Electrical Load Calculator

This page applies the dwelling unit load calculation of NEC Article 220 to ratings you supply, by the standard method of Part III or the optional method of 220.82. You enter the floor area, the branch circuit counts and the nameplate of every appliance, and it returns the calculated load in volt-amperes, the current that works out to, and each demand factor it applied with the section it came from. Nothing is assumed from an appliance name, because only a nameplate rating counts. The result is not a service size: the adopted local code and a licensed electrician govern what is installed.

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Floor Area Measured In

The long-hand method. Every appliance rating is taken from its nameplate, and the demand factors of Table 220.42, 220.53, 220.54 and Table 220.55 are applied to them.

Outside dimensions of the dwelling, not counting open porches, garages or unfinished spaces not adaptable for future use, per 220.12. Whole units.
The 20 A kitchen and dining circuits. 210.11(C)(1) requires at least two, and each counts as 1,500 VA.
1,500 VA each under 220.52(B). Enter 0 only where no laundry circuit is required.
One household cooking appliance, in kilowatts off the nameplate. Enter 0 for a gas range. Table 220.55 Note 1 runs to 27 kW.
Off the nameplate. Enter 0 for a gas dryer or none. 220.54 applies a 5,000 VA minimum.
Off the nameplate. Enter 0 if it is gas or if there is none.
Off the nameplate. Enter 0 if there is none.
Off the nameplate. Enter 0 if there is none.
Only a microwave fastened in place. A countertop one on a small-appliance circuit is already counted there.
Add up the nameplates of anything else fastened in place: attic fan, water pump, trash compactor, built-in oven. Ranges, dryers, space heating and air conditioning do not belong here.
The count matters: 220.53 only allows the 75% demand factor when four or more are on the same service.
Total connected electric heat. Enter 0 for gas or oil heat.
The largest air conditioning or cooling load. Enter 0 if there is none.
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Floor Area Measured In

The short method for a one-family dwelling on a single 120/240 V or 208Y/120 V service of 100 A or more. Nameplate ratings are added at 100%, then the first 10 kVA is taken at 100% and the rest at 40%, with heating and cooling handled separately.

Outside dimensions of the dwelling, not counting open porches, garages or unfinished spaces not adaptable for future use, per 220.12. Whole units.
The 20 A kitchen and dining circuits. 210.11(C)(1) requires at least two, and each counts as 1,500 VA.
1,500 VA each under 220.52(B). Enter 0 only where no laundry circuit is required.
The nameplate itself here, not the Table 220.55 figure: 220.82(B)(3) takes the rating of ranges, ovens and cooktops at 100% before the demand factor. Enter 0 for a gas range.
The nameplate. The 5,000 VA minimum of 220.54 belongs to the standard calculation, not to this one.
Off the nameplate. Enter 0 if it is gas or if there is none.
Off the nameplate. Enter 0 if there is none.
Off the nameplate. Enter 0 if there is none.
Only a microwave fastened in place. A countertop one on a small-appliance circuit is already counted there.
Everything else fastened in place or on its own circuit. Heating and air conditioning go in the fields below instead.
The electric space heating nameplate, or the heat pump compressor nameplate where the heating system is a heat pump.
Only for a heat pump with supplemental strip heat. 220.82(C)(3) takes it at 65%.
The largest air conditioning or cooling load. Enter 0 if there is none.
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