How to Choose the Right Generator Size for Your Kansas City Home
Undersizing is the #1 generator mistake. Here's how to calculate what kW rating your KC home actually needs — based on square footage, HVAC, and electrical load.
Generator sizing isn't about square footage alone. It's about electrical load — and getting it right matters.
Why Sizing Matters
An undersized generator will either:
- Fail to start (the load exceeds its capacity and it shuts down)
- Run in constant overload (shortening its life dramatically)
- Force you to choose which circuits to power — defeating the purpose of whole-home backup
An oversized generator wastes money upfront and runs inefficiently. The goal is right-sized.
Quick Sizing Guide
- 7–10kW: Lights, refrigerator, furnace blower, sump pump, a few outlets. No AC.
- 14–16kW: Everything above plus kitchen appliances, laundry, home office. Small window AC maybe — not central.
- 18–22kW: True whole-home including central AC, electric range, and all circuits. This is the most popular choice for Kansas City homes.
- 22kW+: Large homes (3,500+ sq ft), dual HVAC zones, pools, hot tubs, home gyms, or multiple electric appliances running simultaneously.
What Draws the Most Power?
These are the big loads in a typical KC home:
- Central air conditioner: 3,500–5,000W running (15,000–20,000W startup surge)
- Electric range/oven: 3,000–5,000W
- Electric dryer: 4,000–5,500W
- Electric water heater: 4,000–5,000W
- Furnace blower: 500–1,500W
- Sump pump: 800–1,500W (with startup surge)
- Refrigerator: 100–400W running
- Home office (computer, monitor, router): 300–600W
The key is startup surge. Air conditioners and sump pumps draw 3–5x their running wattage when they kick on. Your generator must handle these surges without tripping.
The Load Calculation
A proper load calculation adds up:
- Running wattage of everything you want to power
- The largest startup surge (usually the AC compressor)
- A 20% safety margin
We perform this calculation during every free site assessment. It takes into account your specific HVAC equipment, panel schedule, and which circuits matter most to you.
Kansas City-Specific Considerations
Central AC is non-negotiable for most KC homeowners. Summer outages without AC in 95°F+ heat with Midwest humidity are miserable — and potentially dangerous for elderly residents. If you want AC during outages, you need 18kW minimum.
Sump pumps are critical. Most KC homes have basements, and most basements have sump pumps. Storms that knock out power often bring heavy rain simultaneously. Without a generator, your sump pump stops and your basement floods.
Dual HVAC homes need 22kW+. Many newer homes in Overland Park, Leawood, and Lee's Summit have two HVAC systems (upstairs and downstairs). Running both simultaneously requires a larger generator.
Don't Guess — Get Sized Properly
A free site assessment from Pure Light Electric includes a complete load calculation specific to your home. We'll tell you exactly what size you need — not too small, not oversized.
Call (913) 278-6049 or request a free generator assessment online.
Ready to get started?
Licensed Kansas City electricians — free estimates, no obligation.
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