--- title: What Size Generator Do You Really Need for an Arizona Home — With Actual Load Numbers description: Wondering [av_keyword_plain]? We break down real load numbers for [sa_city] homes so you buy the right generator — not too small, not overkill. url: https://fhrelectric.com/what-size-generator-do-you-really-need-for-an-arizona-home-with-actual-load-numbers date_modified: 2026-07-12 author: language: en_US --- Summer monsoon knocks out the grid near Fountain Hills. Your AC stops. The refrigerator starts warming. If you have a home office, a Tesla on the charger, or medical equipment running, that outage stops being an inconvenience and starts being a genuine crisis. The real question — — has a real, calculable answer, and we’re going to walk through it with actual watt numbers so you stop guessing and start planning. Chris here, and we’ve sized enough generators across , Chandler, Mesa, and North Scottsdale to know that most homeowners are either dramatically undersized or paying for capacity they’ll never use. ## Why Matters More in Arizona heat is not ambient background noise — a 115°F afternoon turns your home into a liability within two hours of power loss. That changes the math. In cooler climates, you can sometimes limp through an outage with a small portable unit. Here in , your central AC is non-negotiable, and that single appliance can swing your generator requirement by 10,000 watts or more depending on tonnage. Before you start shopping, you need a realistic load list — not a vague estimate. ## Real Load Numbers for a Typical Home ![Licensed electrician completing a what size generator do I need for my house assessment during a standby generator installation at a modern Arizona home](https://fhrelectric.com/wp-content/uploads/2026/07/avathan-6a53cad3029bb.jpg "What Size Generator Do You Really Need for an Arizona Home — With Actual Load Numbers") Here’s how the numbers actually stack up. These are running watt figures — starting (surge) watts run 1.5–2× higher for motors, so keep that in mind for anything with a compressor: - **Central AC (3-ton):** ~3,500–4,500 running watts; surge up to 9,000 W - **Central AC (5-ton, common in larger Scottsdale homes):** ~5,500–7,000 running watts - **Refrigerator:** ~150–400 running watts; surge up to 1,200 W - **Sump pump or pool pump:** ~750–1,500 running watts - **Lighting (LED throughout):** ~500–1,000 W total - **Home office (two monitors, router, NAS):** ~300–600 W - **Level 2 EV charger (if you want it on backup):** ~7,200 W at full draw - **Electric range / oven:** ~2,000–5,000 W - **Medical equipment (CPAP, O2 concentrator):** ~150–600 W A modest 2,200 sq ft home in Gilbert running a 3-ton AC, a refrigerator, lights, and a home office lands right around 6,000–7,500 running watts. A larger home near Old Town Scottsdale with a 5-ton system, pool pump, and home office pushes past 12,000 running watts easily. Add an EV charger and you’re looking at 18,000–20,000 W. > The number one generator sizing mistake we see in : people size for average load, then wonder why the unit shuts down the moment the AC compressor kicks on. Always size for surge, not just running watts. ## Whole House Generator Size: Practical Tiers ![Licensed electrician completing a what size generator do I need for my house assessment during a standby generator installation at a modern Arizona home](https://fhrelectric.com/wp-content/uploads/2026/07/avathan-6a53cadec4c82.jpg "What Size Generator Do You Really Need for an Arizona Home — With Actual Load Numbers") Using a [whole-home generator backup](https://fhrelectric.com/services/backup-power-generators/whole-home-generator-backup-power/) approach means your automatic transfer switch handles the switch-over — no extension cords, no manual startup at 2 a.m. Here’s how the standard generator size tiers map to real homes: - **10–14 kW:** Covers essential circuits only — AC (smaller unit), fridge, lights, outlets. Good for a 1,200–1,800 sq ft home with no EV charger. Budget range: roughly $4,000–$7,000 installed. - **16–20 kW:** The sweet spot for most mid-size homes. Handles a 3–4 ton AC, full lighting, kitchen essentials, and a home office. Budget range: roughly $6,500–$10,000 installed. - **22–26 kW:** Larger homes, 5-ton systems, pool pumps. This is where most North Scottsdale and Fountain Hills builds land. Budget range: roughly $9,000–$14,000 installed. - **30–36 kW+:** If you want EV charging on backup, a large home with multiple HVAC zones, or a home-based dental or medical office — this tier keeps everything running without load-shedding. Budget range: $13,000–$20,000+ installed. These are real-world installed ranges for , including transfer switch, gas line extension, and permits. They will vary with panel condition, natural gas pressure at the meter, and site-specific factors — which is exactly why a proper load assessment matters before you commit to a unit. Our [home electrical load assessment](https://fhrelectric.com/what-a-home-electrical-load-assessment-actually-involves-and-why-you-need-one-before/) process gives you hard numbers before a dollar is spent on equipment. If your panel is aging — say, 20–30 years old, common in Gilbert and Tempe builds from the late 1990s — a generator installation is a natural time to evaluate it. We’ve written about [panel health checks every Arizona home should have](https://fhrelectric.com/what-is-a-panel-health-check-and-why-every-arizona-home-should-have-one/), and it’s worth reading before you finalize a backup power budget. ## EV Owners and Generator Sizing: The Detail Most People Miss If you’ve got a Tesla or another EV in the garage — and in , a large number of our clients do — be honest with yourself about whether you want charging capability during an outage. A Level 2 charger pulls 30–50 amps at 240V. That’s a meaningful chunk of generator capacity. You have two options: include it in the sizing calculation and go to a 30 kW+ unit, or add a load-management device that deprioritizes the charger when other loads spike. We do both, and we can walk you through [Tesla charger installation](https://fhrelectric.com/services/ev-chargers-smart-home-low-voltage/tesla-charger-installation-services/) that integrates cleanly with a standby system. For business owners — a restaurant on Scottsdale Road, a dental office near the 101 — the stakes are even clearer. A mid-service power loss isn’t just inconvenient, it’s a liability. Our [standby generator installation and maintenance](https://fhrelectric.com/services/backup-power-generators/standby-generator-installation-maintenance/) service is built around that kind of zero-downtime requirement. [Get a Free Generator Sizing Estimate — Call](tel:(602) 492-9999) We’re , and we’ve been doing this across Maricopa County for over 20 years — licensed, insured, and ready to give you a straight number before a single piece of equipment moves. Call and let’s figure out exactly what your home needs.