NEC Article 220 lets you reduce a building’s raw connected load to a realistic demand load because not every appliance runs at full power at once. This calculator walks through the 220.42 general lighting factor, the 220.52 small-appliance and laundry additions, the 220.54 dryer factor, and the 220.55 Column C range table to produce a feeder or service demand load for permit submissions.
How it works
Each load category gets its own demand treatment, then they are summed:
general connected = general lighting VA + (small-appliance + laundry circuits) × 1500
general demand = first 3000 VA × 100% + 3001–120000 × 35% + above 120000 × 25%
dryer demand = max(nameplate, 5000) × count × table 220.54 factor
range demand = Table 220.55 Column C kW for the range count
total demand = general demand + dryer demand + range demandThe general lighting factor does most of the work: above the first 3000 VA only 35% of the load counts, which can roughly halve a large dwelling’s calculated lighting load.
Worked example
A 1500 sq ft dwelling has 1500 × 3 = 4500 VA general lighting load (3 VA per
square foot per 220.12). Adding two small-appliance circuits and one laundry
circuit brings the connected general load to 4500 + 3 × 1500 = 9000 VA. The
220.42 demand factor gives 3000 + (9000 − 3000) × 0.35 = 5100 VA demand.
One 5000 VA dryer at 100% and one range at 8 kW under Table 220.55 Column C
push the total to about 5100 + 5000 + 8000 = 18,100 VA.
At 240 V, that is roughly 75 A — well within the capacity of a 100 A service for this particular load mix. Add heating, cooling, EV, and motor loads separately.
Load types not covered by these demand factors
These four demand factors handle the basic residential core. Additional loads are calculated separately and added to the total:
- Heating and air conditioning: Use 100% of the larger of heating or cooling load per 220.60 (non-coincident loads), or the actual connected load if both can run simultaneously.
- Electric vehicle chargers: EAS (EV supply equipment) gets its own demand factor under the adopted code edition, or is counted at nameplate for a conservative calculation.
- Fixed motor loads: Motor loads are generally calculated at 125% of the largest motor’s full-load current plus 100% of others.
- Water heaters, pool pumps, and other continuous loads: Continuous loads are counted at 125% of nameplate for branch circuit sizing, though feeder demand calculations sometimes treat them differently.
Standard vs optional calculation method
This calculator uses the standard method from NEC Article 220, which applies individual demand factors by load category. The optional method in 220.82 uses a single combined demand factor for dwellings and is often simpler to apply for a standard house. Some jurisdictions or plan reviewers prefer one over the other — verify which your AHJ accepts before submitting a permit.
The standard method gives a more granular result and is generally required for non-dwelling or complex dwelling loads.
Common mistakes
- Adding small-appliance and laundry circuits after the 220.42 factor instead of before — they must be combined with general lighting first.
- Using Column B or Column A of Table 220.55 for ranges over 12 kW, when Column C applies only to ranges rated 12 kW or less.
- Forgetting that heating and cooling loads do not receive any of the demand factors listed here — they are a separate addition.
Add heating, cooling, EV, and motor loads separately, since they are not part of these particular demand factors.