Once you receive your Del spa ozonator you will need to install it. The Del MCD-50 with a Amp cord is sold with loose wires. This is due to the fact that different spa control boxes are sold with different wire configurations. The Del MCD has a black active wire, white neutral wire, and green ground wire. I contacted Balboa to find out what the wire configuration was for the VS501Z Control Box. They stated the active was the top, skip the second, neutral was third, and ground was bottom.