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Panel and Service Size Estimator

Connected-load demand estimate for a residential service, with the service amps and the next standard size.

Inputs

Connected load

Total general lighting and receptacle load, commonly 3 VA per square foot or the NEC minimum.

Nameplate VA of fixed appliances: water heater, range, dryer, dishwasher, disposal.

The larger of heating and cooling, not both, in most residential calculations.

Result

Estimated demand
13.55 kW
Estimated demand
13,550 VA
Lighting demand after the first 3,000 VA
4,050 VA
Next 25 A increment (verify standard sizes)
75 A
Calculated service current at 240 V
56.5 A
With 25% headroom
70.6 A

What to check

  • Connected load totals by category, using nameplate VA for fixed appliances and the NEC minimum for general lighting.
  • The NEC optional method (220.82) rather than the standard method modeled here, if your AHJ accepts it for the dwelling.
  • Largest HVAC load only, not heating and cooling added together, unless both can run at once.
  • EV charging, which is often the deciding factor and may need load management instead of a larger service.

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Standard-method style demand estimate (NEC 220.42 lighting demand plus connected fixed loads). The NEC optional method, EV load management, and local amendments change the result materially. Service size, conductors, and overcurrent protection are a design task that the AHJ and a licensed electrician must approve.

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