How big a generator for a
1500 sq. ft. house?
Understanding Power Requirements for 1500 sq. ft. homes
Power outages happen at the worst times — during ice storms, hurricanes, summer heat waves, or late on a Friday night when no utility repair crew will be coming until Monday.
If you own a 1,500 square foot home and you're tired of being left in the dark, a whole-home standby generator is one of the smartest investments you can make. But how big does that generator actually need to be?
Let's walk through the math.
What's Running in Your 1,500 Sq Ft Home?
Start With Your Biggest Power Draw:
The Air Conditioner
Every home has a unique electrical load, but we can build a solid estimate around common assumptions. For this exercise, we'll assume your home has:
- A 4-ton central air conditioner (the most power-hungry appliance in most homes)
- Gas heat (so your furnace burners don't draw generator power — but the blower motor does)
- All-electric kitchen appliances — refrigerator, electric range, microwave, and dishwasher
Here's a breakdown of approximate wattage for each major load:
The key figure to understand is starting watts — the surge of electricity an appliance draws when it first kicks on. Your air conditioner compressor demands far more power at startup than it does while running. A generator that can't handle that surge will trip, stall, or fail.
The chart below shows typical starting and running watts for various electrical loads.
Add Up Your Electric Kitchen Appliances
Total Load Estimate for a 1,500 Sq Ft Home
A conservative whole-house load calculation for your setup, here's a conservative estimate of how your peak demand looks:
4-ton AC (running load): ~4,000 watts
Gas furnace blower: ~600 watts
Refrigerator: ~400 watts
Microwave + small appliances: ~1,500 watts
Cooktop - 2 burners running: 3000 watts
Lighting + electronics: ~1,000 watts
Estimated peak total: ~10,500–12,000 watts, with AC startup surge capacity needed above that
That load profile points clearly to a 17kW generator as the best choice for whole-house coverage in a 1,500 square foot home.
Our Recommendation:
Cummins 17kW RS17A QuietConnect
After accounting for running loads and startup surges across all your major systems, a 17-kilowatt generator hits the sweet spot for a 1,500 square foot home with the profile described above.
We recommend the Cummins RS17A 17kW standby generator for whole-house coverage. Here's why it earns our confidence:
- Handles your AC surge. The RS17A delivers enough starting capacity to bring your 4-ton air conditioner online without breaking a sweat — the single biggest challenge for any residential generator.
- Runs your kitchen without compromise. Electric ranges, microwaves, and dishwashers draw significant wattage. The RS17A gives you enough headroom to run multiple appliances simultaneously, the way you actually live.
- Quiet, automatic operation. Cummins engineers the RS17A to start within seconds of a power outage — automatically, without any action from you. Noise levels stay low enough that neighbors won't complain.
- Built to last. The RS17A runs on an all-aluminum, air-cooled engine with a corrosion-resistant enclosure. Cummins backs it with a strong 5-year warranty, and local service and after-hours support from Benchmark Electric offers peace of mind to our customers.
- Fuel flexibility. The RS17A connects to your existing natural gas or LP propane line, so you never store or haul fuel.
For the vast majority of 1,500 square foot homes with gas heat and an electric kitchen, the Cummins RS17A provides reliable whole-house protection with room to spare.
Cummins RS17A Features
Built to withstand anything. The RS17A features a weather-resistant design that withstands 180 mph winds. Straight-line winds and severe storms — the conditions that cause outages in the first place — won't stop the RS17A from doing its job.
Cold-weather reliable. The RS17A operates reliably down to 0°F. When a winter storm knocks out power and temperatures plunge, this generator starts and runs without hesitation.
Intelligent load management. Built-in smart load management automatically controls the operation of up to four high-draw loads, such as your AC, electric range, dryer, and water heater. It staggers startup sequences and balances demand, so the generator never overloads — and you never have to flip a single switch manually.
Rural Home With a Well Pump?
Step Up to the Cummins RS20A
If your home has a private water well, your situation calls for a closer look. Well pumps add a significant electrical draw — typically 900 watts to 2,000 watts running, with starting surges that can spike to 2,000–6,000 watts depending on the pump size and depth.
That added load puts pressure on a 17kW unit, especially when the AC, well pump, and kitchen appliances all want power at the same time.
For rural homeowners with a well pump, we recommend stepping up to the Cummins RS20A 20kW generator. The extra 3 kilowatts of capacity gives you the buffer you need to handle simultaneous high-demand loads without the generator straining or shedding load. You also gain additional headroom for a hot water heater, a chest freezer full of food, or any other appliance you can't afford to lose during a multi-day outage.
The RS20A shares the same reliable Cummins platform as the RS17A — same automatic transfer, same quiet operation, same durable build — just with more muscle when your property demands it.
Get the Right Generator, Right-Sized for Your Home
Choosing the wrong generator size costs you either way — too small, and it fails when you need it most; too large, and you've overspent on capacity you'll never use.
At Benchmark Electric, we size, install, and service standby generators for homeowners across the Mid-South. Our team will assess your exact electrical load, walk you through your options, and make sure your installation meets every code requirement.
Contact Benchmark Electric today to schedule a free generator consultation. When the next outage hits, you'll be glad you did.
Learn more about standby power: