Get matched with top generator install pros in Columbia, IL

Generators are usually sized by running watts and starting watts. Ideally, you’ll want a generator that can offer both the necessary running watts and starting watts for everything you need to power without going beyond 90% of its capacity. Calculate your home’s electrical load based on the breakers in your home or adding up the appliance and lighting needs of connected rooms.

In most municipalities, you will need a permit to install a permanent home generator, including emergency backup, partial-home, and whole-home generators. A permit for a generator usually costs between $50 and $250, depending on where you live. Your electrician or certified generator installer will usually pull the permit for you—and might be required to do so by your building department—but you’ll be on the hook for the cost of the permit. You should ask your installer before agreeing to any work if they will pull the necessary permits for your project.

To determine the right size generator for your house, you should calculate the total wattage of the appliances and devices you want to power during an outage. List all essential items, note their start-up wattages, and add them together.

Here are some typical wattage requirements for common appliances:

• Refrigerator: 600 watts

• Large dehumidifier: 700 watts

• Large window air conditioner: 1,400 watts

• Water heater: 3,000 to 4,500 watts

• Electric furnace: 5,000 to 25,000 watts

A 7,500-watt generator might be sufficient for essentials like a refrigerator, freezer, well pump, and lighting circuits. However, for high-demand items like a water heater or furnace, a whole-home generator is a better choice. A portable generator may be enough if you only need to power a few critical items.

While home square footage can offer a rough estimate, it is not always a reliable indicator. For reference, here are some typical generator sizes based on square footage:

• 1,000 sq ft: 6–9 kW

• 1,500 sq ft: 7–10 kW

• 2,000 sq ft: 10–14 kW

• 2,500 sq ft: 12–16 kW

• 3,000 sq ft: 16–20 kW+

For the most accurate sizing, consult a professional who can calculate your home's peak and average power consumption and recommend the optimal generator.

While diesel is relatively stable, it won’t last nearly as long as propane and you may have to replace it if it sits unused for too long. Diesel can sometimes struggle to work efficiently or start engines during especially cold weather, so it’s not the best choice for every climate. Compared to fuels like propane and natural gas, diesel generators tend to be noisier and create more exhaust, which isn’t always ideal for home use.