Breaker Sizing
Continuous-load 125 percent rule.
Example
You enter
- Load current (A) 16
- Continuous true
You get
- Required ampacity 20 A
- Next standard breaker 20 A
Checked against published worked examples from: NFPA.
Details, formula, and sources
Formula or tableOCP = 125% × continuous load + 100% × non-continuous load (NEC 210.19(A) / 215.2(A)(1) / 215.3); next-standard-size rule per NEC 240.4(B); standard sizes per NEC 240.6(A).
Source and editionNEC 2023 (NFPA 70).
Free accessFree read-only access at nfpa.org/freeaccess.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namesload_A, continuous, required_A, next_standard_A
- Standard breaker sizes NEC 240.6(A) ladderNEC 2023
- Continuous-load definition load ≥ 3 hoursNEC 100