Choose the loads that matter
Start with the circuits that must work during an outage. Common priorities include refrigeration, lighting, internet equipment, pumps, and selected cooling equipment.
Decide which loads must run at the same time. A selected-load plan may need less capacity than a plan for broader home coverage.
Account for starting loads
Motor-driven equipment can draw extra power for a short time at startup. Air conditioners, refrigerators, and pumps can affect the required capacity.
Generac distinguishes continuous running watts from the extra watts needed to start motor-driven equipment. Generac wattage guide
Ask the installer to calculate running loads and starting loads from equipment data rather than appliance-count estimates.
Review load management and fuel
Load management can keep selected high-demand equipment from starting at the same time.
Fuel type, available fuel capacity, and delivery limits also shape the system design. Ask the installer to assess the electrical and fuel systems together.
Prepare for the sizing visit
List the essential circuits and major equipment. Include cooling systems, pumps, electric water heating, cooking equipment, and medical equipment.
Share photos of equipment labels and the service panel when the installer requests them.
Request a generator sizing assessment
Share the property address, service-panel details, essential loads, fuel type, and expected simultaneous use.
Whole-home generators questions
How do I choose a whole-home generator size?
List the circuits that must run together, then have an installer calculate their running and motor starting loads.
Why do air conditioners affect generator size?
Air conditioners contain motors that can need extra power at startup, so the installer must account for their starting load.
Source: Generac wattage guide
Must a generator power every circuit in the home?
No. A system can cover selected essential circuits or broader home loads, depending on its design and load management.
What information should I provide for a sizing assessment?
Share the service-panel details, essential circuits, cooling equipment, pumps, major appliances, fuel type, and expected simultaneous use.