melted receptacle mystery

[charles]

The attached photos show the plug of a radiant space heater and the Cooper receptacle it was plugged into. The receptacle was backstabbed and the wire on the burnt side was loose, but I don't know if the looseness was a cause or an effect of the problem. I think also that the polarity of the wires was reversed by the installer. What's weird is that the circuit is protected by a Siemens AFCI breaker that didn't trip. When tested at the service panel 2 out of 3 AFCI breakers seem slow to react.

So what's to blame? The installer, the space heater, the receptacle or the breaker?

[MarkMc]

It's all suspect . If one recept is wired wrong then it wouldn't be unlikely that others are as well. Qualified inspector should be employed to verify other circuits and devices are up to snuff. Space heater use get blamed for most fire deaths in winter, though the fault may not lie in the the heater itself or it's proximity to flammable materials.

[dgbldr]

The breaker would be the least likely root cause.
The localized high temp condition and the breaker not tripping indicates a local high resistance condition. Not overcurrent.
The backstabbed wire stub is not burned, so that connection is not suspect.
Looks like the contact between the plug blade and receptacle spring clip was poor. Maybe it was arcing, maybe not. Could be looseness, oxidation or contamination of the blade or clip.
Polarity has nothing to do with it.
You can easily put a new plug on the appliance cord and test it for current draw. I suspect you won't find anything abnormal there.

[MarkMc]

Polarity has nothing to do with it.

Unless it did, and it can; we polarize for a reason. Since we don't know what the heater unit is and whether or not is has any internal damage only a um, silly person, would make the claim that it had nothing to do with it; that's just sloppy thinking.

[dgbldr]

On the contrary, a little bit of electrical knowledge would fully warrant my statement. Easy enough to settle.
Please describe a situation where reverse polarity would cause the described result. Feel free to use your vaunted imagination but stay within the constraints of the OP description and pictures.

[Dutchman]

I see the back stab but I also see (what looks like) a stub of wire with black housing that would seem to be a hot wire, this may be suspect but who knows.

Polarity shmarity, if this was /is s simple 110V circuit with modern wiring (and the wiring was correct) what could the problem be other than the cheap Chinese piece of junk appliance connected to it?

What's inside that appliance cord?, everything okay there?

And no DG, it's impossible for McCryptic to reply back without blaming this on Obama or someone else!

[Dutchman]

Ah, looking at it again, the fault is on the neutral side....somebody wired something wrong.

[MarkMc]

On the contrary, a little bit of electrical knowledge would fully warrant my statement. Easy enough to settle.

Show me where reversed polarity is called safe, by anyone, and the reasons why it's considered safe. I'll patiently await sparky.

The answer of course is electricity and incompetence are most likely to blame, along with Bob.

[dgbldr]

Ah, looking at it again, the fault is on the neutral side....somebody wired something wrong.

Nope. Any miswiring that resulted in a short or overcurrent would a) trip a breaker and if there were no breaker would b) result in overheating of the current return path (the hot or ground blade/clip, depending on how badly miswired). Current going into one terminal must return through one of the other 2. You can plainly see the other 2 did not overheat.

Miswiring is certainly possible and likely, but is not the cause of that meltdown.

[dgbldr]

Show me where reversed polarity is called safe, by anyone, and the reasons why it's considered safe.

Fail. Even Adam ****t can do better than that.

I didn't say reverse polarity is safe. I said it had nothing to do with the meltdown described in the OP. Let me put it in more easily understandable terms for you. Nuclear war did not cause this event. Nuclear war is NOT safe.

Still waiting for you to tell me exactly how reverse polarity can cause the meltdown. Take your time.

[MarkMc]

Fail. Even Adam ****t can do better than that.

I didn't say reverse polarity is safe. I said it had nothing to do with the meltdown described in the OP. Let me put it in more easily understandable terms for you. Nuclear war did not cause this event. Nuclear war is NOT safe.

Still waiting for you to tell me exactly how reverse polarity can cause the meltdown. Take your time.

Why we do have standards for maintaining polarity? Please enumerate the hazards, and while you're in that enumerating mood go forth to where I said it was explicitly/exclusively the cause of the condition depicted. Your deflecting is suspect.

[dgbldr]

Fail again. Not letting you off the hook

Unless it did, and it can;

Tells us how it can.

[Dutchman]

To the OP, has any other appliance made this device go Chernobyl?

[m beezo]

I see it is back stabbed and the screws you would tighten down around a wire are all out at the full length. Could it have been in a metal box and the hold down screws made contact with the metal box and caused arcing.

I do not really know why I do it but any metal box I install a device into if I am backstabbing which I seldom do, or if I am attaching the wire under a screw I always tighten the other screw down whether it gets a wire under it or not. And then the device gets a couple of wraps of tape around it.

[MarkMc]

Fail again. Not letting you off the hook



Tells us how it can.

What hook? You fail again to answer that simple easy question. Please tell us all why we have polarized plugs? Now for a harder question point out where I claimed it was the cause or the most likely cause of what the picture indicated. For bonus points show us the heater and it's wiring as well as the rest of the circuit that receptacle is in. Remember, if it's easy you won't make us wait long. Stop wiggling and start showing.