How to Prepare Your House for a Generator

Written by Jennifer Noonan of
Updated June 21, 2022
There’s a balance to strike between electrical load and generator wattage, and it’s best not figured out on the fly (Photo courtesy of BGE Home and
Photo: shurkin_son / Adobe Stock

There’s a balance to strike between electrical load and generator wattage; it’s best not figured out on the fly

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When we moved to the beach in Southern Delaware, we had lots of “future improvements” in our new-construction building plan. Living close to the coast, a generator made the top of the list. In the wake of Sandy, we’re so grateful we had the forethought. No one wants to show up at the home improvement center just as a hurricane is approaching, having to scramble for one of the 60 generators delivered that afternoon.

If you think you might want to run your house (or a portion of it) on a generator, take some time to do some planning first.

Figure Out Your Load

We worked with an electrician to figure out what we wanted our generator to run. We decided on the sump pump, furnace, hot water heater, kitchen refrigerator and outlets, garage freezer, and the living room lights. A 5,000-watt generator will run all of that for us on about 13 gallons of fuel per 24 hours.

There are many different sizes of portable generators, each with its own powering capacity. Here’s a rough breakdown of common generator sizes and the key appliances they can power during an outage:

  • 1,000 to 2,000 watts: Powers a refrigerator, freezer, coffee maker, a TV, and a couple table lamps

  • 3,000 to 4,000 watts: Powers the above list, plus a couple more appliances, a computer, and some lights

  • 5,000 to 6,000 watts: Powers the above list, plus a window air conditioner, a water pump, and sump pump.

  • 7,000 to 10,000: Powers the above list, plus a hot plate, water heater, and central AC and your furnace for your average-sized home or RV conservatively

*Always consult an electrician to determine the exact load and sizing requirements in your home. Your generator needs may change based on your appliance type, size of your home, and power needs.

Install a Transfer Switch

You can’t just plug a generator into a wall outlet. This process of allowing unfiltered electricity to flow through your circuits at an astronomical rate is called backfeeding, and it is extremely dangerous. Your house needs to be disconnected from the grid before starting a generator. Otherwise, the electricity produced could travel beyond your house, entering the grid and potentially killing utility personnel at work.

The safest way to run a generator is by installing a transfer switch. The switch includes an electrical subpanel with a switch for each circuit you want to run with your generator. The transfer switch is wired directly to the house’s electrical service, and the generator gets plugged into that subpanel. (Our electrician wired an outlet for the generator on our garage exterior.) Throwing that transfer switch completely cuts your house off from the grid; meanwhile, power from the generator is only allowed to go to circuits you’ve designated.

Choose the Right Generator

We don’t live in a secluded area, where services are cut off regularly (or at length). Nor do we have medical equipment that runs 24/7. So we didn’t feel a standby generator was necessary. A backup generator is just fine. Larger systems are obviously more expensive to purchase, install, and run. For us, a 5,000-watt backup generator struck the right balance between what we felt was essential for comfort and what our budget would allow.

Generator needs differ among households. Here are a few things to consider when buying a generator:

  • Number of appliances you want to power: A deep freezer and home-office equipment could up your wattage needs.

  • Whether people in your home use medical equipment: If you need to sustain emergency medical equipment, include the devices in your calculations.

  • Your climate: Areas that endure extreme cold or heat will determine your needs to power an AC or furnace.

  • The size of your home: Simply put, powering more square footage requires higher wattage.

  • Your budget: Portable generator prices range from $600 to $2,500, depending on the size.

Practice Installation

Take some time before disaster strikes to set your generator up and get it running. You should plan to do it a couple of times a year, anyway—to make sure it starts, and so that it is a familiar routine for you. Put the generator outside on a level surface in a well-ventilated area at least ten feet away from the house. Carbon monoxide emitted from fuel can kill, so err on the side of caution. A generator’s engine can get very hot, so keep children and pets far away. Also, put it in a location that’s easy to access for refueling.

If you choose to use a standby generator, you’ll need to budget for installation costs. The cost to install a standby generator averages $4,520, which includes permits, assembly, placement, and wiring. These are permanent units, so they’ll need a concrete pad to sit on, a transfer switch, and fuel purchased from the local gas station to run.

Disasters like Sandy, Irene, and the like have taught us all that we need to be prepared—and that may require more than stocking up on water, canned goods, and batteries a day or two before a storm. With some planning, you can be comfortable knowing that if the power goes out for a day or a week, you’ll be able to sustain the essentials.

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