We purchased a building about a year ago, which has a 120/220 single phase circuit, plus an additional 480v 3 phase delta circuit. After gutting all the unneeded stuff an rewiring everything to get a 480v 3 phase Y circuit, we noticed the old delta circuit had a hot ground to our water pipes. So you could literally stick the voltmeter into the ground and the other to any copper pipe in the building, and get a 120v circuit. Needless to say, we called and had the delta disabled that day