Manual Transfer Switches for Portable Generators
A manual transfer switch lets you run a chosen set of house circuits off a portable generator by flipping them from utility to generator power yourself. It's the standard, code-friendly way to power a furnace, well pump or fridge in an outage, and installed it usually costs $400 to $1,300.
The alternative is an interlock kit on your main panel. Both are safe when installed right. Which one wins depends on your panel and how many circuits you want.
How a manual transfer switch works
Most manual switches are a small subpanel mounted next to your main panel. The electrician moves the circuits you choose (furnace, fridge, well pump, a few lights) out of the main panel and through the switch. Each circuit gets a selector that's either on LINE (utility) or GEN (generator), never both.
Outside, a power inlet box gives the generator cord somewhere to plug in. Generac sells HomeLink bundles that add a power inlet box (resin or aluminum) and a 30- or 50-amp generator cord to the switch. Generac says its switches prevent back-feeding that could injure utility line workers.
Types of manual switches
| Type | What it covers | Good for |
|---|---|---|
| Pre-wired circuit-selector switch | Generac's come in 8 to 10 and 10 to 16 circuit versions | Most portable generator setups |
| Single-load switch | Generac lists single-load switches at 60 and 100 amps | One big load, like a well pump or a subpanel |
| Small one- or two-circuit switch | Generac lists a 30-amp version | A furnace or one appliance |
| Whole-house manual switch | Generac lists 200-amp utility side with a 30- or 50-amp generator side | Sending the generator to the whole panel |
| Meter-base switch | Mounts at the meter socket | Homes where the panel can't be reworked |
The circuit-selector switch is the right pick for most homes. It's simple, it forces you to choose essential loads, and it keeps you from overloading the generator by accident.
A whole-house manual switch sounds better than it is with a portable generator. The generator still can't run everything at once, so you end up turning breakers off in the main panel anyway. Meter-base switches need the utility's blessing because they sit at the meter. Ask the utility before you buy one.
30, 50 or 100 amp: matching the generator
The switch's generator side has to match the generator's biggest outlet and the cord between them. Generac's HomeLink switches come in 30-amp and 50-amp models for exactly that reason. Read the amp rating on the generator's largest locking outlet and buy the switch, inlet and cord at that same rating.
HomeGuide's unit prices by rating, before installation:
| Rating | Switch only |
|---|---|
| 30 amp | $200 to $500 |
| 50 amp | $260 to $900 |
| 100 amp | $300 to $950 |
| 200 amp | $680 to $1,500 |
On circuit count, Angi pairs generators up to 5,000 watts with 6 to 10 circuits, and 5,000 to 10,000 watt generators with 10 to 16. Pick the circuits before you pick the switch. Not sure the generator can carry what you want? Run the numbers in the generator sizing guide.
Manual switch, interlock or automatic
| Option | Installed cost | Best fit |
|---|---|---|
| Manual transfer switch | $400 to $1,300 | Portable generator, set list of circuits |
| Interlock kit | $400 to $850 | Portable generator, panel with a listed kit |
| Automatic transfer switch | $600 to $2,500 | Standby generator only |
An interlock kit gives you access to every breaker in the panel, which is handy, but it only works if your panel maker lists a kit for it. A manual switch works with almost any panel. Automatic switches need a generator that can start itself, which most portables can't. See interlock kit vs transfer switch for a deeper comparison.
How to use a manual transfer switch
The exact steps are in your switch's manual. The usual sequence for a circuit-selector switch:
- Set the generator outside, well away from the house, with the exhaust pointed away from windows and doors.
- With the generator off, plug the cord into the generator and the inlet box.
- Start the generator and let it run a minute to settle.
- Move the circuits from LINE to GEN one at a time, starting with the biggest motor loads like the well pump or furnace. Honda's sizing advice is to stagger appliances with a high starting draw rather than start them together.
- Watch the generator. If it bogs down, switch a circuit back off.
- When utility power returns, move every circuit back to LINE, then shut the generator off and unplug the cord.
Generac's HomeLink models use a rocker switch to move power between utility and generator, with indicator lights showing which source is live. Read the label on yours before the first outage, not during it.
Installation and cost
Most of the bill is the electrician. Angi puts basic transfer switch installation at $200 to $500, at $50 to $100 an hour, and most installs take two to four hours. Permits run $50 to $350. A full or outdated panel adds cost, with a subpanel at $400 to $1,750.
Generac markets its pre-wired kits as quick to install. That's true for an electrician. For a homeowner, it still means pulling circuits out of a live panel and drilling through the wall for the inlet. Hire it out, and ask the electrician to label every circuit at the switch.
Reliance Controls is the other name you'll see on these switches, and its kits fill the same role. Match the switch to the generator outlet, and buy the inlet and cord to match.
FAQ
Does a portable generator need a transfer switch?
Only if it's going to power hard-wired equipment or house circuits. Extension cords straight to a fridge or a lamp don't need one. Anything connected to your panel needs a transfer switch or a listed interlock so the generator can't backfeed the grid.
How do you use a Generac manual transfer switch?
Plug the generator into the inlet, start it, then use the switch to move power from utility to generator. Generac's HomeLink models use a rocker switch with lights that show which source is on. Bring loads on one at a time, and reverse the steps when the power returns.
How much does a Generac transfer switch cost?
It depends on the model and rating. HomeGuide prices manual switches at $200 to $800 for the unit alone, and Angi puts a manual switch at $400 to $1,300 installed. Get the installed price from your electrician, since labor and the inlet box make up much of the total.
How many circuits do I need?
Count the loads you can't do without: furnace, fridge, freezer, well pump, sump pump and a few lights and outlets. Angi pairs 6 to 10 circuits with generators up to 5,000 watts. Buy a switch with a couple of spare slots.
Sources
- AngiHow Much Does It Cost to Install a Generator Transfer Switch? (opens in a new tab)
- HomeGuideGenerator Transfer Switch Installation Cost (opens in a new tab)
- GeneracHomeLink Transfer Switches (opens in a new tab)
- GeneracPortable Generator Transfer Switches (opens in a new tab)
- Honda Power EquipmentHow Much Power Do You Need? (opens in a new tab)