What caused this?


Old 04-05-19, 06:37 PM
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What caused this?

There are 2 bathrooms on the same 20 amp circuit in ~20 year old house. In bathroom room 1 is the standard outlet shown in the attached photos and about 3 feet away from it is a GFCI outlet. Bathroom 2 has a single standard outlet. While a hairdryer was being used in bathroom 2, I heard a buzzing coming from the standard outlet in bathroom 1. Turned off the breaker and found what you see in the photos - what I presume to be an arc fault. I also checked the bathroom 2 outlet the hairdryer was pluged into and see no problems - for reference, I'm guessing it's the last receptacle on the circuit since it had only 1 black and 1 white wire attached.

Obviously I will be cutting back to fresh wire and installing a new outlet to replace the bad one in the photo. Although I'm a lifelong DIYer, most of my experience is non-electrical so my knowledge in this area is basic. Therefore, I'm hoping to learn what is likely the root cause here. Can basic outlets like this somehow develop such a problem with age or is there something else going on?

Thanks in advance for any insight you can offer.

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Last edited by PJmax; 04-05-19 at 07:23 PM. Reason: resized pictures
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Old 04-05-19, 07:18 PM
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Welcome to the forums.

I see some corrosion on the copper wiring which usually signifies dampness but that isn't the main problem there. You had a loose screw(s) and the wire got hot. Clean the wires..... replace the receptacle and you should be fine.
Old 04-06-19, 08:58 AM
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Thanks for also pointing out the corrosion. I noticed it as well but am confident there's no water or dampness in the wall. So, since it's only on that 1 wire (and none of the others) maybe the arcing somehow made it more prone to corrosion and the bathroom humidity was enough to trigger it. Anyway, thanks for the explanation about the main problem. When I pulled out the receptacle nothing seemed loose, which left me slightly baffled as to the cause. But after reading your reply, I looked more closely and although the wire with the melted insulation was wrapped around the screw well enough to keep it on, the screw itself wasn't screwed down. So, the movement in the wire caused the arcing = problem solved. Wanted to come back and confirm that in case it might help anyone else who comes across this thread in the future. Thanks again PJmax for your insight. Much appreciated.
Old 04-06-19, 10:58 AM
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Copper can also oxidize from overheating as well. So, the corrosion is not necessarily from dampness.
If you have enough wire length, cut wire with burnt insulation back to good section.
If not, just wrap it with electric tape and clean oxidized copper with sand paper.
Old 04-06-19, 11:57 AM
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lambition, good to know. Thanks!

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