Bought an order home with a 200 amp service. In the main panel is a 100 amp breaker that goes to a sub panel in a workshop out back. In the workshop there's two 20 amp breakers on one side and a two pole 30 amp on the other with no main cutoff/disconnect for the sub panel in the shop. None of the dozen plus 8 foot ancient florescent lights worked when we moved in but everything else ran fine. Recently, all power has stopped without any breakers tripping in the shop or on the main in the house. If I dial my meter down to it's lowest setting, I can read maybe half a volt, give or take in the shops sub panel. The 100 amp breaker still shows 120 volts. I have tried resetting the breakers, reseated the ones in the shop, trimmed off and redid the connections for the feeder wires - which I discovered were aluminum. I have traced the wires through the attic where they come out and down a wall into the ground seeing no signs of damaged lines or junctions. Short of digging up about a 100ft of yard or ripping open the shop wall, I can't find anything to explain it.
After some testing, I have found some current on the feed lines in the main for the 100 amp breaker to the workshop. It's small, and I register some current on the lines as they enter the ground. We're talking less than an amp. A non contact tester alerts that voltage is present on the lines entering the ground. No current on the lines in the workshop. However, the non contact tester is alerting along the ground, cinder block foundation and lower walls of the workshop.
Here's some pictures of the sub panel and the main.
Any advice would be greatly appreciated. What am I missing?1