Easy installation on any single duplex or dual duplex GFI outlet. Remove the "hot" black wire from the GFI outlet and connect to the VendaVolt black wire with supplied wire nut. Next attach the white common wire to the GFI silver screw lug in parallel with the existing white common wire. Last step is to connect the red wire from the VendaVolt to the "hot" screw lug of the GFI outlet.