A government building is to be served by a 300A, 120/240V single-phase feeder. The maximum number of 20A, 120/240V branch circuits that can be supported is:
- AExactly 12 circuits
- The maximum cannot be determined from these ratings alone
- CExactly 18 circuits
- DExactly 21 circuits
Where to look it up
Explicit exercise assumptions; not a universal code requirement.
Why B is correct
Dividing 300 amperes by a 20-ampere branch-circuit rating gives 15, but circuit ratings do not state actual or calculated loads. The number of circuits that can be supplied depends on load calculations, their arrangement and applicable equipment limits. The given ratings alone cannot establish a maximum count.