A light switch is used to open and close electrical current to help you turn on and off lights, ceiling fans, or electrical devices that are connected to equipment or outlets. Before you replace a light switch or install one, you have to make sure the switch matches the amperage rating and voltage of where it is being installed. The main light switches include: 15 amp light switches are ideal for residential locations. They should be connected to 14 gauge wire, which is found in most homes 20 amp light switches are ideal for commercial or industrial applications. 20 amp switches should be connected to a 12 gauge wire