The size of the generator you need to back up your house depends on the total wattage required to run essential appliances and systems during a power outage. Here’s a step-by-step guide to help you determine the right generator size:
List Essential Appliances and Systems
Identify which appliances and systems you want to keep running during a power outage. This might include:
- Refrigerator and freezer
- Lights
- HVAC system (heating and cooling)
- Water heater
- Sump pump
- Kitchen appliances (like microwave or oven)
- Electronics (like TVs, computers, etc.)
- Medical devices (if necessary)
Calculate the Total Wattage
Find the Starting and Running Wattage: Each appliance has a starting (surge) wattage and a running wattage. The starting wattage is higher and only needed for a few seconds when the appliance first turns on.
Add Up the Wattages: Add together the starting wattages of the highest-drawing appliances and the running wattages of everything else you want to power simultaneously.
Here are some approximate wattages for common appliances:
- Refrigerator: 600-800 running watts, 1200-2000 starting watts
- Central air conditioner: 2000-4000 running watts, 5000-8000 starting watts
- Electric water heater: 4500 watts
- Sump pump: 750-1500 running watts, 1500-3000 starting watts
- Lights: 60-300 watts (depending on the number of lights)
- Microwave: 800-1200 watts
Choose a Generator Size
Small Generators (3,000-5,000 watts): Suitable for powering essential appliances like a refrigerator, lights, and a few small devices.Medium Generators (5,000-7,500 watts): Can power essential appliances and some additional items like a sump pump and a window air conditioner.Large Generators (7,500-10,000 watts): Can handle most household needs, including larger appliances and possibly a central air conditioner.Whole-House Generators (10,000+ watts): Can power your entire home, including central heating and cooling systems, well pumps, and more
Consider Future Needs
If you plan to add more appliances or systems in the future, it’s a good idea to choose a generator with a slightly higher capacity to accommodate additional load.
Consult a Professional
It’s always a good idea to consult with an electrician or generator specialist to ensure you choose the right size generator for your specific needs and to safely install the generator.
Additional Considerations
Fuel Type: Generators can run on gasoline, propane, natural gas, or diesel. Consider the availability of fuel in your area.Transfer Switch: Installing a transfer switch is essential for safely connecting your generator to your home’s electrical system.
