What type of electrical wire do I need for outdoor circuits in Toronto?

For outdoor circuits in the GTA, you need weather-rated wiring such as TECK cable for direct burial or NMD90 run through approved outdoor conduit (rigid PVC or rigid metal). Standard NMD90 cable cannot be exposed to weather or buried directly in the ground — it must always be protected inside conduit when used outdoors.

The most common approach for residential outdoor circuits in Toronto is running NMD90 cable through Schedule 40 rigid PVC conduit from your main panel to the outdoor location. The conduit protects the wire from moisture, UV exposure, physical damage, and the freeze-thaw cycles that define GTA winters. Any conduit buried underground must be installed below the frost line, which is 48 inches (1.2 metres) in Toronto — this is non-negotiable under the Ontario Electrical Safety Code. If you bury conduit shallower than 48 inches, frost heave will shift and crack it over time, exposing the wiring to moisture infiltration and ground movement.

For longer outdoor runs — say, powering a detached garage, garden shed, or a landscape lighting transformer at the far end of your property — TECK cable is often the better choice. TECK cable has an armoured jacket and moisture barrier that allows direct burial without conduit, though it still needs to be buried to frost depth. It costs more per foot ($3 to $10 depending on gauge) but saves the labour of installing and gluing conduit over a long run. Your electrician will calculate the voltage drop over the distance to ensure the wire gauge is sufficient — on runs over 30 metres, you may need to upsize the wire to compensate for voltage loss.

All outdoor wiring connections must be made inside weatherproof (WP-rated) junction boxes and enclosures. Standard indoor electrical boxes are not rated for outdoor use and will corrode within a season or two in Toronto's humid summers and salt-laden winters. Look for boxes rated NEMA 3R or better for outdoor electrical enclosures. Every outdoor outlet must be protected by a GFCI breaker or GFCI receptacle — this is an absolute code requirement, and the GFCI must be the in-use type with a weatherproof cover that seals even when a cord is plugged in.

Seasonal Timing for Outdoor Electrical Work

The best time to schedule outdoor electrical installation in the GTA is late spring through early fall (May to October). Digging to 48-inch frost depth is significantly harder and more expensive when the ground is frozen, and conduit adhesives and sealants perform poorly in cold temperatures. If you are planning a deck, patio, or backyard renovation that includes electrical work, coordinate the electrical trenching with your landscaping or hardscaping contractor to avoid tearing up finished work later.

An ESA permit is required for all new outdoor circuits, and your electrician handles the permit application and coordinates the inspection. Expect permit costs of $100 to $250 for a typical outdoor circuit addition. Toronto Electrical Repair can match you with a licensed electrician experienced in outdoor installations — browse the Toronto Construction Network directory to find electrical professionals in your area.