A 220 volt circuit by code needs a 3 wire with ground in it. Nothing runs on a true 220 so its actually made up of two 110 volt circuits with a common neutral and ground. The red and black are your hots each carrying 110 volts. The white is your neutral and the copper or green wire is your ground. Either red or black wire to either the white or ground will show 110 volts and across the red to black wires will read 220 volts
