Garage Wiring in Edmonton: Subpanels, Heaters and Block Heater Outlets

In Edmonton, the garage works harder than almost any other room in the house. It keeps the car out of the snow, holds the freezer and the tools, and for a lot of people it is a workshop, a gym or a place to park an EV. Most garages were wired for one light bulb and a door opener. If yours is starting to trip breakers, run on extension cords, or stay too cold to use from November to March, here is what proper garage wiring looks like and how to plan it.

Signs your garage wiring is not keeping up

Most of the garage calls we get in Edmonton start with one of these:

• Breakers tripping: the garage shares a single 15 amp circuit with the front porch light, the outdoor outlets and sometimes a bedroom. Run a shop vac and a heater at the same time and it is lights out.
• Extension cords everywhere: a cord across the floor to the freezer, another one out the side door to the car. Cords are meant for temporary use. Left in place through a winter, they crack, get pinched under the door and overheat.
• One outlet for everything: plenty of older Edmonton garages have a single receptacle on the back wall and one on the ceiling for the opener.
• Too dark to work: one bare bulb in the middle of a two car garage puts your workbench in its own shadow.
• Too cold to use: if the garage sits at minus 20 for weeks, the workshop, the gym and the hobby space all shut down for the season.

Attached vs detached garages

How we wire a garage starts with whether it is attached to the house or sits out back by the lane, which is common in older neighbourhoods like Westmount, Strathcona and Glenora.

• Attached garages: new circuits usually run straight from the main panel through the wall or ceiling. If the panel is on the garage wall, this is often the simplest garage job there is. If the panel is at the far end of the basement, we plan the route so nothing ends up exposed where it can be damaged.
• Detached garages: power has to travel from the house to the garage, usually underground. That means a trench, a cable or conduit rated for burial, and a feed sized for everything you want to run out there. Older detached garages often have a single undersized cable strung overhead or buried shallow years ago. If you are adding real load, that feed usually needs to be replaced.

Do you need a garage subpanel?

A subpanel is a small breaker panel in the garage fed by one larger circuit from the main panel in the house. Instead of running six separate circuits across the yard or through the house, you run one feed and split it into circuits right where you need them.

• You probably need one if: the garage is detached and you want more than one or two circuits, you are adding a 240 volt heater, a welder or a large compressor, or you plan to add an EV charger later.
• You probably do not if: the garage is attached, the main panel has open breaker spaces, and you only need a couple of new outlets and better lighting.
• Sizing: the subpanel and its feed are sized to the load you plan to run. A workshop with a heater and a few tools needs a lot less than a garage with a heater, a welder and a Level 2 charger. We size it for what you have today plus what you tell us is coming, so you are not trenching the yard twice.

Before any of that, the main service has to be able to carry the extra load. We do a load calculation on the house first. If a 60 or 100 amp service is already close to its limit, the garage project may be the push to look at a panel upgrade.

Heating the garage in an Edmonton winter

Heat is the biggest reason Edmonton homeowners call us about the garage. There are two common setups, and both need an electrician.

• Electric unit heaters: a 240 volt heater mounted high on the wall or ceiling with its own thermostat. These are clean, quiet and simple, but they draw a lot of power and need a dedicated circuit sized to the heater. In a detached garage this is usually what tips the job into needing a subpanel.
• Gas unit heaters: the gas fitter handles the gas line and venting, but the heater still needs a 120 volt circuit for the blower and controls. We coordinate with your gas fitter so the circuit and thermostat are ready when the heater goes up.
• Insulation first: an uninsulated garage door will swallow any amount of heat. If the walls, ceiling and door are not insulated, put that on the list before you size a heater.

Block heater outlets that actually work at minus 30

Every Edmonton driver knows the routine. Plug in the block heater when it drops to around minus 15 and colder. What a lot of people do not realize is how much a bad outlet setup costs them.

• A proper outdoor receptacle: if you park on the driveway, you want a weatherproof outlet on the garage or house wall near where the car sits, with an in use cover that stays closed while the cord is plugged in. That beats a cord snaked through the side door every night.
• Enough capacity: a block heater draws a steady load for hours. Two vehicles plugged into the same circuit as the garage lights and a freezer is a common reason for breakers tripping at 6 AM.
• Timers: most block heaters only need two to four hours before you leave. A heavy duty outdoor timer or a timer switch inside the garage means the car is warm when you need it without running all night.
• Protection: outdoor and garage receptacles need GFCI protection under the electrical code. We make sure the right protection is in place so a wet cord or a frozen plug does not turn into a shock hazard.

Outlets, lighting and the workshop

Once the power is in the garage, the rest of the plan is about putting it where you will use it.

• Workbench circuits: a row of outlets along the bench on its own circuit, so the saw and the dust collector are not fighting the freezer. Big stationary tools may each need their own circuit.
• 240 volt outlets: welders, large compressors and some table saws run on 240 volts. We install the right receptacle for the tool and size the circuit to match its nameplate.
• The freezer: a dedicated outlet for the chest freezer, so nothing else on the circuit can trip it while you are away.
• Lighting: LED shop lights or linear fixtures spread across the ceiling give even light with no shadows over the bench or the car. Add a light above the door and a switch at every entrance so you never walk in in the dark. Our lighting work covers both inside and outside the garage, and the outdoor lighting guide has more on driveway and security lights.
• Door opener: the opener should have its own ceiling receptacle right above the motor, not a cord running to a wall outlet.

Planning ahead for an EV charger

Even if you do not drive an electric vehicle yet, the garage project is the cheapest moment to get ready for one. If we are already running a feed and installing a subpanel, sizing it to carry a Level 2 charger later costs far less than redoing it in two years. Our EV charger guide covers charger sizing, and we can rough in the circuit now and install the charger when the car arrives. See our EV charger installation page for what that involves.

Permits and inspections

New circuits, a subpanel or a new feed to a detached garage all need an electrical permit with the City of Edmonton, and the work is inspected before it is closed up. We pull the permit, do the work to the Canadian Electrical Code, and book the inspection. For a detached garage, that includes locating buried utilities before anyone digs a trench.

Permitted work matters when you sell the house too. A home inspector who finds a garage full of unpermitted wiring and extension cords will flag it, and buyers notice.

The bottom line

A well wired garage is warm enough to use in January, bright enough to work in, and has an outlet wherever you need one, with no cords across the floor and no breakers tripping when the heater kicks on. Whether it is a single new circuit in an attached garage or a full subpanel and heater in a detached one, it starts the same way: we come out, look at your panel and your garage, and give you a written quote before any work starts. Our residential electrical page covers how we work, or call MSA Electrical to book a visit anywhere in Edmonton and the surrounding area.