Generator Transfer Switch Cost

A transfer switch connects a generator to your home's wiring safely, so power cannot feed back into utility lines. HomeGuide puts transfer switch installation at $400 to $2,500; Angi lists about $1,200.

Cost by setup

With a standby generator

HomeGuide puts a complete standby generator at $6,000 to $11,000 installed. Permits run $80 to $450 (HomeGuide) or $50 to $200 (Angi). See whole house generator cost.

Panel capacity

For panel prices, see electrical panel upgrade cost.

Generator installation parts (HomeGuide)

Angi's installation figures

Angi lists a transfer switch at about $1,200, an electrical subpanel upgrade at $500 to $2,000 and new circuit installation at $570 to $1,000. It puts standby generator installation, including permits, placement and wiring, at $4,520 on average.

Generator size and price

Manual vs. automatic

Angi lists manual-start generators at $500 to $2,000 and automatic-start units at $2,000 to $30,000. HomeGuide puts a portable generator at $500 to $2,500 plus $400 to $1,300 for its transfer switch.

Add-ons

A smart load manager runs $130 to $250 and a wireless monitor about $200 (HomeGuide). Angi lists smart load management at $150 to $300.

Running and upkeep costs

Angi lists propane at about $220 a day and diesel about $175 a day to run a 20 kW generator during an outage, and maintenance at $80 to $300. HomeGuide lists annual maintenance at $200 to $650 and a DIY maintenance kit at $20 to $110. Angi gives battery backup as an alternative at $10,000 to $25,000.

What a transfer switch does

A transfer switch safely connects a generator to your home's wiring. It keeps generator power from feeding back into the utility lines, which can endanger line workers, and it keeps utility power from damaging your generator.

More on manual vs. automatic

• Manual transfer switch: you start the generator and flip the switch yourself. Common with portable generators.
• Automatic transfer switch: senses an outage, starts a standby generator and switches power automatically.

Interlock kits

An interlock kit is another option for portable generators. It mounts on the panel and stops the main breaker and generator breaker from being on at the same time. Check local code rules first.

What affects the price

• Switch type and size.
• Number of circuits powered.
• Generator inlet box outside the house.
• Panel condition and location.
• Permit and inspection.

Never backfeed

Plugging a generator into a household outlet with a double-ended cord is dangerous and illegal in many places. A transfer switch or interlock is the safe way.

Questions to ask

1. Which circuits should the generator power?
2. Is my generator large enough for those circuits?
3. Will you install an inlet box outside?

In Texas

Since the February 2021 winter storm, many Texas homeowners have added backup power. A properly installed transfer switch makes a portable generator much safer to use during outages.

How installation is done

Installing a transfer switch starts with a load calculation and a decision about which circuits need backup power. For a manual switch with a portable generator, the electrician mounts the transfer switch next to the main panel, moves the selected circuits from the panel to the switch, and installs a power inlet box on the outside wall where the generator cord plugs in. For an automatic switch with a standby generator, the switch is wired between the utility meter or main panel and the generator, along with control wiring that lets the generator start on its own when utility power drops.

The work requires shutting off power to the house for part of the day. Afterward, the electrician tests the switch by simulating an outage and confirming that the selected circuits run on generator power and return to utility power cleanly. Most areas require a permit and an inspection for this work, and many utilities want to be notified.

Choosing which circuits to back up

With a smaller generator, you cannot run everything at once, so you choose the essentials. Common choices are the refrigerator and freezer, a few lighting circuits, the furnace blower or a window air conditioner, the well pump if the home has one, the sump pump, internet equipment and a few outlets for phones and medical devices. Electric water heaters, ranges, dryers and central air conditioners draw a lot of power and are often left off unless the generator is large.

Write the list down before the electrician arrives, and walk through how you would actually live during a multi-day outage. That list determines the size of the switch and the generator.

Using a portable generator safely

• Run the generator outdoors, far from doors, windows and vents. Carbon monoxide from generators kills people every year, often in garages with the door open.
• Install battery-powered carbon monoxide alarms inside the home.
• Use a properly rated generator cord to connect to the inlet box, not a homemade cable.
• Turn off the main breaker or switch to generator mode before connecting, exactly as the electrician showed you.
• Let the generator cool before refueling, and store fuel safely away from the house.

Maintaining the setup

Start a portable generator every month or two and run it under some load, so the engine stays in working order and stale fuel does not clog the carburetor. Use fuel stabilizer if gasoline will sit for a while. Test the transfer switch at the same time, so you know the process when the power is actually out. A standby generator runs an automatic exercise cycle, but it still needs regular oil changes and service according to the manufacturer.

Sources

1. HomeGuide: How Much Does a Whole House Generator Cost (Dec 30, 2025)
2. Angi: Whole House Generator Cost (updated Sep 1, 2026)