Hello all, We just moved into a new house and the previous owner ran two 20amp circuits with 15 amp receptacles in the garage via conduit. There are four wires, red, black, white, green shared between the two circuits. He shared the neutral between the two circuits. Is this safe? Legal? Can a ground be shared between two(or more) circuits? I want to add another circuit to the garage as well (20amp). If multiple circuits can share a neutral, is it limited to two? The red is stripped in a couple junction boxes so I'll be pulling new wire for that one as well. (I found these as the receptacles were not tight and I pulled them out to figure out why.) Thank you!