On/Off Switch

There's not a whole lot to say about the simple on/off switch. Although they come in different styles, they all simply open and close the electrical circuit. An ohm meter (when disconnected) or the proper volt meter (when connected) will test the switch. Almost any switch, if it physically fits, will work as a replacement for a switch controlling only a 120 volt circuit. However, some switches control a 12 volt circuit directly, or indirectly, and may require a switch rated at a higher than normal amperage.

Triple Pole, Double Throw Switch

The triple pole, double throw switch is used in one way or another on most refrigerators that are manually switched between 12 volt and 120 volt. Seeing how the switch works in the above picture is relatively simple, but seeing the switch in a wiring diagram demonstrates its usefulness and its relatively complex wiring. The best way to test the switch is by removing all the wires and testing the terminals with an ohm meter while in each of its three positions. It would be very wise to draw a wiring picture of the switch before disconnecting the wires, however.

Probably the most important thing to note about the wiring of this switch is that the two voltages (120 volt and 12 volt) are never allowed to meet. Even though a switch that is improperly wired and allows the two voltages to meet may not always create sparks, it will cause problems elsewhere. If the two voltages simultaneously have a common wire in the refrigerator, the voltages are tied together throughout the RV.