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NEC Art.220
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How it works
Enter your values
Type in your inputs — the app fills code tables and constants for you, so there's nothing to look up.
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Instant answer with a clear PASS / FAIL and the exact NEC Art.220 reference behind every number.
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What this calculator does
A dwelling load calculation tells you how big a service or feeder a home needs by adding up its electrical loads and applying the demand factors the NEC allows. Get it wrong and you either oversize the service and waste money, or undersize it and fail inspection. This app runs the popular NEC 220.82 Optional Method (Section 120.82 in the relocated NEC 2026 Article 120) and shows every line so you can hand the result to an inspector.
The NEC 220.82 optional method
For a single dwelling the optional method is faster than the standard method and usually yields a smaller, legal service. It works in three parts:
- General loads — 3 VA per ft² of living area, plus 1500 VA for each of the two required small-appliance circuits and the laundry circuit, plus the nameplate rating of every fixed appliance (water heater, dishwasher, disposal, dryer, range, and so on).
- Demand factor (220.82(B)) — take the first 10 kVA of that total at 100% and everything above 10 kVA at 40%.
- Heating or cooling (220.82(C)) — add the larger of the two, never both: air-conditioning at 100%, a heat pump compressor at 100% plus its supplemental heat at 65%, or electric space heating at 65% (fewer than four separately controlled units) or 40% (four or more).
Worked example — 2,000 ft² home
General lighting: 2,000 ft² x 3 VA = 6,000 VA. Small-appliance and laundry: 3 x 1,500 = 4,500 VA.
Appliances: water heater 4,500 + dishwasher 1,200 + disposal 900 + dryer 5,000 + range 12,000 = 23,600 VA.
Sum of general loads = 6,000 + 4,500 + 23,600 = 34,100 VA. Apply 220.82(B): first 10,000 at 100% = 10,000, remaining 24,100 at 40% = 9,640. Subtotal = 19,640 VA.
Heating vs cooling per 220.82(C): a 10 kW electric furnace counts at 65% = 6,500 VA, which beats the 5,000 VA A/C. Total = 19,640 + 6,500 = 26,140 VA / 240 V = 108.9 A → a 125 A service.
The app applies these 220.82(C) selections for you — heat pump compressors at 100%, supplemental strip heat at 65%, electric space heating at 65% or 40% by unit count — and lets you toggle between NEC 2023 and NEC 2026 to see how the updated demand factors change the result.
Related calculators
Once you have the service size, pick the feeder with the wire size calculator and protect it with the breaker size calculator.
Electrical load FAQ
Which method does the calculator use?
The NEC 220.82 Optional Method for single dwellings: first 10 kVA of general loads at 100% and the remainder at 40%, plus the 220.82(C) heating/cooling selection. In the NEC 2026 edition the same method lives in Section 120.82 with an 8 kVA first tier, and the app supports both editions.
What loads have to be included?
General lighting at 3 VA per square foot, the two small-appliance circuits and the laundry circuit at 1,500 VA each, and the nameplate rating of every fixed appliance such as the water heater, dishwasher, disposal, dryer, and range.
How is the service size in amps found?
Divide the calculated demand in VA by the service voltage (240 V for a standard residential service), then round up to the next standard service size such as 100, 125, 150, or 200 amps.
Does it support NEC 2023 and 2026?
Yes. You can switch between the 2023 and 2026 editions instantly to see how the updated demand factors affect the result, and every line shows the article it comes from.
Does it work offline?
Yes, the calculator runs 100% offline with no account. Free with rewarded ads; a one-time $2.99 Pro unlock adds PDF export and saved history.
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