Electrical / Electronic Switches Abbreviation and Symbols

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Electrical / Electronic Switches Abbreviation and Symbols

The following chart provides several common electro-mechanical switch drawing symbols and abbreviations. The switch illustrations may be used on mechanically actuated switches, membrane switches, or circuit mounted switches.

Abbreviation	Nomenclature	Description	Switch Symbol
SPST	Single pole, single throw	Two terminals connected together or not connected.
SPDT	Single pole, double throw	A simple change form switch: Common is connected either to L1 or to L2.
SPCO	Single pole changeover or Single pole, centre off	Identical to SPDT. Suppliers may use SPCO for switches which are stable in off position while position the center and SPDT for those which do not.
DPST	Double pole, single throw	Identical to two SPST switches mechanical connected.
DPDT	Double pole, double throw	Identical to two SPDT switches mechanically connected.
DPCO	Double pole changeover or Double pole, centre off	Identical to two DPDT. Suppliers may use DPCO for switches which are stable in off position while position in the center.