"burn" marks on receptacle?


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Old 06-19-10, 07:13 AM
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"burn" marks on receptacle?

I was checking out the possibility of putting three new receptacles onto a 15 amp bedroom circuit that currently only has a ceiling fan/light and one duplex receptacle. The current receptacle (installed three years ago by an electrician--with new wiring) has a couple of light brown/gold marks that look like the beginnings of "burn" marks at the opening of one set of slots where a plug goes. There's currently a surge protector plugged in there that has only a computer and printer on it. The other set of slots has a computer router, and it looks fine. What might be causing this and is there anything that needs to be done about it?

Thanks in advance!
 
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Old 06-19-10, 07:37 AM
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That could be the start of a potential problem. Heat is caused by loose connections or a high resistance connection. I would turn off the power and look for any loose connections. Move the wires to the screws on the sides instead of the backstabs, if used.

The blade tension might also be loose. If the plug pulls out easily you should replace the receptacle.
 

Last edited by pcboss; 06-19-10 at 10:27 AM.
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Old 06-20-10, 06:41 AM
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I checked and there are no loose connections and no backstabs. Blade tension also seems good, but the surge protector is a three-prong, so it's hard to tell as easily as you would be able to with a two-prong.

Could it be that he used an older receptacle that just needs replacing?

Why does one set of slots on the receptacle look like this and not the other? Is it possibly something to do with the surge protector plugged into it?

What else causes high resistance?

Thanks for any other ideas!
 
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Old 06-20-10, 06:49 AM
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Further info: There was some joint compound dust and other debris in the box. Can cleaning this out eliminate the problem. Can dirty contacts cause high resistance?

Thanks again!
 
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Old 06-20-10, 07:07 AM
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The joint compound dust could have acted as an insulator.

A high resistance path would not conduct electricity as well as a low resistance path with good metal to metal contact.
 
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Old 06-21-10, 04:50 PM
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It's highly unlikely that enough dust could have gathered (especially without being scraped off by the prongs) to cause problems. When you say 'burned'.. Is the plastic melted/discolored/deformed? Or is it just a 'soot track' where something might've shorted across the prongs?

I would just replace the receptacle and be done with it though.
 
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Old 06-21-10, 05:31 PM
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No, it wasn't a soot track. Definitely discolored plastic, kind of like a marshmallow just starting to get golden brown in the camp fire.

The joint compound dust was in the screw terminals, not in the slots.

I replaced the receptacle and taped around it to cover the screws terminals to prevent any possible future dust/debris from accumulating there.

Thanks, everyone!
 
 

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