Backup-power load planning

Size the load—not the house.

Select what must run during an outage. Edit every wattage using the actual equipment labels, then account for the largest motor-starting surge.

Choose your loads

Custom equipment name

Running wattsStarting watts

*Central A/C values vary enormously. Use the nameplate, product literature, or a qualified load calculation. Sample numbers are placeholders, not specifications.

Estimated requirement

Suggested generator class

3 kW

Selected running load1,200 W

Largest added surge1,500 W

Minimum calculated load2,700 W

Suggestion includes approximately 20% headroom and rounds up to a common generator size. Verify voltage, amperage, fuel supply, transfer equipment, and load-management requirements.

Why starting watts matter

Motors in refrigerators, pumps, blowers, and air conditioners briefly demand more power while starting. The planning method adds all selected running loads, then adds the largest single extra starting surge because equipment can be sequenced instead of starting every motor simultaneously.

Don’t size from square footage alone. Two similar houses can have completely different electrical loads. Heating type, water heating, well equipment, air conditioning, EV charging, and load management change the answer.

Before purchasing

This is an initial planning estimate. Have a licensed electrician or qualified generator dealer verify the load, service configuration, conductor sizing, overcurrent protection, transfer method, and applicable code requirements.

Sizing approach: selected running watts + largest additional starting surge, then planning headroom. Confirm actual nameplate and manufacturer data.