How big a generator for a
3000 sq. ft. home?
Understanding Power Requirements for 3000 sq. ft. homes
Power outages are unpredictable — and for homeowners, they're more than just an inconvenience. When you've got a 3,000 square foot home with two air conditioners, gas heat, and a fully electric kitchen, the wrong generator leaves you sweating through a summer outage or watching your appliances sit cold. The right generator keeps life running exactly as it should.
At Benchmark Electric, we help homeowners cut through the confusion and size a generator that fits their needs. For illustration purposes, here are a few basic assumptions for this 3000 square foot home:
- Two central A/C units - a 4-ton and 3-ton A/C
- gas heat, and
- all electric kitchen
For homes fitting this profile, we typically recommend one of two solutions depending on your budget and backup power goals.
Understanding Your Home's Power Demands
Before sizing a generator, it helps to understand what your home is drawing.
A 4-ton central air conditioner requires roughly 8kW on startup and 4kW to run — often the single largest load in the house. Add a 3-ton A/C, and you've got two large loads competing for power simultaneously. Layer in an electric oven, an electric clothes dryer, a refrigerator, lighting, and miscellaneous outlets, and a 3,000 sq ft home can easily demand 25–35+ kilowatts during peak use.
That's where the choice of generator — and how intelligently it manages those loads — becomes critical. Here are the two options we recommend for homes with this profile.
Option 1: Managed Whole House — Cummins RS20A QuietConnect
Smart Power Management at a Cost-Effective Price Point
The Cummins RS20A is a 20kW air-cooled standby generator built specifically for whole-home backup with intelligent load management.
Rather than attempting to power everything at once — which would require a much larger, more expensive unit — the RS20A uses integrated load management to cycle managed loads in and out based on available power capacity.
For this home, the load management is configured as follows:
- The 4-ton A/C is prioritized — it runs whenever the generator can support it and takes precedence over all managed loads.
- The 3-ton A/C is a managed load — it runs when capacity allows and steps aside when the larger A/C needs power.
- The kitchen oven is a managed load — it can be shed temporarily when demand peaks.
- The clothes dryer is a managed load — shed during heavy power draws, restored when capacity is available.
The result is a home that stays comfortable and functional during outages without the cost of stepping up to a larger generator.
You may not be able to run the oven and both A/C units at the exact same moment, but the system manages the loads automatically — and most homeowners never notice the difference.
Distinguishing Features of the RS20A:
- Cold weather ready out of the box — performs reliably down to 0°F without any modifications or add-ons.
- Certified to EPA, UL, and CSA standards — ensuring safety, environmental compliance, and insurance compatibility.
- NFPA 37 compliant — allows installation as close as 18 inches from your home, a meaningful advantage on smaller lots where setback space is limited.
- Just 65 dB(A) at full load - you and your neighbors will hardly notice it running.
For homeowners who want whole-house coverage without the whole-house price tag, the RS20A is a compelling solution.
Option 2: True Whole House Coverage — Cummins RS30 QuietConnect
Maximum Capacity for Uncompromising Backup Power
If you want every appliance, every circuit, and every load running on demand — just like when operating under utility power — the Cummins RS30 is the answer. At 30 kilowatts, this liquid-cooled powerhouse is engineered for homeowners who won't compromise on comfort or convenience during an extended outage.
The RS30 is built around a 2.4L 4-cylinder liquid-cooled engine. Unlike air-cooled engines, liquid cooled engines enable longer continuous run times and more stable performance under sustained heavy loads — exactly what a 3,000 sq ft home demands when both A/C units, the oven, and the dryer are running at once.
The RS30's standout features include:
- Extreme cold weather starts down to -40°F
- Certified to EPA, UL, and IBC Seismic standards
- Aluminum enclosure with durable powder coat paint — the best-in-class anti-corrosion protection for high-humidity environments like Memphis.
- Enclosure evaluated to withstand 180 mph wind loads — built tough enough for straight-line winds and severe storms where backup power matters most.
- Quiet operation: just 60 dB(A) at full load - that's 5 decibels quieter than the RS20A's quiet performance.
The Cummins RS30 QuietConnect is the right choice if you've experienced extended outages lasting days or weeks, or if you simply want the peace of mind of knowing your generator can handle everything your home throws at it — no compromises, no shedding, no scheduling.
Which Option Is Right for You?
Both generators are excellent solutions — the right choice comes down to your priorities.
If cost-effectiveness is the primary driver and you're comfortable with smart load management handling peak demand, the RS20A delivers impressive managed whole-home coverage at a more accessible price point.
If you want maximum capacity, extreme durability, and the ability to run your entire home indefinitely without restriction, the RS30 is worth every dollar.
Either way, both units are automatic standby generators — meaning they monitor utility power 24/7 and kick on within seconds of an outage, without any action required from you. By the time you notice the lights flicker, your generator is already running.
Let Benchmark Electric
Size It Right
Generator sizing isn't one-size-fits-all solution and getting it wrong is an expensive mistake in either direction. Undersized and you're shedding critical loads at the wrong moment. Oversized and you've spent thousands more than necessary.
Not all 3000 square foot homes are alike; air-conditioning needs, electric heat, kitchen appliances, sump and pool pumps, and private water wells in rural areas will add to the mix and influence our final recommendation.
It is advisable to consult a qualified generator specialist to ensure appropriate sizing for your generator.
At Benchmark Electric, our team handles the full process — load calculation, equipment selection, installation, and ongoing service and support. We're a certified Cummins dealer with over 20 years of experience installing and sizing home generators.
Contact us today for a free consultation. Let's make sure your home is ready for whatever Mother Nature brings.
Learn more about standby power: