23 You might find yourself needing to install a switch to control a circuit in your car. There are several types of switches, and we’re not referring to color or size here. No, we’re referring to the number of poles and how many poles are connected at one time. SPST, SPDT, DPDT, latching, momentary, and so forth. Your best bet is knowing what switch to use in the first place. Once you know what these switches/toggles are and how they work, you’ll know exactly what you’ll need.