Neutral Load Calculator
Size the feeder or service neutral (grounded) conductor load per NEC 220.61. Enter the line-to-neutral demand loads and the calculator applies the maximum-unbalance basis, the range and dryer 70% reduction, the over-200 A 70% demand factor, and the electric-discharge and nonlinear no-reduction rule, then reports the required neutral load in amperes.
How to use this calculator
- Pick the service or feeder type: single-phase 3-wire 120/240 V, or a 3-phase 4-wire 208Y/120 V or 480Y/277 V wye system. This sets the voltage used to convert the neutral load to amperes for the 200 A test.
- Enter the general line-to-neutral demand: the demand load of the 120 V lighting, small-appliance, laundry, receptacle, and 120 V appliance loads. Leave out straight 240 V line-to-line loads.
- Enter the range/cooking demand (Table 220.55) and dryer demand (Table 220.54). The calculator takes these at 70% for the neutral.
- Enter any electric-discharge or nonlinear neutral load (220.61(C)). It is carried at 100% with no reduction.
- Read the neutral load in amperes. The breakdown shows the reducible neutral, the cooking 70%, the over-200 A reduction, and the non-reducible portion.
NEC reference
This calculator implements NEC 2020 Section 220.61 (Feeder or Service Neutral Load). 220.61(A) sets the neutral load as the maximum unbalanced load between the neutral and any one ungrounded conductor. 220.61(B)(1) permits household ranges, ovens, cooktops, and electric dryers to be taken at 70% of their ungrounded demand. 220.61(B)(2) permits a further 70% demand factor on the portion of the unbalanced load over 200 A for single-phase 3-wire, 3-phase 4-wire wye, and 3-wire DC systems. 220.61(C) prohibits any reduction for electric-discharge lighting and nonlinear loads on a 4-wire wye system. Section 220.61 is unchanged in effect across the 2017, 2020, and 2023 editions, so no edition toggle is offered.
Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.
How the neutral load is built
The neutral only carries the unbalanced load, so the calculation starts from the line-to-neutral demand and applies the 220.61 reductions in order:
| Step | NEC | Treatment |
|---|---|---|
| General 120 V demand | 220.61(A) | Carried at 100% of demand |
| Ranges and dryers | 220.61(B)(1) | 70% of the Table 220.55 / 220.54 demand |
| Unbalance over 200 A | 220.61(B)(2) | Further 70% on the amount above 200 A |
| Discharge / nonlinear | 220.61(C) | 100%, no reduction, added on top |
The 200 A test is in amperes, so the reducible load is converted at the system voltage (240 V for single-phase 3-wire; the square root of 3 times the line voltage for a wye system) before the over-200 A 70% is applied.
Worked example: 200 A dwelling neutral
A single-family dwelling on a 120/240 V, 3-wire service has 15,000 VA of general line-to-neutral demand (lighting, small-appliance, and laundry after the Table 220.42 factors), an 8,000 VA range demand (a 12 kW range, Table 220.55 Column C), and a 5,000 VA dryer demand (Table 220.54). The range and dryer are taken at 70%: (8,000 + 5,000) x 0.70 = 9,100 VA. The reducible neutral is 15,000 + 9,100 = 24,100 VA, which is 24,100 / 240 = 100.4 A. That is under 200 A, so no further reduction applies and the neutral load is 100.4 A. The 240 V water heater and any 240 V straight air conditioner are left out entirely because they carry no neutral current.
Worked example: the over-200 A reduction
A larger service works out to a reducible neutral of 250 A after the range and dryer 70%. NEC 220.61(B)(2) keeps the first 200 A at 100% and takes the remaining 50 A at 70%: 200 + (250 - 200) x 0.70 = 235 A. This is the classic 220.61(B)(2) illustration: only the portion over 200 A is reduced, so the neutral load is 235 A, not the full 250 A. If any of that load were electric-discharge lighting or nonlinear load on a wye system, that portion would be pulled out first and added back at 100%, because 220.61(C) forbids reducing it.
What this tool does not do
- It does not size the neutral conductor. It reports the required neutral load in amperes; pick the AWG or kcmil from Table 310.16 with the Wire Ampacity or Wire Size calculator, applying any ambient or conduit-fill derating.
- The grounded-conductor minimum of NEC 250.24(C) and Table 250.102(C)(1) can govern on a lightly loaded neutral, so the neutral is never smaller than that even when 220.61 gives a lower load. Check it with the Bonding Jumper calculator.
- It does not compute the demand loads themselves. Enter the demand VA from the Residential or Electrical Load, Range Demand, and Dryer Demand calculators.
- Full harmonic / K-factor neutral design beyond the 220.61(C) 100% flag is out of scope.
Frequently asked questions
Do I include the water heater in the neutral load?
No. A 240 V water heater is a straight line-to-line load with no connection to the neutral, so it carries no neutral current and is excluded from NEC 220.61 entirely. The same is true of a 240 V straight air conditioner and a 3-wire (no-neutral) motor. Only line-to-neutral (120 V) loads and the neutral-carrying share of 120/240 V ranges and dryers count.
Is the neutral load the same as the service load?
No. The service (ungrounded) load includes every load, including the 240 V line-to-line loads. The neutral load is only the unbalanced portion and is usually smaller, which is why the neutral conductor is often permitted to be smaller than the ungrounded conductors. Size the ungrounded conductors from the full service load with the Residential Electrical Load Calculator or the Service Size Calculator.
How do I handle the neutral on a 3-phase 4-wire feeder?
Pick the 208Y/120 V or 480Y/277 V system and enter the line-to-neutral demand. The calculator converts to amperes using the square root of 3 times the line voltage. Remember that on a wye system, electric-discharge lighting and nonlinear loads must go in the non-reducible field: 220.61(C) does not allow their neutral to be reduced.
Related calculators
- Range / Cooktop Demand Load Calculator: the Table 220.55 cooking demand to enter in the range field.
- Electric Dryer Demand Load Calculator: the Table 220.54 dryer demand to enter in the dryer field.
- Residential Electrical Load Calculator: the full Article 220 standard method for the general line-to-neutral demand.
- Wire Size Calculator: size the neutral conductor from the required load with ampacity and derating.
Studying for the licensing exam? Our own NEC Code Quickstart works all twelve exam calculations start to finish, each with the code reference. Also in paperback.
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