A standby generator is only useful if it's powerful enough to run what you need. Too small, and it'll overload and shut down. Too large, and you've overspent. Here's how to size a generator for a Phoenix home.
Calculate Your Critical Loads
Start with the appliances you absolutely need during an outage. In Phoenix, air conditioning is non-negotiable — summer power outages without AC become dangerous fast.
- Central AC (3-5 ton): 3,500-6,000 watts running, 7,000-12,000 starting
- Refrigerator: 400-800 watts
- Well pump (if applicable): 1,000-2,000 watts
- Pool pump: 1,500-2,500 watts
- Garage door opener: 500-1,000 watts starting
- Lights and outlets: 1,000-2,000 watts
- Medical equipment: varies
Whole-Home vs. Essential Circuits
A whole-home generator powers everything. An essential-circuit setup powers only your critical loads. For Phoenix homes, we generally recommend whole-home coverage (22-24kW) because Arizona's summer heat makes AC a health necessity, not a comfort item.
Natural Gas vs. Propane
Most Phoenix homes have natural gas, which means your generator runs on the same supply — no refueling, no tanks to maintain. Homes without natural gas use propane, which requires a tank installation.
Our Recommendation
For most Phoenix homes with a 3-5 ton AC unit and typical loads, a 22kW Generac Guardian provides whole-home coverage with headroom. We'll do a load calculation specific to your home before recommending a size.