What are the Ontario code requirements for running electrical wire through a Toronto home's unheated garage?

Ontario code requires specific wiring methods and protection for unheated garage installations, with GFCI protection mandatory on all garage outlets and special considerations for wire types in spaces subject to freezing.

Running electrical wire through an unheated garage in the GTA involves several critical code requirements under the Ontario Electrical Safety Code (OESC). The primary concerns are protection from physical damage, moisture infiltration, and the freeze-thaw cycles that are particularly severe in Toronto's climate.

Wire Type and Protection Requirements

For exposed wiring runs in unheated garages, you must use armoured cable (AC90/BX) or run NMD90 cable through protective conduit. Standard NMD90 cable cannot be left exposed in garages where it's subject to physical damage from vehicles, tools, or stored materials. AC90 armoured cable provides the mechanical protection required and is rated for the temperature variations common in unheated Toronto garages. If running NMD90, it must be installed in rigid conduit (PVC or metal) and secured properly to prevent damage from thermal expansion and contraction during our harsh winter-to-summer temperature swings.

Underground or buried cable runs through the garage (such as feeding an outdoor circuit) require TECK cable, which is specifically designed for direct burial and wet locations. This is particularly important in Toronto garages where spring snowmelt and summer humidity create moisture concerns.

GFCI Protection and Outlet Requirements

All outlets in garages require GFCI protection without exception. This includes outlets for garage door openers, workbenches, electric vehicle charging, and general use. The GFCI protection can be provided either by GFCI breakers in the panel or GFCI outlets at each location. Given Toronto's humidity and the condensation that forms in unheated garages during temperature swings, this protection is critical for preventing electrocution.

The code requires at least one outlet in every garage, and it must be readily accessible (not behind stored items or requiring a ladder to reach). For attached garages, which are common in GTA suburban homes, the outlet must be GFCI-protected and located where it won't be blocked by a parked vehicle.

Temperature and Moisture Considerations

Toronto's climate creates unique challenges for garage electrical installations. Unheated garages experience the full range of outdoor temperatures, from -20°C winter lows to +35°C summer highs. Cable and connections must be rated for this temperature range. Standard NMD90 cable is rated to 90°C and handles our temperature swings well, but connections in junction boxes and panels can loosen during repeated thermal cycling.

Moisture infiltration is a constant concern in GTA garages. Spring snowmelt, summer humidity, and condensation from temperature changes create wet conditions. All junction boxes, outlets, and switches in unheated garages should be weatherproof or at minimum moisture-resistant. Outdoor-rated boxes and covers are often the best choice even for interior garage installations.

Circuit Protection and Capacity

Garage circuits typically require 20-amp protection, especially if serving multiple outlets or high-draw devices like electric vehicle chargers or workshop equipment. A dedicated 20-amp circuit using 12 AWG wire is standard for garage installations. If you're planning EV charging, that requires its own dedicated circuit sized for the charger's amperage requirements (typically 40-50 amps for Level 2 charging).

Installation Height and Accessibility

Outlets in garages must be installed at least 18 inches above the floor to prevent damage from water, snow tracked in by vehicles, and general garage floor moisture. This is particularly important in Toronto where road salt and winter slush are tracked into garages regularly. Switches and panels must remain accessible and cannot be blocked by typical garage storage.

Permit and Inspection Requirements

Any new electrical work in your garage requires an ESA permit and inspection. This includes adding outlets, upgrading circuits, or installing EV charging capability. The inspector will verify proper wire types, GFCI protection, appropriate mounting heights, and code-compliant installation methods. Given the safety concerns with garage electrical work, this isn't a DIY project—hire a licensed electrician who understands Ontario code requirements and Toronto's specific climate challenges.

Need help finding a licensed electrician for your garage electrical project? Toronto Electrical Repair can match you with local professionals experienced in GTA garage installations and code compliance.