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Neutral Sizing Calculator
NEC 220.61 neutral demand factor calculation — when you can reduce the neutral
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Load Information
240V loads (dryer, range, HVAC, water heater)
120V loads (lighting, receptacles, small appliances)
NEC 220.61 Neutral Sizing
Recommended Neutral Size (75°C Cu)
1 AWG
Full neutral: 125.0A
Neutral Current (full)
125.0A
Demand Neutral Current
125.0A
Neutral % of Total
42.9%
Neutral ≤ 200A — no reduction permitted, full-size neutral required
NEC 220.61 Demand Factor
First 200A @ 100%125.0A
Demand neutral125.0A
NEC 220.61 Reference
220.61(B)Neutral demand: first 200A at 100%, remainder at 70%
220.61(A)Neutral load is the maximum unbalanced demand between ungrounded and grounded conductor
220.61(C)No reduction for nonlinear loads (harmonics) — e.g., electronic ballasts, VFDs, computers
250.24(C)Grounded conductor (neutral) shall not be smaller than required by 250.66 for grounding electrode conductor
⚠ Do NOT reduce neutral on circuits with nonlinear loads (computers, LED drivers, VFDs) — harmonic currents add on the neutral and can exceed phase current.
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