Two GFCIs

[Bozack]

hello all

I have a new house and the outdoor outlet is a standard WR 15a plug fed from an internal GFCI, I attempted to change the outdoor outlet to GFCI but neglected to switch the internal GFCI to have both feeds on the line side, when I installed the GFCI outside it came up and tested ok but about a week later I noticed it was tripped, the red light was blinking (hubbel) and there was a slight amount of black residue in the water tight enclosure.

I promptly removed the GFCI and inspected the wiring which all seemed fine as well as beyond the black material and the popped unable to reset state the GFCI was intact (no signs of melting or damage)

I replaced the outlet with the standard WR outlet again and now everything seems fine

From what I have read it seems what I did was redundant but wanted to know why people thought the outlet would have failed and if there is anything else I should be concerned with?

Thanks

 

[Stuff]

Feeding a GFCI to a GFCI normally works but is not recommended. Does the outside receptacle trip the inside GFCI with a tester?

Black residue means something was in there.

 

[Sponsor]

 

[Bozack]

Feeding a GFCI to a GFCI normally works but is not recommended. Does the outside receptacle trip the inside GFCI with a tester?

Black residue means something was in there.

I have a plug in tester and after swapping it things were ok, they are building a house next to mine so it’s possible they pulled power out of my outlet for some of their tools when I was away and it killed the outlet

 

[Jadnashua]

As I see it, you had two choices:
- use a 'plain' receptacle, protected by the interior GFCI, or
- relocate the wires on the internal GFCI to feed the exterior one from the line side verses the load side and use a GFCI outside as well.

Depending on how far you are from the bay, the precipitation might have some salt in it...that can be problematic, and some water-tight boxes aren't all that water-tight when you have something plugged into them.

Putting them in series can sometimes be a problem.

 

[WorthFlorida]

Be sure the the outside GFCI is feed from the line side of the inside one.

A note about GFCI and heavy loads. From my experience a 15 Amp rated unit will burn out when heavy tools are plugged in such as power hammers, compressors, etc. maybe it burned as you suggested by other workers.

Most outdoor fixtures are rated for damp locations and are not necessarily water tight. Wind drive rain or even a sprinkler system can drive moisture inside a GFCI. There are GFCI rated for damp locations. I used to plug in plastic child protectors and it worked from getting water inside of it. Plug in your tester and remove it and check for water on the plug blades.