We do primarily residential work, but we do deal with some commercial. I was installing a 3 phase condenser and notified my boss that there was no ground coming into the disconnect box. He told me 3phase units do not need a ground. This doesn't make any sense to me. This doesn't make any sense to me. I fired the unit up, but I am worried we may be held liable if someone get hurt. Have any of you heard of not grounding 3phase units. It would be a new one for me.