What the heck happened here

[Mr. Serious]

It's a common misconception, but 20a receptacles don't carry 20a any better than 15a receptacles do.

I may take apart some GFCI receptacles and verify this.

I started using the 20A ones for two reasons:
First, sometimes I'm installing them where it really should be a 20A receptacle by code, so I can carry only the 20A ones and I don't have to stock both types.
Second, several years ago I had the same thing happen to me multiple times: A 15A GFCI would trip with the load shorted, then when resetting the GFCI with the shorted load still connected, the GFCI would blow up and the 20A breaker would trip. We've already discussed this on the forum and everyone assured me that GFCI receptacles aren't even supposed to trip with an overcurrent condition, only with an imbalance.

So, I don't know, maybe the 20A ones really aren't any better.

 

[hillbilly1]

I may take apart some GFCI receptacles and verify this.

I started using the 20A ones for two reasons:
First, sometimes I'm installing them where it really should be a 20A receptacle by code, so I can carry only the 20A ones and I don't have to stock both types.
Second, several years ago I had the same thing happen to me multiple times: A 15A GFCI would trip with the load shorted, then when resetting the GFCI with the shorted load still connected, the GFCI would blow up and the 20A breaker would trip. We've already discussed this on the forum and everyone assured me that GFCI receptacles aren't even supposed to trip with an overcurrent condition, only with an imbalance.

So, I don't know, maybe the 20A ones really aren't any better.

If the load is shorted to ground, the gfi will trip.

 

[LarryFine]

We've already discussed this on the forum and everyone assured me that GFCI receptacles aren't even supposed to trip with an overcurrent condition, only with an imbalance.

A GFCI should trip if the over-current is due to contact with the EGC, earth, or other grounded surface.

If the over-current (or a shock) is due to a line-to-neutral (or to-line) contact, the GFCI should not trip.

 

[letgomywago]

I may take apart some GFCI receptacles and verify this.

I started using the 20A ones for two reasons:
First, sometimes I'm installing them where it really should be a 20A receptacle by code, so I can carry only the 20A ones and I don't have to stock both types.
Second, several years ago I had the same thing happen to me multiple times: A 15A GFCI would trip with the load shorted, then when resetting the GFCI with the shorted load still connected, the GFCI would blow up and the 20A breaker would trip. We've already discussed this on the forum and everyone assured me that GFCI receptacles aren't even supposed to trip with an overcurrent condition, only with an imbalance.

So, I don't know, maybe the 20A ones really aren't any better.

Only reason I've used them is when I've had actual 20a dedicated circuits like a sauna or something else like one

 

[Alwayslearningelec]

It looks melted. Could be a loose connection on the receptacle that caused the excess heat under load that melted the plastic. You would need to open it up to know for sure.

What do I look for ? I'm trying to determine for sure if he plugged something into this. He's denying it but this receptacle hasn't been used for a while and all of a sudden he gets a Tesla and has been asking for a charger( which I finally got.instslled.for him) and during this time the receptacle burns up right by his Tesla.

 

[Alwayslearningelec]

Would you say more than likely something bad to be plugged into the outlet for this to happen?

 

[retirede]

Would you say more than likely something bad to be plugged into the outlet for this to happen?

I don’t think that describes it correctly. A (heavy) load was plugged into that receptacle which that receptacle (in its current condition) could not adequately handle.
Why? We can’t tell from here. It could be poorly torqued connections, corroded contact points, a worn out receptacle that lost some contact force, a faulty plug on the load, or some combination.

 

[Alwayslearningelec]

Okay I get it but more than likely something had to have been plugged in correct

 

[kwired]

Even a hefty 120 volt plug in appliance should not cause the receptacle to melt if it was properly installed.

Yet it happens all the time with things like space heaters or other items that run fairly continuously at high load level.

Cheap and/or undersized extension cord plugged in to power such load sure won't help matters.

