Dwelling Service Load Calculator (Optional Method)

Inputs

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Living area per the code rules (excludes open porches, garages, unfinished/unadaptable spaces). Drives the 3 VA/ft² general lighting load.
ft²
1,500 VA each; kitchens require a minimum of two.
1,500 VA each.
Sum of NAMEPLATE ratings: range, wall oven/cooktop, dryer, water heater, dishwasher, disposal, microwave, EVSE, well pump, etc. (Use VA = W for resistive; volts × amps otherwise.)
VA
Nameplate of the air conditioner or heat-pump compressor (counted at 100%).
VA
Electric strip heat that can run WITH the compressor (counted at 65% on top of the compressor). Enter 0 if none or if interlocked off during compressor operation.
VA
Total nameplate of electric space heating (baseboards, furnace, cable) when it is the heat source instead of/alongside the options above.
VA
Count of separately controlled space-heating units: fewer than 4 → 65% factor; 4 or more → 40%.
Electric thermal storage or other systems expected at full nameplate continuously (counted at 100%).
VA
Line-to-line service voltage (240 V for the standard US dwelling service).
V

Results

Default result
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Calculated service load(I)
101.3A

Total demand VA ÷ service voltage.

Also computed

Next standard size(I_std)Caution110A

Within 10% of the standard size — future loads (EVSE, heat pump conversion) will likely push past it; consider the next size.

Next standard ampere rating at or above the load (100 A minimum for this method).

Total demand(VA_tot)24,300VA

General demand(VA_gen)17,800VA

First 10 kVA at 100% + remainder at 40%.

Heating/cooling demand(VA_hvac)6,500VA

Governing option: Space heating (fewer than 4 units) at 65%.

Connected general load(VA_conn)29,500VA

General lighting (3 VA/ft²)(VA_ltg)7,500.1VA

Method notes 4 notes
  • Structure of NEC 220.82 (optional method, single-family dwelling served by a 120/240 V, ≥100 A, single-phase service): general + appliance loads at 100% of the first 10 kVA and 40% of the remainder, plus the LARGEST 220.82(C) heating/cooling option. Verify against the adopted code edition and local amendments — this page embeds the rule structure, not the code text.
  • The standard method (220.40 series) and the EVSE/energy-management provisions can give different results; existing-dwelling additions have their own optional method (220.83).
  • Appliance nameplates: enter VA (volts × amps); ranges and dryers use nameplate here — the standard method's Table 220.55 demand factors do NOT apply in the optional method.
  • Heat pumps with interlocked supplemental heat (compressor locked out during strip operation) may omit the compressor from the supplemental option — enter the supplemental as space heating instead in that case.

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