Get matched with top generator install pros in Somerville, NJ

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.

It’s usually better to repair your generator if it isn’t working properly, as it will typically be much more affordable and should yield similar results. Generator repairs cost around $300 on average, while installing a new whole-house generator costs around $5,000 on average. The only exception is if you know your generator is reaching the end of its useful life, usually between 30 and 40 years. If you have an older generator, you could face multiple repairs in the coming years, which might mean that a full replacement will be more cost-effective over time.

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.

No, you should never plug a generator directly into a wall outlet in your house. This practice is extremely dangerous, often illegal, and can cause "back-feeding," where power from the generator flows back into utility lines, creating a life-threatening hazard for utility workers. It can also damage your home's electrical system, including appliances like pumps and HVAC fans. If the main power is restored while the generator is connected, it can destroy the generator and cause an electrical fire. To safely connect a generator, you must use a professionally installed transfer switch or an interlocking kit, which prevents back-feeding by disconnecting your home from the utility grid before the generator provides power.