How do you calculate what size generator a house needs?
An electrician lists the appliances you want powered, adds their running loads, and then accounts for the extra surge when motors start, especially the AC compressor. The result is compared with your service size to choose a generator that covers the load without being far oversized.
The air conditioner is usually the deciding load in Arizona. A large compressor draws far more at startup than it does once running, and that surge sets the minimum generator size. Soft start devices can reduce the surge and sometimes allow a smaller unit.
Many homeowners start by saying whole house and end up choosing essential circuits instead. Both are valid. The list of what you must keep running through a summer outage is the most useful starting point for the calculation.
Is a whole house generator better than a portable one?
A standby whole house generator starts automatically, runs on natural gas or propane, and powers the house through a transfer switch. A portable generator needs manual setup, fueling and extension cords or a safe inlet connection, and it usually cannot run an entire house.
Never run a portable generator inside a house or garage, or near windows and doors. Carbon monoxide is deadly and builds up fast. Never backfeed a house through a dryer outlet or any improvised connection, which is dangerous to you and to utility workers.
A transfer switch keeps generator power from flowing back onto utility lines, which protects line workers, and it lets the house switch over cleanly. It is required for a safe permanent connection and is installed by a licensed electrician.
What is a load management device for a generator?
A load management device cycles large appliances, such as the AC and the dryer, so they do not all run at once. This lets a smaller generator serve a bigger house. It trades some convenience for a lower equipment size and is installed along with the transfer switch.
It is useful when the main appliance load is high but not constant. You may notice the dryer waits while the AC runs, or the water heater pauses. For many families that is a fair trade during an outage.
Your electrician can show which circuits are managed and explain the trade-offs before you commit. Ask how priorities are set, so the AC or other critical loads are not the ones that get cut off first.
Does my panel affect what generator I can install?
Yes, the electrical service size and the condition of the panel affect which generator and transfer switch you can use. Older panels in places like Sun City and Sun City West may need updates before a whole house connection is safe, so an inspection comes first.
The transfer switch must match the service rating, and the panel needs room and sound parts to accept it. A panel with no space or damaged components complicates matters, and sometimes a panel upgrade is the right first step.
Permits and inspections are normal for permanent generators. Placement rules, such as distance from windows, and the gas supply also need to be checked, and your installer should walk you through them before any work starts.
More questions: Home Generators: 12 Most Asked Questions Answered