That happens just as you described. You did mention "outdoor box" if you are
referring to an outdoor weatherproof box such as type "FS" or Bell box, the
threaded knockouts must be sealed with suitable compound to exclude water
entry and by current code the covers should be "while in use" type, which
prevents water entry when something is plugged in


wrote in message
...
A relative called me and said they had a breaker that kept tripping.
I went and looked and found an outdoor outlet that was in a suitable
outdoor box with a protective cover (that closes over the outlet).
The face of that cover was all black and charred, the foam in the
cover was burned on half of the cover as if it had burned. When I
opened the box I found the outlet was all charred from the side by the
hot wire to the cover plate. I could see that water had been entering
the box and corrosion on the screws. From what I was able to gather,
the corrosion allowed a certain amount of electricity to arc over the
box cover which in turn caused carbon tracking on the outlet itself,
and at one point it must have gotten quite hot to burn away the foam
on that side of the cover.

Does this seem to make sense as far as what happened? The breaker
would trip as soon as I turned it on as in a dead short, yet there was
no noticable direct short such as a bared wire touching the box.
Therefore it appears it was only the carbon on of the burned away
outlet and corrosion that formed the short to the box. I find this
hard to believe and it looks as if could have been a serious fire
hazzard. It sure looks like it actually burned under the cover.

I am just asking if anyone can explain how this occurred. Obviously
water was leaking into the box. I replaced the outlet with a new GFI
outlet and installed a new cover. The box itself was still ok.
Besides the gasket that came with the new cover, I applied silicone
around the top and sides of the cover to insure no more water leakage.
Those gaskets dont seem to be adaquate in my opinion.

Alvin