NEC Residential Load Planning Guide
A residential load calculation helps estimate the service size for a dwelling. It collects lighting, receptacle, appliance, cooking, dryer, HVAC, and motor loads in one place. The goal is not guessing. The goal is a defensible electrical load summary.
Why the calculation matters
A home can contain many large loads. They rarely run at full output at the same time. Demand factors help reflect that normal use. They also stop a service from being oversized without review. This calculator follows a worksheet style. It shows each major line, then converts volt-amperes into amperes.
General lighting load
The first step uses floor area. Multiply square feet by three volt-amperes. Then add required small appliance circuits. Add laundry circuits as well. The combined general load uses a demand step. The first three thousand volt-amperes are counted fully. The remaining amount is counted at thirty five percent.
Appliance and equipment loads
Fixed appliances are entered by nameplate value. When four or more qualifying appliances are used, this tool can apply a seventy five percent demand factor. Cooking equipment and dryers have separate fields. The range field uses a simplified single-range demand method. The dryer field uses the larger of nameplate value or five thousand volt-amperes.
Heating and cooling
Heating and air conditioning are normally compared. The larger load is added, unless both can run together. A supplemental heat field is included for systems where added heat may operate with the main equipment. A largest motor allowance is also included, because service calculations often add twenty five percent of the largest motor.
Using the result
The final value is shown in volt-amperes and amperes. The nearest common service size is suggested. Treat that suggestion as a planning value. Always check the adopted code edition, local amendments, equipment labels, and conductor rules before installation. A licensed electrician or authority having jurisdiction should verify final service sizing.
Exporting the worksheet
After calculation, the export buttons save the important rows. The CSV file helps spreadsheet review. The PDF file helps attach a summary to job notes. Keep copies with the panel schedule, equipment cut sheets, and permit documents. Clear records make later changes easier to evaluate and explain during future service upgrades.