Switched off main to attach ground wire to two outlets in garage (one normal, one GFCI), now separate circuit to attic (feeding one overhead switchable light, one receptacle, doorbell, and AIR HANDLER) will not power up. Breaker is on (not tripped). I have switched off each individual breaker in box, then main off and on, then each individual back on, still nothing. I have tested breaker at panel, each side of 220v breaker reads 120V when breaker is on, 0v when breaker is flipped off. Conduit run into attic (before branching to switchable light, receptacle, and air handler) is not hot, with breaker in ON position. Have not tested for continuity yet. Suggestions?
"B" in photo is breaker/circuit in question
There seems to be some confusion as to the issue I am now having. The initial problem was a shock coming from an ungrounded, non-GFCI outlet in the garage, to which the amp was plugged in. THAT receptacle was downline of a GFCI receptacle, which also had no ground wire attached. I shut off the main, attached ground wires (that were already present in the outlet boxes), and now there are no issues in the garage. Amp/guitar no longer shocks. When I turned the main back on, that is when I had a new problem in the attic, a different location in the house (with one receptacle, one overhead light on a switch, and the HVAC air handler), which does not include the receptacles in the garage, which are currently operational. Tonight I will test every receptacle in the house, and report back. As for the breaker/amp issue, @Harper I can just switch the main off and replace the 30a breaker with a 20a, and the light, receptacle, and air handler will function properly, assuming there are no other issues?