Residential load calculation, worked through

The house

2,000 sq ft, two kitchen circuits and one laundry circuit, a 12 kW range, a 5 kW dryer, a 4.5 kW water heater, a 1.2 kW dishwasher, a 0.9 kW disposal, a 1.5 kW built-in microwave, a 5 kVA AC compressor and 10 kW of central electric backup heat.

General load

Lighting 2,000 × 3 = 6,000 VA. Kitchen and laundry circuits 3 × 1,500 = 4,500 VA. Fixed appliances 12,000 + 5,000 + 4,500 + 1,200 + 900 + 1,500 = 25,100 VA. Total general load: 35,600 VA.

First 10,000 VA at 100% = 10,000 VA. Remaining 25,600 VA at 40% = 10,240 VA. General demand: 20,240 VA.

Heating and cooling

AC at 100% is 5,000 VA; central heat at 65% is 6,500 VA. The larger, 6,500 VA, is added. Total: 26,740 VA, or 111 A at 240 V. The next standard size is a 125 A service; most electricians would still install 200 A for future loads.

Adding a 7.2 kW EV charger

The charger adds 7,200 VA to the general load, but only 40% of it counts after the first 10 kVA: 2,880 VA. The new total is 29,620 VA, or 123 A. A 125 A service would be at its limit, a 200 A service has room to spare.