Q. What are the NEC branch circuit rating requirements for individual appliances?
See answer below.
A. (A) Individual Circuits [Sec. 422.10].
The branch-circuit ampere rating for an individual appliance isn’t permitted to be less than the branch-circuit rating marked on the appliance [Sec. 110.3(B)]. The branch-circuit rating for motor-operated appliances must be in accordance with Sec. 430.6(A) and Sec. 430.22. A branch-circuit for an appliance that’s a continuous load must be rated not less than 125% of the marked ampere rating of the appliance [Sec. 210.19(A)(1)].
Example: What’s the calculated load for conductor sizing for a 4,500W, 240V water heater?
Solution: I = P ÷ E, where P = 4,500W and E = 240V I = 4,500W ÷ 240V = 18.75A Conductor Sizing = 18.75A × 125% = 23.44A Therefore, choose a 10 AWG conductor [Table 310.15(B)(16)].
Branch circuits for household ranges and cooking appliances can be sized in accordance with Table 220.55 and Sec. 210.19(A)(3).
(B) Circuits Supplying Two or More Loads [Sec. 422.10(B)].
Branch circuits supplying appliances and other loads must be sized in accordance with the following:
- Cord-and-plug-connected equipment must not be rated more than 80% of the branch-circuit ampere rating [Sec. 210.23(A)(1)].
- Equipment fastened in place must not be rated more than 50% of the branch-circuit ampere rating, if the circuit supplies both luminaires and receptacles [Sec. 210.23(A)(2)].
These materials are provided to us by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visit www.mikeholt.com/code.
