What Is a Transfer Switch and Do I Legally Need One in Ontario?

What Is a Transfer Switch and Do I Legally Need One in Ontario?

A transfer switch is an electrical device that safely connects a generator to your home’s electrical panel. Without one, connecting a generator to your home wiring creates a serious hazard known as backfeed — electricity flowing back through the utility lines, which can electrocute utility workers restoring power after an outage. Here is what you need to know about transfer switches and Ontario’s requirements.

What Does a Transfer Switch Do?

A transfer switch disconnects your home from the utility grid before connecting the generator. This isolation prevents backfeed, protects the generator from utility voltage, and allows you to power selected circuits in your home safely. When utility power is restored, the switch transfers the load back to the grid and disconnects the generator.

Types of Transfer Switches

• Manual transfer switch — you physically operate the switch when the power goes out and when it returns. Less expensive than an automatic switch. Requires you to be present to activate it.
• Automatic transfer switch (ATS) — detects a power outage and automatically starts the standby generator and transfers the load, then switches back and shuts down the generator when utility power returns. Required for whole-home standby generators.
• Interlock kit — a mechanical device installed on the breaker panel that prevents the main breaker and the generator breaker from being on simultaneously. A lower-cost alternative to a full transfer switch for portable generator connections.

Is a Transfer Switch Legally Required in Ontario?

Yes. Connecting a generator to your home’s electrical wiring without a proper transfer switch or interlock is prohibited under the Ontario Electrical Safety Code (OESC). The Electrical Safety Authority (ESA) requires that any generator permanently connected to home wiring be installed with an approved transfer switch and an ESA permit.

Running a portable generator with extension cords plugged directly into outlets is permitted, but connecting it to the panel wiring — even temporarily — without an approved isolation method is not. A licensed electrical contractor must perform the installation and pull the required ESA permit.

Why Backfeed Is Dangerous

When a generator is connected to home wiring without a transfer switch, the power it generates can travel back through your meter and onto the utility lines. Utility workers working on those lines assume the lines are de-energized — backfeed can deliver lethal voltage to workers repairing the outage. This is why transfer switch isolation is a code requirement, not just a recommendation.

Get a Transfer Switch Installed by EZSMART

EZSMART installs manual and automatic transfer switches for portable and standby generators across Ontario. We handle the ESA permit and ensure the installation meets Ontario Electrical Safety Code requirements.

Contact us today to get a quote for transfer switch installation.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp