Noncoincident Loads: Larger of Heating vs A/C (NEC 220.60)
Applies NEC 220.60: where two loads (electric heat vs air-conditioning) are unlikely to run at the same time.
Example
You enter
- Load A - e.g. electric heat (VA) 9000
- Load B - e.g. air-conditioning (VA) 6000
You get
- Counted load (VA) 9000
- Omitted load (VA) 6000
Checked against published worked examples from: NEC 2023 (NFPA 70).
Details, formula, and sources
ScopeThe service calc carries only the larger and omits the smaller; the exception adds both where they operate simultaneously (a heat-pump compressor with supplemental strip heat). The AHJ judges noncoincidence.
Formula or tablecounted = both_can_run ? load_a + load_b : max(load_a, load_b); omitted = both_can_run ? 0 : min(load_a, load_b).
Source and editionNoncoincident loads, NEC 2023 220.60, with the simultaneous-operation exception, by name.
Free accessNEC is free to read at nfpa.org/freeaccess. Where two loads are unlikely to be in use at the same time, only the larger is counted; the exception adds both where they operate together (a heat-pump compressor with supplemental strip heat).
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namesload_a_va, load_b_va, counted_va, omitted_va
- Larger-of rule the smaller of two noncoincident loads is omitted from the service/feeder calculationNEC 220.60
- Simultaneous exception both loads are counted where they can operate at the same time; the AHJ judges noncoincidenceNEC 220.60 exception