A branch circuit is the portion of an electrical wiring system that extends beyond the final, automatic overcurrent protective device (circuit breaker
or fuse), which is recognized by the National Electrical Code for use
as a branch-circuit overcurrent protector, and that terminates at the
utilization device (such as a lighting fixture, motor, or heater).
Branch circuits serving more than one outlet or load are limited by the National Electrical Code to three types:
Circuits of 15 or 20 A may serve lights and appliances; the rating of one portable appliance
may not exceed 80% of the circuit capacity; the total rating of fixed
appliances may not exceed 50% of circuit capacity if lights or portable
appliances are also supplied.
Circuits of 30 A may
serve fixed lighting units with heavy-duty lampholders in other than
dwellings or appliances in any occupancy.
Circuits of
40 or 50 A may serve fixed lighting with heavy-duty lampholders in
other than dwellings, fixed cooking appliances, or infrared heating
units.
