branch circuit

branch circuit [¦branch ¦sər·kət]

(electricity)

A portion of a wiring system in the interior of a structure that extends from a final overload protective device to a plug receptable or a load such as a lighting fixture, motor, or heater.

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Branch circuit

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). Thermal cutouts, motor overload devices, and fuses in luminaires or plug connections are not approved for branch-circuit protection and do not establish the point of origin of a branch circuit.

Branch circuits serving more than one outlet or load are limited by the National Electrical Code to three types:

• 1.  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.
• 2.  Circuits of 30 A may serve fixed lighting units with heavy-duty lampholders in other than dwellings or appliances in any occupancy.
• 3.  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.