Simple Electrical Service Size Calculation Worksheet

Simplified Service calculation for a one-family dwelling  (based on NEC 220.82)

General load

Add 3 watts per sq. ft. of living area                           __________________

Add 2 Small Appliance circuits at 1,500 watts each   __________________

Add a laundry (washer) circuit at 1,500 watts            __________________

Add the Range in actual nameplate watts                 __________________

Add the water heater in nameplate watts                  __________________

Add dishwasher in nameplate watts                          __________________

Add Dryer in actual nameplate  watts                        __________________

Add all other fixed in place equipment in watts         __________________

                                                Total                           __________________

Add 100% of the first 10,000  watts and 

40% of the remainder  to make SUB-TOTAL             _________________

HEAT LOAD 

Add the largest one of the following 6 choices (in watts)

  1. 100% of A/C load                                          __________________
  2. 100% of Heat pump without electric heat     __________________
  3. 100% of heat pump and 65% Electric heat  __________________
  4. 65% of 1 to 3 space heating units                 __________________
  5. 40% of total of 4 or more electric heaters     __________________
  6. 100% of continuous electric heating units    __________________    

Add SUB-TOTAL                                                      __________________

        HEAT LOAD                                                     __________________

TOTAL WATTS                                                         __________________
Divide TOTAL by 240 to find Amp load of service   ___________________

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