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The transfer switch: the heart of the job

It’s the part that separates a properly connected generator from a deadly danger for Hydro-Québec line workers. And it’s most of the bill.

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By the master electricians of STM-ÉlectriqueRBQ licence 5815-0137-01Sources checked on September 11, 2026

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In short

It isolates your home from the grid while the generator runs.

Without it, the current can flow back to the line and electrocute a line worker.
At STM-Électrique, the price of a 60 amp manual switch or an automatic one, installed and connected, is in the written quote, free of charge. The generator, its base and the fuel are extra.
It’s what determines which circuits are backed up.
The quote prices the switch installed. The generator is extra.

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What it does
Backfeed
Manual or automatic
Circuits to back up
During an outage
Cost
Frequently asked questions

What it does

When you shop for a generator, you compare machines. When you have it installed, you discover that the part that matters most isn’t the generator: it’s the grey box mounted next to the panel.

A transfer switch does one thing, and it does it absolutely: it guarantees that your installation is never supplied by two sources at the same time. Either the grid or the generator. Never both.

When the grid goes down, it opens the link to Hydro-Québec and closes the one to the generator. When power comes back, it does the reverse. In between, there is no position where the two sources touch.

It’s also what defines the scope: the circuits connected to the switch are backed up, the others aren’t.

Backfeed, the real danger

Here is why this part isn’t a paperwork formality.

During an outage, a Hydro-Québec line worker works on a line they have de-energized and know to be dead. If a generator somewhere on that section is connected without isolation, its current flows back into the grid. It goes through the neighbourhood transformer in reverse, which makes it come out at a voltage much higher than the house’s.

The line worker touches a conductor they checked dead ten minutes ago.

That’s why a portable generator is never plugged into a dryer outlet or an ordinary outlet with a double male cord. That setup has a name in the trade, and it isn’t a compliment. It kills people who have nothing to do with your house.

Backfeed is dangerous for you too: when grid power returns, two sources meeting destroys the generator, and sometimes starts a fire.

Manual or automatic

	Manual	Automatic
Who switches over	You, by hand	The switch, on its own
Delay	The time it takes you to get there	A few seconds
If you’re away	Nothing happens	The house is backed up anyway
Goes with	A portable, in general	A standby unit
At STM-Électrique	Price in the quote (60 A, installed)	Price in the quote (installed)

A manual switch isn’t a bargain-bin product: it’s the right choice when the generator is portable and someone is there to start it anyway. An automatic switch is justified as soon as the house has to be protected while you’re away: a basement with a sump pump, a cottage, or simply people who travel.

Choosing the circuits to back up

This is the part of the conversation that has the most effect on the total price, and the one people don’t anticipate.

The switch has a capacity, expressed in amps: 60 amps, for example. That capacity sets the number and type of circuits that can be connected to it. The more you want to back up, the bigger the switch has to be, and the bigger the generator to keep up with it.

The list we usually build, in order:

The sump pump. The one that prevents water damage, and so the claim.
Heating, or at least the furnace controls.
The refrigerator and the freezer.
A few lighting and outlet circuits, so the house stays liveable.
The well pump, if you’re not on the municipal water system: without it, no water at all.

What we leave aside without regret: the dryer, the oven, the hot tub, the EV charger. They are heavy loads nobody needs during an outage.

During an outage: the steps, in order

Here is the procedure with a generator panel and an outdoor power inlet. It’s the one we show you at the end of the installation.

When Hydro-Québec’s power goes out

Place the generator outdoors, at least 6 metres from buildings, with the exhaust pointing away from doors and windows. Never run it in a garage or a shed.
Turn the breakers of the backup circuits OFF.
With the generator off, connect the compatible cord between the generator and the outdoor power inlet.
Start the generator and let it stabilize according to the manufacturer’s instructions.
Put the transfer switch in the “Generator” position, following the procedure we showed you.
Turn the chosen circuits back ON one at a time, staying within the available output. The appliances running at the same time must stay within that limit.

When power comes back

Put the transfer switch back in the “Hydro-Québec” or “Utility” position, depending on your model.
Let the generator run without load according to the manufacturer’s instructions, then stop it.
Unplug the cord and close the cover of the outdoor inlet.

Good to know: the controls and the exact procedure vary by model. Follow your electrician’s demonstration and the manufacturer’s instructions. The 6 metre distance is the one recommended by Health Canada to prevent carbon monoxide poisoning.

Ready to ask for prices?

We take a look, we price it, and the price is in writing before anything starts.

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What it costs

At STM-Électrique, for a single-family home:

Switch	Price, installed	When it’s the right choice
Manual, 60 amps	price in the quote	With a portable, someone on site
Automatic	price in the quote	With a standby unit, house protected at all times

The quote covers the switch installed and connected. The generator, its base and the fuel are extra: it’s a machine you buy, and its price depends entirely on the model and the output chosen.

What changes the installation: the distance between the panel and the location, the number of circuits to move to the backup panel, the condition of and room in your current panel, and the municipal permit. If your panel is already full, it becomes a bigger conversation: see our guide replacing an electrical panel.

Rénoclimat: up to $1,000 for the hookup. Since October 1, 2026, Rénoclimat pays up to $1,000 toward the labour of a master electrician who connects a backup power source to the panel of your principal residence, a duplex, a triplex or a building with at least four units. The Québec government describes this measure as connecting a backup power source “powered by renewable energy”: for a generator, have Rénoclimat confirm it qualifies before counting on this rebate. The home must have been built and lived in for at least five years. The rebate doesn’t cover buying the generator or the transfer switch. You apply yourself, no later than 12 months after the work. Rénoclimat 2026: up to $1,000 to hook up a backup power source

Frequently asked questions

Is the transfer switch mandatory?

To connect a generator to the house wiring, yes. It’s what guarantees that the two sources never meet. A connection without isolation endangers Hydro-Québec line workers and destroys the equipment when power returns.

Manual or automatic?

Manual if the generator is portable and someone is there to start it anyway. Automatic as soon as the house has to be protected while you’re away: a sump pump that stops while you’re travelling means water damage.

How many circuits can be backed up?

It depends on the capacity of the switch and the output of the generator, which have to go together. It’s the point in the conversation where we set your priorities: the sump pump and the heating first, comfort after.

Can it be added to a generator I already bought?

Yes, it’s even a common case: someone buys a portable after an outage, then realizes they can’t do anything with it without a hookup. The switch is then chosen based on the machine already there.

Does the power have to be cut to install it?

Yes, while we work in the panel and move the circuits to be backed up. How long depends on the number of circuits: a few hours in most cases, and you get the time window before the work.

Can I install it myself?

No. It’s work in the panel, on the service, that requires an RBQ licence. And it’s precisely the part where a mistake endangers people who aren’t in your home.

Does it need maintenance?

Little, but not none. An automatic switch takes part in the generator’s test cycle; a manual one benefits from being operated once a year to check that it switches without forcing. It takes two minutes and avoids a surprise in the middle of an outage.

A generator to connect?

We build the list of circuits to back up with you, size the switch accordingly, and the price is in writing before anything starts.

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Sources

The figures and requirements cited in this guide come from the official pages below, consulted on September 11, 2026. Programs change: check the page’s update date before committing to any expense.