Generator transfer switch Canada

Quick answer

A transfer switch or approved interlock lets a generator safely power selected household circuits without backfeeding the grid. This is not a DIY wiring project. It is electrical work, and it should be handled by a licensed electrician according to local requirements and permits.

What you need to know:

• A transfer switch prevents generator power from feeding back into the utility grid.
• Backfeeding can injure or kill utility workers, damage equipment, start fires, and is illegal in most jurisdictions.
• This page is an explainer — not a wiring tutorial. No installation steps are provided.

What a transfer switch does

A transfer switch or interlock separates your generator from the utility grid. When the grid goes down, the switch or interlock disconnects your home from the utility lines and connects selected circuits to the generator. When grid power returns, it reverses the process.

Without this separation, generator power can flow backward through your panel, out to the transformer, and energize utility lines. This is backfeeding, and it is dangerous.

What a transfer switch is not:

• It is not a way to backfeed your panel through a dryer outlet.
• It is not a suicide cord.
• It is not a YouTube wiring hack.
• It is not a DIY weekend project.

Transfer switch vs interlock

These are the common ways to connect a generator to household circuits safely. Each has trade-offs.

Option	What it does	Typical use	Pro install required
Manual transfer switch	A separate panel that moves selected circuits from utility to generator	Portable generator setups with a dedicated sub-panel	Yes
Generator interlock	A mechanical bracket that prevents the main breaker and generator breaker from being on simultaneously	Panel-specific setups without a sub-panel	Yes
Automatic transfer switch	Detects utility loss and switches to generator power automatically	Standby generators with automatic start	Yes
Generator inlet + cord	A power inlet box installed outside, connected through a transfer switch or interlock	Allows safe cord connection without opening the panel	Yes
Extension cords only	Plug appliances directly into the generator	Temporary outdoor generator use, no household wiring involved	No

Manual transfer switch: A licensed electrician installs a small sub-panel beside your main panel. Selected circuits are moved into the sub-panel. When the grid is down, you switch those circuits to generator power. This is clean, code-compliant, and straightforward for portable generators.

Generator interlock: A mechanical bracket or sliding plate is installed on the main panel. It physically prevents the main breaker and a generator backfeed breaker from both being on at the same time. This is simpler and less expensive than a sub-panel, but not all panels support it. Your electrician can tell you if an interlock is an option for your panel model and local jurisdiction.

Automatic transfer switch (ATS): Used with standby generators. When the grid goes down, the ATS signals the generator to start and switches the load automatically. This is a different category — higher cost, professional design, and often running on natural gas or propane.

Why backfeeding is dangerous

Backfeeding is what happens when you connect a generator to household wiring without a transfer switch or interlock. The generator pushes power backward through the panel and out to the utility grid.

What backfeeding can do:

• Energize utility lines that utility workers assume are dead. This can injure or kill linemen working to restore power.
• Energize nearby homes through shared transformers. Neighbours doing their own electrical work could be injured.
• Damage your generator when utility power is restored, since the sudden reconnection can fry the generator’s internal components.
• Start a fire due to overloaded wiring, improper connections, or incompatible equipment.
• Void your home insurance if improper generator wiring causes damage or injury.

Backfeeding is illegal in most Canadian jurisdictions because of these risks. Electrical codes, local bylaws, and utility rules all require proper transfer equipment for generator-to-panel connections.

What to ask an electrician

When you call an electrician about generator transfer equipment, these questions will help both of you get to the right answer faster:

• What loads do I want to run? Fridge? Freezer? Sump pump? Furnace blower? Well pump? Lights? Router? List everything so the electrician can size the equipment.
• Portable or standby generator? If you already have a portable generator, the conversation starts from there. If you are choosing a generator too, the electrician can advise on inlet and transfer requirements.
• Manual transfer switch or interlock? Not every panel supports an interlock. The electrician can tell you what is compatible and what the local code allows.
• Where should the generator inlet go? The inlet needs to be on an exterior wall near where the generator will sit — outside, away from windows, doors, and vents. The electrician can pick the best location.
• Is my panel capacity and condition adequate? Older panels or panels at capacity may need an upgrade before adding transfer components.
• Are permits and inspection required? Most jurisdictions require permits and electrical inspection for panel work. Ask about this upfront.
• Where will the generator sit for safe operation? The generator must be placed outside, well away from building openings, to prevent CO from entering the home. Discuss this with the electrician so cord routing and inlet placement align.
• Can I expand later? If you might upgrade to a larger generator or add a standby unit, some solutions accommodate future expansion more easily.

What not to do

This page exists because people die and property gets damaged when generators are connected improperly. Here is a hard list of things that should never happen:

Canada context

Canadian context

Electrical codes, utility rules, and inspection requirements vary by province and municipality in Canada. There is no single answer that applies to every home.

• Provincial electrical codes — most provinces adopt the Canadian Electrical Code (CE Code) with provincial amendments. Your electrician will know the local requirements.
• Utility rules — some utilities have specific requirements for generator interconnects. Your electrician should coordinate with or inform the utility.
• Permits and inspection — most jurisdictions require a permit and electrical inspection for panel work, transfer switch installation, or inlet addition. Do not skip this.
• Insurance — check with your home insurer about requirements for generator connections. Improper installation can void coverage.
• Canadian certification — transfer switches, interlocks, inlets, and generators should carry recognized Canadian certification marks (CSA, cUL, cETL) as recommended by Health Canada.

This information is educational. It is not legal advice or code interpretation. Consult a licensed electrician and your local inspection authority.

Frequently asked questions

Do I need a transfer switch for a portable generator?

If you only plug appliances directly into the generator using extension cords, you do not need a transfer switch. If you want generator power to flow through household circuits, you need a transfer switch or approved interlock installed by a licensed electrician.

Is a generator interlock legal in Canada?

It depends on your panel model, provincial electrical code, and local jurisdiction. Some panels and regions permit interlocks; others do not. A licensed electrician can tell you whether an interlock is an option for your panel and location.

Can I install a transfer switch myself?

No. Transfer switch installation involves working inside your electrical panel and modifying household wiring. This requires a licensed electrician, permits, and inspection in most jurisdictions. This page does not provide installation instructions.

What is backfeeding?

Backfeeding is when generator power flows backward through your panel and out to the utility grid. This can energize utility lines, injure or kill utility workers, damage equipment, and start fires. It is dangerous and illegal in most jurisdictions.

Can I plug a generator into a dryer outlet?

No. This is backfeeding. It energizes the wiring in your home and the utility lines outside. It bypasses safety mechanisms, creates fire and electrocution risks, and is illegal.

What should I ask an electrician?

Start with the list above: what loads to run, portable vs standby, manual switch vs interlock, inlet location, panel condition, permits, CO-safe generator placement, and future expansion. A good electrician will walk through these with you.