Start with what you want to keep running
The right generator size depends less on square footage than on which electrical loads you expect to use during an outage. One household may only need refrigeration, heating controls, a sump pump and a few lights. Another may want central air conditioning, an electric range, well pumps and other large appliances available at the same time. Both homes can be similar in size and have very different generator requirements.
Essential-circuit backup versus whole-home backup
With essential-circuit backup, selected circuits are prioritized so the home can maintain key functions during an outage. Whole-home backup is designed to support a broader set of loads, but “whole home” does not necessarily mean every high-demand appliance can operate simultaneously without controls. It is important to define expectations before choosing equipment.
Why the largest appliance matters
Electric heating, air conditioners, electric water heaters, ranges, dryers, well pumps and EV charging can all affect the sizing discussion. Motors may draw extra current when starting. Your electrician should consider both continuous operating demand and the starting requirements of equipment that may turn on automatically.
How load management can help
Some installations use load-management equipment to temporarily prevent or defer selected large loads while the generator is running. This can make a smaller generator practical for some homes. It is not a universal solution: the selected equipment, controls and homeowner expectations need to be reviewed together.
What about natural gas and propane?
Fuel availability matters. The generator’s rated output can differ by fuel type, and the fuel system must be able to deliver the required supply under expected conditions. Gas piping, regulators, meter capacity or propane tank arrangements should be evaluated by the appropriate licensed trades. Do not assume the existing gas line can support a generator.
How an installer determines the size
A proper consultation considers the home’s electrical service, the specific loads to be supported, equipment specifications, starting current, fuel availability, transfer equipment and installation location. We also discuss whether you expect to add a heat pump, EV charger or other major electrical load in the future. The result is a recommendation based on your home rather than a generic chart.
Installation details that affect the project
Generator placement must account for manufacturer instructions, exhaust clearance, access for maintenance, local requirements and safe transfer of power. A permanently installed standby generator also needs appropriate transfer equipment to prevent dangerous backfeeding. A quote should clearly state what electrical and gas work is included and what may require separate coordination.
Frequently asked questions
Is a 22 kW generator enough for my house?
It may be, but the answer depends on your actual loads, starting demands and any load-management strategy.
Can a generator run an EV charger?
Potentially, but EV charging is a significant load and is often managed or excluded during outages.
Does a bigger generator always mean better backup?
No. Correct sizing, fuel supply, installation quality and maintenance are more important than buying the largest unit available.
Ready to talk to an electrician?
Considering a Generac standby generator? Ask GEM Electrical Services for a home-specific backup power consultation in Brantford and surrounding communities.
