Install a 110-volt polarized electrical plug by connecting the white wire to the steel or chrome-plated screw, the black wire to the brass screw and the bare ground wire, if it is used, to the green screw. If installing a plug on an appliance where the wiring is not color coded, observe the connection before cutting the old plug from the appliance. The smaller side of the outlet is the hot wire and the wider side is the neutral wire.
Polarized outlet have different sized openings on so two pronged plugs fit only one direction. If installing an outlet, follow the same color code. If adding a switch for the plug, install it on the black or hot wire so shutting off the switch prevents the flow of electricity to the plug. Grounded plugs do not need the wider plug, because the ground post only allows the user to insert the plug in one direction.
Many older homes do not have polarized outlets. Appliances such as lights and motors often work the same regardless of the direction the user inserts the plug. However, with sensitive electronics such as computers, cell phones and digital devices, following the plug priority becomes more important. Determine if an appliance requires a polarized plug by reading the user’s manual.