I noticed my tooth brush wasn't charging one morning and none of the plugs in my bathroom were getting power, I went down to the circuit box and saw a flipped breaker so I flipped it back and it immediately tripped again. I tried it once more with the same result so I started to investigate the plugs in my house to see if anything was obviously wrong.
The external GFI on my deck had obvious signs of smoke on the siding so I disassembled the outlet and the entire back of the GFI blew out.
Is that a normal failure mode? Could it be a manufacture defect / installation issue?
There was obviously a lot of heat as the wire connectors appear scorched and the box is filled with a thick black soot.
Do I need to worry about additional damage to the wires beyond what is visible in the box or can I just remove the damaged wires and install a new GFI? Time to call an electrician?
Best Answer
This happens all the time if an exterior GFCI is not weather-resistant. I've never had a weather resistant GFCI go up in smoke.
Yes, they can be in a metal box, but they still should be marked WR (weather resistant) - this means the electronics inside are coated to reduce the chances of moisture causing exactly what happened with your GFCI.
If it had shorted to the box, the metal screw would have arced and tripped the breaker. If it had shorted on the load side, it would have tripped the GFCI. But, in this case, enough moisture got in and the electronics shorted and let the magic smoke out.
Last item on the list is that it should have an in-use cover or an extra duty cover, that allows a cord to be plugged in with the cover protecting from rain.
In this case, replace your GFCI with a WR rated GFCI and add an in-use cover to greatly reduce the chance of this happening again. In some jurisdictions the local ordinances require the outlet itself to be GFCI so it can be reset (not running cords inside because of tripping the GFCI in wet grass with an electric mower is the "why" the inspector told me).