SLDResources / SLD symbolsUpdated 29 Oct 2026

Circuit breaker and switch symbols

Switching devices open and close the circuit. What each one can do sets its symbol: a circuit breaker interrupts fault current, a load break switch interrupts load current, a disconnector only isolates, and a fuse melts.

SymbolANSI / IEEEIEC 60617What it is

Circuit breakerS00287A circuit breaker opens and closes the circuit and interrupts fault current, tripped by its protective relays or its own trip unit.

Draw-out circuit breakerS00287A circuit breaker on a truck that racks out of the switchgear, which isolates it and lets it be removed for maintenance.

Low voltage circuit breakerS00287A low voltage breaker, moulded case (MCCB) or miniature (MCB), with a built-in thermal and magnetic or electronic trip unit.

Disconnect switchS00288A disconnect switch isolates a circuit so it can be worked on.

Load break switchS00290A load break switch can open and close normal load current and also isolates, but cannot clear a fault.

Earthing switchS00288 + S00200An earthing switch connects a de-energised circuit to earth so it is safe to work on.

ContactorS00284A contactor is an electrically operated switch for frequent switching of loads, usually motors.

FuseS00362A fuse protects a circuit by melting when the current is too high for too long.

Fused switchS00370A switch and fuses in one unit: the switch isolates and switches load, the fuses clear faults.

Automatic transfer switchAn automatic transfer switch moves a load from its normal supply to a standby supply, such as a generator, when the normal supply fails.

Switching devices: ANSI and IEC

IEC 60617 builds every switching device from one switch blade and marks what the device can do at the fixed contact: a cross for a circuit breaker (S00287), a bar for a disconnector (S00288), a half circle for a contactor (S00284). US one-lines draw medium voltage breakers as a square marked 52, low voltage breakers as an arc and disconnects as a plain blade.

Telling them apart matters on site: only a breaker can clear a fault, a load break switch can open load current, and a disconnector must only be opened with no current flowing.

Frequently asked questions

Which switching devices appear on a single line diagram?

This legend covers circuit breaker, draw-out circuit breaker, low voltage circuit breaker, disconnect switch, load break switch, earthing switch, contactor, fuse, fused switch, automatic transfer switch. Project legends may add more.

Are these symbols different in IEC and ANSI?

9 of the 10 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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Switching devices: ANSI and IEC

Frequently asked questions

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