On Wed, 3 Jun 2020 15:45:35 -0400, Todesco
wrote:

10 years ago I installed a post lamp in the front of my property. The
house builder left a 2" plastic conduit (maybe 100 feet) from the house
to the area where the post light was to be installed. I put a 4" square
plastic box at each end of the conduit as ground level. The house end
is no problem as it is in the asphalt driveway. At the house end, I
connected an underground "romex" to a breaker on the panel. At the
other end, I connected 2 underground "romex", one to the post light and
one to an outlet, some 25' away. Through the years, the outside box has
disappeared and I can't find it. I've tried raking up the leaf mulch.
Nope. I've also tried one of the non touch voltage testers. Nope.
I've tried a tracing unit connecting a signal to the power line and
snooping with the other end. Nope! I don't have a metal detector.
Not sure where to go from here. Any great ideas out there?

How far do you remember it being from the lamp post?. It might be
easiest to dig up the wire and follow it to the box if you think it is
pretty close. The downside is you might damage the wire but if you
have it dug up anyway, it is just a piece of UF you have to replace
along with whatever you are planning to do. I doubt a metal detector
would help much if this is a plastic box. It might see the copper wire
but maybe not. This is supposed to be 24" down if it is not on a GFCI.