Various Types of Switches (electrical types)

Also known as: SPST

Description: Single pole single throw is the simplest electrical configuration for a switch. The SPST switch has two terminals and two positions. In the on position, the two terminals are connected. In the off position, the two terminals are disconnected.

Also known as: SPDT

Description: Single pole double throw switches have three terminals and two positions. One common terminal can be connected to either of the other two terminals, one at a time.

Facts: Some SPDT swiches have a "center off" position, in which none of the terminals are connected to each other.

Also known as: DPST

Description: Double pole single throw switches have four terminals and two positions. The DPST switch is equivalent to two single pole single throw (SPST) switches side by side whose handles are joined such that both SPST switches are thrown simultaneously.

Also known as: DPDT

Description: Double pole double throw switches have six terminals and two positions. DPDT switches are equivalent to two single pole double throw (SPDT) switches that are side by side whose handles are joined together such that both switches are thrown simultaneously.

Facts: Some DPDT swiches have a "center off" position, in which none of the terminals are connected to one another. DPDT switches can be wired to reverse the polarity of an electric current when thrown.