Low voltage circuit breaker symbol
Also called MCCB, Molded case circuit breaker, MCB
A low voltage breaker, moulded case (MCCB) or miniature (MCB), with a built-in thermal and magnetic or electronic trip unit.
What the low voltage circuit breaker symbol means
A low voltage breaker, moulded case (MCCB) or miniature (MCB), with a built-in thermal and magnetic or electronic trip unit.
ANSI and IEC symbols
A curved arc between two contacts, with the frame and trip ratings written beside it.
ANSI SVGWhere you see it
Low voltage switchboards, motor control centres and distribution boards.
What is written next to it
On a one-line, the low voltage circuit breaker carries its tag and its ratings: frame size, trip unit settings (long time, short time, instantaneous, ground fault) and breaking capacity in kA.
What gets checked at commissioning
Before the low voltage circuit breaker is energised, the test records usually cover: trip settings against the coordination study, primary or secondary injection, and mechanical operation. Each check is recorded against the tag, so the system can be handed over with its evidence. See commissioning software.
Related symbols
Frequently asked questions
What does the low voltage circuit breaker symbol look like?
On ANSI drawings: A curved arc between two contacts, with the frame and trip ratings written beside it. In IEC 60617: IEC uses one breaker symbol at every voltage: a switch with a cross. Trip units can be added as qualifiers.
Is the low voltage circuit breaker symbol the same in IEC and ANSI?
No. IEC uses one breaker symbol at every voltage: a switch with a cross. Trip units can be added as qualifiers. The IEC 60617 number is S00287.
Where is a low voltage circuit breaker used?
Low voltage switchboards, motor control centres and distribution boards.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016