Calculate residential electrical load per NEC 220.83. Check if a home's panel can handle the demand. Learn more
Residential electrical load calculator
Calculate residential electrical load per NEC 220.83. Check if a home's panel can handle the demand.
Property
Standard circuits
Kitchen and laundry
HVAC
NEC only counts the larger of heating or cooling — not both.
Other loads
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How to perform a residential load calculation
An electrical load calculation tells you how much power a home actually draws — and whether the existing panel and service can handle it. This matters when a homeowner wants to add a heat pump, EV charger, hot tub, or workshop. If the load exceeds the panel rating, you are looking at a service upgrade.
This tool follows NEC Article 220.83:
- General lighting and receptacles — Based on square footage (3 VA per sq ft) plus small appliance and laundry circuits.
- Fixed appliances — Water heater, dryer, dishwasher, range, and other permanently installed equipment.
- Heating and cooling — The larger of the heating or cooling load (you do not size for both running at the same time).
- Demand factors — NEC allows reduction factors because not everything runs at full power simultaneously.
The result shows total demand in amps and whether the current service (100A, 200A, etc.) can handle it. If an upgrade is needed, use the service price calculator to price the job with the right margin.
Frequently asked questions
What is NEC 220.83 in residential load calculation?
NEC 220.83 is the National Electrical Code standard for calculating electrical demand in existing homes. It uses demand factors to estimate a realistic power draw, recognizing that not every appliance runs at full capacity at the same time.
When should I perform a load calculation?
Any time you add a major electrical load to a home. Common triggers include EV charger installs, heat pump additions, hot tub hookups, or kitchen remodels. If the calculated total exceeds the panel rating, a service upgrade is required.
How do I calculate the load for a new EV charger?
Most Level 2 EV chargers draw 30-50 amps. Because they run for long periods, they are considered a continuous load. You must include the full nameplate rating of the charger to ensure the home's service can support the additional demand.
Does this tool calculate heating and cooling together?
No. According to NEC standards, a load calculation only includes the larger of the two loads (heating or cooling), since they do not run simultaneously. This calculator handles that automatically to give you the most accurate amperage result.
Why is a precise load calculation important for contractors?
Accuracy prevents the two biggest issues in electrical work: undersizing a service, which leads to tripped mains and fire hazards, or over-quoting a customer for an upgrade they do not actually need. A reliable load calculation builds trust and ensures code compliance.