Is My MCB Not Working Properly?
Marginal Overcurrents:
At mild or marginal over currents it’s probably working just fine. The latitude for tripping is pretty wide. See the table below:
At mild or marginal over currents it’s probably working just fine. The latitude for tripping is pretty wide. See the table below:
Interpretation of table
Say you have a 16 amp breaker. Assume a load of 18 amps.
The MCB should either NEVER trip, or trip within 1 hour. So the breaker may function day in and day out with no spurious tripping.
If the breaker ‘sees’ 20Amps it should trip within 2.5 Minutes to 1hour.
Most electricians have no time or the capacity to thoroughly test the equipment, so if an over-current is detected then breakers are simply replaced to maintain safety standards.
Before a miniature circuit breaker is condemned check if the MCB is a B, C or D type and compare the current vs. tripping curve accordingly.
Say you have a 16 amp breaker. Assume a load of 18 amps.
The MCB should either NEVER trip, or trip within 1 hour. So the breaker may function day in and day out with no spurious tripping.
If the breaker ‘sees’ 20Amps it should trip within 2.5 Minutes to 1hour.
Most electricians have no time or the capacity to thoroughly test the equipment, so if an over-current is detected then breakers are simply replaced to maintain safety standards.
Before a miniature circuit breaker is condemned check if the MCB is a B, C or D type and compare the current vs. tripping curve accordingly.