Hi, congratulations on the home and central vac! The single wire turns the suction unit in the garage or basement on and off. When the wire is shorted through a hose handle switch or touching the two small contacts in the wall port hole the suction starts. A nozzle is powered when you have an electric kit with a pigtail electric hose. The wires are all hidden in the hose and at the wall end of the hose an 8ft cord extends to plug into the closest electrical wall socket. There are also air turbine brushes available which spin solely on the power of the air coming through it. These are good for minimally carpeted homes whereas the electric kits are best for wall to wall carpeted homes.