I have a wireless tower site with an extensive grounding. I am picking up .2-.4 AC amps on the ground. I shut the whole site down and the electrode wire still had the .4 amp reading at the meter enclosure. We have determined that the reading is coming from the ground ring around the exterior of the shelter and tower. The chain link fence has every post with a welded ground attached to the ground system. We are picking up the reading on the 2 posts closest to the meter. Other posts closer to the tower had 0 amp reading. Is this caused by some kind of induction from other underground utilities? Is it possible that its from the antennas on the tower that are still powered by batteries when the AC power is shut off? I did notice that the amp reading on the ground drops when the rectifiers are shut off. I wanted to blame the rectifiers but I still had the .4 amp reading on the electrode wire when the site AC was shut off. Keep in mind that this site in on a hill top with approximately 50 ground rods and anything metal on the site has a welded or mechanical connection attached to the ground ring or system.