Outdoor GFCI shorted and caught fire, how to check if wiring is safe?

Question

Earlier today I was spraying down the exterior of my house in the general vicinity of the outdoor GFCI. It turns out the weatherproofing around the box was...less than good and water got in which appears to have caused a rather nasty short.

I killed the power to the house while investigating the burning smell and after finding this I immediately pulled it out and capped the wiring. After closer examination, the circuit breaker did in fact trip, but I have no way of knowing when. Power is back on, and when resetting the breaker for that circuit it didn't immediately trip, though I have turned the breaker back off in the mean time.

The wiring is obviously burnt up to a certain point and I recognize that needs to be cut out, but how far up does one need to go?

I'm looking for an electrician to come take a look at it, but in the mean time my question:

How do I know if this circuit is safe to turn back on? Unfortunately it's not dedicated, and appears to have the interior hallway lighting and outlets on it.

Answer 1

I would just cut the wires up to the point where you can see copper and the insulation feels ether soft or "crispy". If wires become too short, you can pigtail it to extend length. From the pictures, it looks like only the first couple of inches that got burned and breaker did it's job well.