I thought we had an underground problem. So, I done a fault locate and found 2 spots with leakage to earth. I dug them up only to find minor nicks in the cable and fixed them. After further investigation and watching voltages and current on cables, I think it is just a case of voltage drop.
I got out my measuring wheel and determined it is 400+ feet from main distribution panel to building with the issue. I decided plug all the information into my electri-calc. With the 400', #2 AL, 121 volts, and 11 amps....it tells me that i have a VD of like 4.4 volts. That is about what I'm seeing.
BUT, I still don't understand why equipment in the house is affecting the light in this building. The voltage drop is on the service wire feeding the building only. No effect on the main panel. And there is no other load on in this building at night when the light is on.
