbsparky (Sep 11, 2008)

GFI's do not use "back-stabs"

They are_ back-wired_, which is very different from _back-stabbing_.

The wire is stripped, and inserted into the holes in the back of the device, and then the screws on the side are tightened/torqued for a good electrical connection.

The problem shown in this thread is one of those terminals had a loose connection, resulting in a burn-out from a heavy load on the circuit. The loose connection could have been from a loose terminal screw, or an internal connection within the device itself. Either way, the result is the same.


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## AllanJ (Nov 24, 2007)

I hope you labeled the wires back in the wall as to which wire went where on the GFCI unit (line; load). Top right, center left, etc. are not good labels becuase the positions differ on differnt brands of GFCI's, switches, etc.


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## curiousB (Jan 16, 2012)

ArkanSparky said:


> The back stabs on GFI's are made for 12 or 14 gauge most of them you can't wrap around the screw terminals, chances are the screws weren't tight enough and yes you can put 15 amp receps on 20 amp breakers.


In IL backstab connections are banned. You must use screw connections for wiring. Maybe examples like this are why.


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## zappa (Nov 25, 2011)

curiousB said:


> In IL backstab connections are banned. You must use screw connections for wiring. Maybe examples like this are why.


Check out kbsparky's post for a better explanation. The receptacle in the picture is not a backstab.


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## adgjqetuo (Oct 21, 2011)

AllanJ said:


> I hope you labeled the wires back in the wall as to which wire went where on the GFCI unit (line; load). Top right, center left, etc. are not good labels becuase the positions differ on differnt brands of GFCI's, switches, etc.


Yeah, I made sure to allign the line and load wires appropriately when adding the new GFI. But if the builder used 14 gauge instead of 12 is that a big problem? How can I tell?


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## gregzoll (Dec 25, 2006)

curiousB said:


> In IL backstab connections are banned. You must use screw connections for wiring. Maybe examples like this are why.


No they are not illegal in Illinois. It is just that there are some inspectors that frown against them, due to they know that they fail over time. Again, GFI's, commercial grade outlets that use a screw to hold down the wire, when inserted into the back hole, are not "back-stab's".


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## gregzoll (Dec 25, 2006)

adgjqetuo said:


> Yeah, I made sure to allign the line and load wires appropriately when adding the new GFI. But if the builder used 14 gauge instead of 12 is that a big problem? How can I tell?


You can tell by the "weight" of the wire. That is, if it is easier to bend by fingers, it could be #14. Other way is to try to get to the outer jacket of the wire and look. That age of a home, it would be #12 for the Kitchen/SABC, along with Bath, and most likely all other outlets.


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## JACK HOTTEL (Dec 15, 2011)

You can disconnect a wire and measure it, if you have a caliper. # 14 is 0.0641" in diameter. # 12 is 0.0808". Small pocket wire gauges are also available. Probably the simplest way is to obtain a small sample of each size and compare them to the existing wiring. The difference in size is readily apparent. Only the actual conductor is measured, not the insulation.
If the wiring is #14 you will need to change the breakers on those circuits to 15 amperes.
Jack Hottel


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## zappa (Nov 25, 2011)

gregzoll said:


> You can tell by the "weight" of the wire. That is, if it is easier to bend by fingers, it could be #14. Other way is to try to get to the outer jacket of the wire and look. That age of a home, it would be #12 for the Kitchen/SABC, along with Bath, and most likely all other outlets.


It has always amazed me at how much more difficult it is to work with #12 vs. #14


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## Stubbie (Jan 7, 2007)

kbsparky said:


> GFI's do not use "back-stabs"
> 
> They are_ back-wired_, which is very different from _back-stabbing_.
> 
> ...


As Kbsparky has pointed out the connections are very different, 'back wire' is good especially with stranded wire but it does need to be carefully connected. By this I mean proper stripping to keep the insulation from being pushed under the clamping plate. You must also push the side screw inwards to open up the connection hole so that you do not get the wire behind the plate. Here is what they look like and it will show how the connections differ .......


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## adgjqetuo (Oct 21, 2011)

Thanks for the clarification - it does appear to be 14, but I don't see any markings. It doesn't seem any thicker then a plug in my living room which is on a 15 amp breaker.

Knowing this, is this a problem? Am I against code for putting in the 20 amp plugs instead of keeping them at 15 like the builder had? The breakers are 20, but you guys said that was OK, so I just wanted to clarify.


