Circuit breaker symbol
Also called MCB, Miniature circuit breaker, Breaker
A circuit breaker opens automatically on overcurrent and can be reset. On schematics it is shown in its closed or normal position as the drawing defines.
What the circuit breaker symbol means
A circuit breaker opens automatically on overcurrent and can be reset. On schematics it is shown in its closed or normal position as the drawing defines.
ANSI and IEC symbols
Where you see it
Protection of final circuits, control supplies and motor feeders.
What is written next to it
On a schematic, the circuit breaker usually carries its designator, rated current and curve, such as CB1 10 A or Q1 C16.
What gets checked before energising
Before the circuit is energised, the checks on a circuit breaker usually cover the rating and trip curve against the drawing, and that it trips and resets. Each check is recorded against the tag, so the circuit can be energised and handed over with its evidence. See the ITR guide.
Related symbols
Frequently asked questions
What does the circuit breaker symbol look like?
On ANSI drawings: Two terminals with an arc above them. In IEC 60617: A switch blade with a cross on the fixed contact.
Is the circuit breaker symbol the same in IEC and ANSI?
No. A switch blade with a cross on the fixed contact. The IEC 60617 number is S00287.
Where is a circuit breaker used?
Protection of final circuits, control supplies and motor feeders.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016