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Branch-circuit conductors serving a single motor must have an ampacity of at least what percent of the motor's FLC?
At least 125% of the motor's full load current.
- 100%
- 150%
- 125% ✔
Why: Section 430.22 says size the conductors for at least 125 percent of the motor full load current. FLC comes from the NEC motor tables, not the nameplate.
Huh, didn't know that: Table 430.52 sizes this protection by device type: 150% to 300% of FLC for fuses and inverse time breakers, and 800% or more for instantaneous trip breakers.
Why was the electrician so excited to go shopping with his wife? She said they were going to the outlet mall.
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References
Answer: 125%. Section 430.22 says size the conductors for at least 125 percent of the motor full load current. FLC comes from the NEC motor tables, not the nameplate.
- EC&M: Motor Calculations Part 1 www.ecmweb.com/design/article/20897071/motor-calculations-part-1-motors-and-branch-circuit-conductors
Branch-circuit conductors that serve a single motor must have an ampacity of not less than 125% of the motor's FLC
Checked 2026-10-11. - NFPA: Report on Comments, 2023 NEC Article 430 (Table 430.52) docinfofiles.nfpa.org/files/AboutTheCodes/70/70_A2022_NEC_P11_SD_SRStatements.pdf
it shall not be necessary to first apply an instantaneous-trip circuit breaker at 800 percent or 1100 percent
Checked 2026-10-11.
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