3 Phase Circuit Breaker Sizing Calculator. For example the full load current of a 5 hp motor at 460v is 7 6 amps. Cable sizing software select size and manage your power cables using mycableengineering.
Breaker size must be rated for a minimum of 125 of the full load current of the motor it is protecting rounded up to the next standard breaker size. Cb current should not be lower nor highest but 125 of. For 3 phase loads you divide the va by the nominal voltage and by the square root of three approximately 1 732.
If your total 3 phase load in a 480v system is 50 000va what size breaker do you need.
For example the full load current of a 5 hp motor at 460v is 7 6 amps. Therefore it is good practice to size the breaker at 15 amps. For example the full load current of a 5 hp motor at 460v is 7 6 amps. How to size circuit breaker for three phase motor.
