size breaker
size breaker
(OP)
I met a problem of sizing a three phase breaker. the current in each wire is measured around 50A, and it is well balanced in three phases. The breaker using now is 225A. Is it too large for the current load? how can I choose the breaker according to the current in wiring? Can I just use 50A or do I need multiply a factor?






RE: size breaker
1. Is there any motor load?
2. What is the largest motor in HP?
3. What is the starting arrangement of the motor?
4. Expected load growth?
5. Ambient temperature derating?
6. Altitude derating?
7. Sizes of conductor?
8. The largest rated circuit breaker or fuse downstream?
9. Does the breaker have a sensor?
10. What type of 225A circuit breaker is it?
11. Etc.
RE: size breaker
To size a new circuit, the NEC specifies several procedures, but mostly that the circuit is sized for at least 125% of the calculated load.
RE: size breaker
As DanDel poins out the NEC specifies several procedures... take the time to review these...
RE: size breaker
RE: size breaker