Switches in Electrical Circuits: Pole and Throw

“Pole” indicates the number of circuits that one switch can control for one operation of the switch. “Throw” indicates the number of contact points. NO and NC contacts are single throw. Changeover contacts are double throw.

If one switch can control one circuit for one operation, it is a single-pole switch. If it can control two or three circuits for one operation, it is a double-pole or a triple-pole switch.

Single-pole, Single-throw	The switch contains one circuit with NO or NC contacts.
Single-pole, Double-throw	The switch contains one circuit with changeover contacts.
Double-pole, Single-throw	The switch contains two circuits with NO or NC contacts.
Double-pole, Double-throw	The switch contains two circuits with changeover contacts.

Use a multipole switch when you want to control more than one circuit at the same time.
 

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