This winter my lamp post which has been in place for about 30 years just stopped working. I checked the switch to see if it went bad, and it is ok. I could not detect any power at the fixture head. Last week, I noticed the three florescent bulbs flickering very dim when I threw the switch. I pulled the fixture and checked the wires for power. I was only getting partial voltage, approximately 15 volts. I dug the wire up as far as I could see it since it runs under a walkway and cut it to test the power. I had the same power. At this time, I have to assume there is a break or serious corrosion somewhere in the wire between the house where I dug the wire up. I won't be able to do anything until spring. The wire is Romex and when I strip it back, the copper is green...not a good sign!

Is there any way or tool to see where the wire is running and where it is damaged? I hate to call an electrician at this time knowing that I may have to do some serious digging and jack-hammering. I just don't want to have him come out, find the problem, then have to come back again?