I have to laugh at some those space heaters marketing about how safe they are, no extreme temps at operating surfaces, vent openings, etc. and being impossible to start a fire. Yet I have seen same units cause melt down at the receptacle several times. Even occasionally when spec grade receptacle was used.

 

[Alwayslearningelec]

Yet it happens all the time with things like space heaters or other items that run fairly continuously at high load level.

Cheap and/or undersized extension cord plugged in to power such load sure won't help matters.

I have to laugh at some those space heaters marketing about how safe they are, no extreme temps at operating surfaces, vent openings, etc. and being impossible to start a fire. Yet I have seen same units cause melt down at the receptacle several times. Even occasionally when spec grade receptacle was used.

Listen like I said I get it it may not been properly installed I didn't install it many years ago so I could have not tighten things the way they should have been unfortunately but the bottom line is I want to know where to burn up like this would have something had to have been plugged into it?

 

[kwired]

Poor connection and heavy load, as others already said. I just wanted to add the poor connection could be one of two things:
1 . worn out receptacle not holding the plug tightly.
1a. too small of a cord used for the load, thus overheating and leading to #1.
2. loose screw/connection where the wiring attaches to the back of the receptacle.

Those are the only two possibilities unless it's something very abnormal. But you won't know which occurred until you open it up and look at the back.

Also, I like using 20A rated GFCI receptacles if they're on a 20A circuit. Consider doing that when replacing them. It won't help if problem 1a from above recurs, though.

Won't help if the cord cap that was used when it overheated gets plugged into the new receptacle either, even if it was a heavy duty plug, it's now compromised.

 

[kwired]

Listen like I said I get it it may not been properly installed I didn't install it many years ago so I could have not tighten things the way they should have been unfortunately but the bottom line is I want to know where to burn up like this would have something had to have been plugged into it?

There had to be load on it for it to heat up. This happens a lot, not just at receptacles but at any joint there is risk of this sort of thing happening if it is not a good enough joint. When it happens on the face of receptacle like that it likely was the connection between plug and receptacle that was weak. If it looks even worse on back side where supply conductors land, then possibly was that connection that was weak and heat migrated to the plug contacts as well. Seems less likely with a GFCI though as it will have contacts between input and output that operate when it trips, not as direct of a path for heat transfer as with a non GFCI receptacle.

 

[augie47]

Okay I get it but more than likely something had to have been plugged in correct

Yes !
(There is a very small chance of something else but 95+% it occurred with something plugged in)

 

[Jraef]

Well I ask my tenant he said he didn't plug anything in. It's just coincidental he's been asking for someone to install the car charger the last few weeks and now this is like that. Well I can't prove it so it is what it is.

But as Tortuga said, it wouldn’t matter. If he plugged into a 120V outlet, the Tesla would detect it as Level 1 and limit the current to 12A, which shouldn’t have caused damage. It was most likely a bad install (loose connection to the outlet), a cheap /defective GFCI, or water intrusion on the line side, so even though the GFCI tripped, it was still shorting on the line side and melted the outlet before the breaker tripped.

 

[Alwayslearningelec]

But as Tortuga said, it wouldn’t matter. If he plugged into a 120V outlet, the Tesla would detect it as Level 1 and limit the current to 12A, which shouldn’t have caused damage. It was most likely a bad install (loose connection to the outlet), a cheap /defective GFCI, or water intrusion on the line side, so even though the GFCI tripped, it was still shorting on the line side and melted the outlet before the breaker tripped.

So it could have happened w/o somthing plugged in?

 

[Elect117]

So it could have happened w/o somthing plugged in?

You are asking for a black and white answer to which there isn't one from the comfort of our homes. Like Augie said, there is a small chance of it happening without a load plugged in.

For all we know he was using the receptacle properly and it failed. There are numerous things that cause receptacles to fail. None of which would be the fault of someone using it as intended. Especially when the receptacle is outside where weather and sunlight can destroy things.