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
Details, formula, and sources
it 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.
ordinary: 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%.
Feeder 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.
NEC 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.
Estimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
Field names used by the API: max_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)