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Home Electrical Service Calculation

Summary: The home electrical service size is based upon the electrical loads and the required circuits specified by the electrical codes as shown in this example.

Electrical Service Calculations Process

This electric service calculation is based on a single family home of 3000 square foot with the following electrical loads:

1- 12 kw electric range

20 kw of electric space heating (1 central elect. heating unit)

1- 5 kw electric water heater

1-central air conditioner, 9 kw

1- dishwasher, 1 kw

1- disposal, 0.9 kw

1- electric clothes dryer, 4500 watt

NEC Electric Service Calculation - Home 3000 sq. ft.

NEC Ref. Load VA
220-3a General Lighting, 3000 sq ft x 3 watts = 9000 --
220-16a 2 Small Appliance, 1500 ea= 3000 --
220-16b Laundry = 1500 --
Table 220-11 Total General Lighting, Small Appl., Laundry = 13500 --
Table 220-11 Apply Demands, 1st 3000 watts 3000
Table 220-11 Balance(10500 watts) at 35 percent 3675
220-18 Dryer (minimum 5k) 5000
220-19 Range (from col C) 8000
220-17 Add Fixed Appliance x 100 percent (not more than four) 6900
220-21 Larger of Heat / Air Conditioning 20000
VA Total 46575
Amps Divide by 240 (volts) = 194
310-15(b)6 200 Amp service wire: 2/0 copper


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