Is it safe to run my portable generator during a power outage without a transfer switch?

No — running a portable generator without a properly installed transfer switch is extremely dangerous and illegal in Ontario. If you plug a generator directly into a wall outlet or wire it into your panel without a transfer switch, you create a condition called backfeed that sends electricity out through your meter and onto the neighbourhood power lines. This can electrocute Toronto Hydro line workers who are working to restore power, and it is a criminal offence under Ontario law.

Backfeed is the single most dangerous mistake homeowners make with portable generators, and it has killed utility workers across North America. When power goes out during one of Toronto's ice storms — the kind that left over 300,000 Toronto Hydro customers without power for up to 10 days during the 2013 event — the temptation to connect a generator any way possible is understandable. But the consequences of backfeeding are lethal. Toronto Hydro workers assume that downed or de-energized lines are safe to work on. A backfed generator on your street can re-energize those lines at potentially lethal voltages. The transformer on the pole that normally steps down 7,200 volts to your 240-volt service works in both directions — your generator's 240 volts gets stepped up to 7,200 volts on the primary lines.

A transfer switch is a device installed at your electrical panel that physically disconnects your home from the Toronto Hydro grid before connecting the generator. This makes it mechanically impossible for generator power to feed back onto the utility lines. There are two types: a manual transfer switch (also called a transfer panel), which requires you to physically flip switches to select which circuits receive generator power, and an automatic transfer switch, which detects a power outage and switches over automatically. For portable generators, a manual transfer switch is the standard approach and costs $1,500 to $2,500 installed by a licensed electrician, including the ESA permit and inspection.

The safe way to use a portable generator without a transfer switch is to run extension cords directly from the generator to individual appliances — never through the house wiring. The generator must be outdoors, at least 3 metres from any window, door, or vent, and never in a garage, basement, or enclosed space. Carbon monoxide from generator exhaust is odourless and deadly, and the Ontario Fire Code requires CO alarms near all sleeping areas. Even during a winter power outage, the generator must stay outside. Every year in Ontario, homeowners die from carbon monoxide poisoning because they ran a generator indoors during an outage.

If you are considering generator backup for your GTA home — and given Toronto's vulnerability to ice storms, it is a wise investment — have a licensed electrician install a proper transfer switch. The ESA requires a permit for this work, and the installation will be inspected to confirm it meets the Ontario Electrical Safety Code. Toronto Electrical Repair can match you with licensed electricians experienced in generator installations across the Greater Toronto Area.