Dwelling Load Calculation (CEC Article 220, Part III)
Also known as: standard methodservice load calculationresidential load calcpanel load calculation
The dwelling load calculation is the math that decides whether your existing service can carry a new load — a heat pump, an EV charger, an induction range — or whether the service has to be upgraded first. Article 220, Part III of the California Electrical Code sets out the standard method for running it.
It applies to single-family dwellings. Every load in the house gets counted, but not all of them at full value: the code applies demand factors that account for the fact that a household never runs everything at once. What comes out the other end is a calculated load in amps, which you compare against the rating of the service you actually have.
The calculation: 1. General lighting and receptacles: habitable sq ft × 3 VA, plus 2 small-appliance circuits × 1,500 VA and 1 laundry circuit × 1,500 VA. Of that pool, the first 3,000 VA counts in full and the rest at 35%. 2. Appliances fastened in place: nameplate VA for each — dishwasher, disposal, microwave, water heater, well pump. At four or more of them, the group counts at 75%. 3. Dryer: 5,000 VA or nameplate, whichever is greater. 4. Range: from the range table — 8,000 VA for a single range up to 12 kW. 5. Heating or cooling, never both: the larger of the two. Fixed electric heat counts in full. 6. EV charging: the greater of 7,200 VA or the charger nameplate, at 100%, outside every demand factor above. 7. Largest motor: add 25% of it back. 8. Convert to amps: total VA ÷ 240V, then compare to the service rating.
Most homeowners hear "your panel is too small for an EV charger" or "you need a 200A upgrade" and have no way to check the claim. This calculation is what that answer actually rests on. Our Panel Load Calculator runs it so you can see the number for your own house — whether that turns out to be "you need the upgrade" or "you're fine, just add the circuit."
Panel upgrade pressure is real in this industry, and a 200A upgrade is real money. We run the calculation and recommend the upgrade when the math says so, not before. If your 100A panel carries the EV charger, we install just the circuit. It is not our house method either — the County of Santa Cruz sets out these same steps on the load-calculation worksheet it asks for with a permit application, so you can check our arithmetic against the form.
Met this term in a quote or inspection report?
A free whole-home inspection turns jargon into a written assessment of your actual house — you keep the report either way.