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## a_lost_shadow (Dec 18, 2011)

My poor man's way of checking wire gauge is just to use my multi-gauge strippers. 14 gauge will go cleanly through both the 14 & 12 gauge holes, while the stripper will actually catch 12 gauge in the 14 gauge hole. Granted this does require the strippers to be in decent shape. Also if you use this method, be careful that you don't apply too much force to the strippers. You don't want to nick a 12 gauge wire when you test it in the 14 hole.

If you have anywhere you can see the wire's sheathing, such as in the attic, you can just look at the identifier on the wire. I believe the manufacturer is required to mark the wire every few feet. If you have wire with raised lettering, rubbing over the outer covering with a dirty finger can make it more legible.


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## a_lost_shadow (Dec 18, 2011)

Ah, didn't see the last post. If you do have 14 gauge wire then you are required to use 15 A receptacles and breakers (unless you pull new 12 gauge wire). Using 20 A receptacles and breakers is a fire hazard.


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## adgjqetuo (Oct 21, 2011)

Thanks for the reply, I just find it really hard to believe the builder put in 20 amp breakers with 15 amp receptacles on (what appears) 14 gauge wire... something doesn't seem to add up. Its not like the house is that old.

Like I said earlier, I replaced all the 15 amp plugs that were on the 20 amp circuit with 20 amp plugs. I hope I didn't do more harm then good...

I also noticed all 3 bathrooms are on a single 20 amp circuit sharing one 15A GFI in one of the bathrooms, the other two having 15A regular receptacles.

I will try your wire stripper idea tomorrow.


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## jbfan (Jul 1, 2004)

adgjqetuo said:


> Thanks for the reply, I just find it really hard to believe the builder put in 20 amp breakers with 15 amp receptacles on (what appears) 14 gauge wire... something doesn't seem to add up. Its not like the house is that old.
> 
> Like I said earlier, I replaced all the 15 amp plugs that were on the 20 amp circuit with 20 amp plugs. I hope I didn't do more harm then good...
> 
> ...


Not the best idea, but code compliant.


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## adgjqetuo (Oct 21, 2011)

So just to clarify, the bathrooms are code compliant, but if I swapped the plugs in all 3 bathrooms from 15 to 20 (including the GFI) I'm no longer in code? Even though the breaker is 20?

Sorry for any redundent questions, just trying to understand.


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## Stubbie (Jan 7, 2007)

adgjqetuo said:


> So just to clarify, the bathrooms are code compliant, but if I swapped the plugs in all 3 bathrooms from 15 to 20 (including the GFI) I'm no longer in code? Even though the breaker is 20?
> 
> Sorry for any redundent questions, just trying to understand.


I'd stop thinking about changing receptacles to 20 amp rated. What you really need to do is verify your wire size on the receptacle branch circuits and the bathrooms. You might get lucky and they may have used color jackets on the romex cable. If the outer jacket is yellow then you have 12 awg copper. Other wise stop guessing and find somewhere you can verify the wire size. Your going to cause yourself unnecessary cost.
I'm betting if the house was built in 2000 your going to find out you have 12 gauge connected to those 20 amp breakers.


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## curiousB (Jan 16, 2012)

gregzoll said:


> No they are not illegal in Illinois. .....".


 

Section 110-14 Electrical Connections, is hereby amended by adding the following thereto at the end of the first paragraph of said section:

All branch circuit conductors shall be connected to receptacles, switches and other such devices by means of screw terminals that are manufactured as part of the device. All branch circuit conductors shall be spliced or looped in such a manner as to provide for no more than one conductor to be connected to an electrical device screw terminal. *The insertion of any conductor into a screwless terminal of any electrical device shall not be approved.

*


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## gregzoll (Dec 25, 2006)

curiousB said:


> Section 110-14 Electrical Connections, is hereby amended by adding the following thereto at the end of the first paragraph of said section:
> 
> All branch circuit conductors shall be connected to receptacles, switches and other such devices by means of screw terminals that are manufactured as part of the device. All branch circuit conductors shall be spliced or looped in such a manner as to provide for no more than one conductor to be connected to an electrical device screw terminal. *The insertion of any conductor into a screwless terminal of any electrical device shall not be approved.
> 
> *


Means nothing to me in my part of the state. Again, they are not illegal where I live, and only if a inspector does not like the connection, will they make the person doing the job change it to a different connection. Let me guess, you live up in that mob/union part of the state called the Socialist Society of Chicago/Crook County.


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