Determining how many watts to power a house requires more than looking at square footage. A Gilbert home may need only several thousand watts to operate basic necessities during an outage, while a whole-house backup system may require 20,000 watts or more. The right number depends on the appliances, air-conditioning systems, pumps, and other equipment expected to operate at the same time.
Running Watts Vs Starting Watts
Running watts is the electricity an appliance uses during normal operation, but you also have to account for starting watts, the temporary spike required when equipment with a motor or compressor first turns on. A refrigerator may use a relatively modest amount of electricity while running but briefly require substantially more power when its compressor starts. Air conditioners, pool pumps, freezers, and well pumps can create similar surges.
A generator must support your home’s continuous running load while retaining enough capacity for these temporary demands. Adding only the running wattage of each appliance can produce a generator estimate that is too low.
Typical Household Wattage Ranges
Actual wattage varies by the appliance’s size, efficiency, age, and operating mode. You should get a professional load calculation by an experienced electrician to determine how many watts does it take to run a house, but here’s a rough idea of what it takes.
Appliance or System | Running Watts | Starting Watts |
|---|---|---|
Refrigerator or freezer | 500–800 | 1,200–2,000 |
Microwave oven | 1,000–1,500 | Usually similar to running load |
Garage-door opener | 500–900 | 1,000–1,500 |
Television and internet equipment | 150–500 | Minimal additional surge |
Electric water heater | 3,500–5,000 | Usually similar to running load |
Pool pump | 750–2,500 | 1,500–5,000 |
Central air conditioner | 2,000–6,000+ | 5,000–15,000+ |
Electric range or cooktop | 3,000–8,000+ | Usually similar to running load |
Clothes dryer | 4,000–6,000 | Usually similar to running load |
Level 2 EV charger | 7,000–11,500+ | Minimal additional surge |
Generator Wattage Compared With Potential Output
Generator ratings are usually expressed in kilowatts. One kilowatt equals 1,000 watts.
Generator Capacity | Wattage Output | Potential Backup Coverage |
|---|---|---|
8 kW | 8,000 watts | Basic lights, refrigerator, internet, outlets, and selected essentials |
10–14 kW | 10,000–14,000 watts | Essential circuits plus selected larger appliances or limited cooling |
16–20 kW | 16,000–20,000 watts | Broader home coverage, potentially including central air conditioning |
22–24 kW | 22,000–24,000 watts | Many whole-house loads with appropriate energy management |
26–28 kW | 26,000–28,000 watts | Higher-demand homes, large HVAC loads, and broader whole-home coverage |
These are general examples. Your numbers can vary significantly depending on the appliances you need running, fuel type, generator specifications, and which loads may operate simultaneously.
Air Conditioning Can Drive the Calculation
In Gilbert, air conditioning is typically the largest backup load.
Generator sizing should account for your HVAC system’s voltage, amperage, compressor characteristics, efficiency, and startup requirements. Homes with two or more cooling systems require additional planning.
An HVAC system does not necessarily need to run continuously during an outage, but the generator must be capable of starting it safely. Technologies such as soft-start equipment and intelligent energy management may reduce or coordinate startup demands when compatible with the system.
Essential Power Versus Whole-House Backup
When calculating how many watts does it take to run a house, you need to first define what “run” means during an outage.
Essential backup may cover refrigeration, lighting, internet access, security equipment, medical devices, and selected outlets. This approach may require considerably less power than maintaining normal use of every appliance.
Whole-house backup can include air conditioning, cooking equipment, laundry appliances, pool systems, and other large loads.
Newer standby systems increasingly use prioritized circuits and intelligent load management. When generator demand approaches its limit, selected equipment can be delayed temporarily so that higher-priority loads continue operating. An EV charger, electric range, or second air conditioner might therefore be placed behind more critical loads rather than forcing you to purchase a generator capable of running every device at once.
Does Every Home Need 28,000 Watts?
Generac currently lists a 28 kW air-cooled residential standby generator providing 28,000 running watts. its most powerful air-cooled standby model.
That capacity offers a useful upper-end example, but it does not mean every Gilbert home requires 28 kW. A smaller generator may adequately support a home with gas appliances, one air-conditioning system, and carefully selected backup circuits. The answer to how many watts to power a house should come from an evaluation of actual electrical demand rather than the largest available generator rating.
Schedule a Professional Generator Load Assessment
A professional assessment examines the electrical panel, major appliances, HVAC equipment, starting loads, fuel supply, and the homeowner’s outage priorities. It can also identify opportunities to use load management instead of increasing generator capacity.
George Brazil Plumbing & Electrical can calculate your Gilbert home’s backup-power requirements and recommend an appropriately sized Generac system. Rather than relying on an online estimate of how many watts does it take to run a house, schedule an in-home evaluation based on the equipment you actually need during an outage.