althomas49
Electrical
- Mar 24, 2012
- 2
When selecting motor feeder circuit short circuit and ground fault protection, the code states:
You must provide the feeder with a protective device with a rating or setting not greater than the largest rating or setting of the branch-circuit short-circuit and ground-fault protective device (plus the sum of the full-load currents of the other motors of the group)
So if I use dual element time delay fuses for the branch circuits, but an inverse time breaker for the feeder, do I still use largest fuse rating for the calculation, or do I need to size the breaker as if the branch circuits were protected by inverse time breakers as well?
You must provide the feeder with a protective device with a rating or setting not greater than the largest rating or setting of the branch-circuit short-circuit and ground-fault protective device (plus the sum of the full-load currents of the other motors of the group)
So if I use dual element time delay fuses for the branch circuits, but an inverse time breaker for the feeder, do I still use largest fuse rating for the calculation, or do I need to size the breaker as if the branch circuits were protected by inverse time breakers as well?