Hi,
I'm having intermittent problems with an exterior post lamp (light sometimes works, sometimes doesn't and it's not the bulb). I pulled back the wire from the fixture itself through the post bottom, but damaged that run while removing (~6'). Upon cutting and stripping that length back at ground level so I could splice in a new wire into the post (using an underground splice kit to mate the old/new), I noticed that each copper wire of my existing wiring (black, white, ground) has a green coloring such as you'd see on copper roofs exposed to moisture. I'm guessing that water's penetrating which might explain my intermittent problem, so I've halted my repair at the moment.
Does underground wiring normally turn green, or is water somehow penetrating where it shouldn't be? House is 15 years old. Thanks!