Feeder/Service Neutral Demand Load (NEC 220.61)
Sizes the feeder/service neutral under NEC 220.61.
Example
You enter
- Maximum unbalanced load (A) 250
You get
- Neutral demand (A) 235
- First 200 a 200
- Excess a 50
Checked against published worked examples from: NEC 2023 (NFPA 70).
Details, formula, and sources
Scopeit carries the maximum unbalanced load, but the portion over 200 A may be taken at 70% (a 250 A unbalanced load -> 200 + 0.70x50 = 235 A). 220.61(C) prohibits the reduction for nonlinear-load portions (electric-discharge lighting, electronic loads), which stay at 100%. A sizing demand, not an operating current; the AHJ and the load classification govern.
Formula or tableordinary: neutral = min(load, 200) + 0.70 x max(load - 200, 0); nonlinear (220.61(C)): neutral = full unbalanced load (no reduction). The first 200 A of unbalanced load at 100%, the portion over 200 A at 70%.
Source and editionFeeder and service neutral load, NEC 2023 220.61(B) (70% on the part over 200 A) and 220.61(C) (nonlinear-load prohibition), by name.
Free accessNEC is free to read at nfpa.org/freeaccess. 220.61(C) prohibits the reduction for nonlinear-load portions (electric-discharge lighting, electronic loads); this tile names that exclusion rather than assuming it away.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namesmax_unbalanced_a, neutral_demand_a, first_200_a, excess_a
- 200 A break the first 200 A of maximum unbalanced load at 100%, the portion over 200 A at 70%NEC 220.61(B)(1)
- Nonlinear exclusion no reduction is permitted for the nonlinear-load portion; that load stays at 100%NEC 220.61(C)