Recently, the lone receptacle (a GFCI) in my bathroom started making a buzzing noise when something was plugged into it, then tripped. I turned off the power from the panel and pulled out the receptacle. I attached a photo.

There is a 14/2 and a 14/3 that enter the electrical box. The black wire from the 14/2 and the red wire from the 14/3 are connected with a wire nut. The Black wire from the 14/3 is connected to the line side, as are both neutral wires.

Two questions: Was this wired correctly? (The receptacle had been working properly for 10 years).

I assume there was some type of short circuit that made the neutral side to get burnt up like that (the hot side was OK). I see some bare spots on the neutral wires, but I'm not sure if those bare spots caused the short, or if the short melted the wire to create the bare spots. I can replace the receptacle easily enough (making sure to trim off the bare spots on the neutrals), but I want to make sure that I don't run in to the same problem again.

Any thoughts?

 

What size breaker. Bathrooms should be on a 20 amp breaker. A 20 amp breaker requires a minimum of #12.

 

Loose connection cause heat to build up and can cause melting.

 

The circuit breaker is 15 amp. The receptacle is 15A..

 

Your circuit may pre-date the requirements for a 20 amp circuit.

 

Don't worry about the wire size and such. Whats done is done and your breaker and wire size are good. If you ever do renos though, keep in mind you should change that to a 20A plug with 12 AWG wire.
Is the box burnt at all? A piece of wire may have came into contact with the box also.
When you put your new GFCI on, joint the neutrals along with a pigtail (small piece of white wire) and put the pigtail on the line side. You have a multiwire circuit and it is important to keep you neutrals connected at all times. Also check your panel for double breakers. Your black from the 14/3 is one circuit, and the red another circuit. They should be on a 2 pole breaker and not on two singles.

 

A 15 duplex receptacle is all that's necessary on a 20 amp circuit with #12 wire, no need to spend the extra money on a 20 amp device.

 

Thanks to all replies. I did not notice any signs that the box was burnt. Also, there is a single 15 amp breaker for the bathroom, but I don't know if both circuits in that box go to the same breaker. I will look into that.