ELECTRICALResources / Electrical symbolsUpdated 29 Oct 2026

Switch, push button, relay and contact symbols

Switches, push buttons, relay coils and their contacts are the language of control circuits. Every contact is drawn in its normal state: with the coil de-energised and nothing pressed.

SymbolANSI / IEEEIEC 60617What it is

SPST switchS00227A single pole, single throw switch: one circuit, opened or closed.

SPDT switchS00230A single pole, double throw switch connects one common terminal to one of two others.

Push button (NO)A momentary switch that closes only while it is pressed.

Push button (NC)A momentary switch that opens while it is pressed.

Relay coilS00305The coil of a relay or contactor.

Normally open contactS00227A contact that is open while the relay is de-energised and closes when the coil is energised.

Normally closed contactS00229A contact that is closed while the relay is de-energised and opens when the coil is energised.

Switches and relays: ANSI and IEC

Here the two standards differ the most. US ladder diagrams draw a normally open contact as two parallel lines and a relay coil as a circle; IEC 60617 draws contacts as a hinged blade and a coil as a rectangle.

A relay coil and the contacts it operates share one reference designator (CR1 in US practice, K1 in IEC), however far apart they sit on the drawing.

Frequently asked questions

Which switches and relays appear on a electrical schematic?

This legend covers SPST switch, SPDT switch, push button (NO), push button (NC), relay coil, normally open contact, normally closed contact. Project legends may add more.

Are these symbols different in IEC and ANSI?

5 of the 7 are drawn differently. Each symbol page shows both forms side by side.

Can I download these symbols?

Yes. Each symbol page has free SVG files, and the hub has printable PDF charts.

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Switches and relays: ANSI and IEC

Frequently asked questions

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