What is a sub-panel and when would my home need one?

A sub-panel is a secondary electrical panel that draws power from your main panel and distributes it to circuits in a specific area of your home, such as a detached garage, basement suite, workshop, or addition. You would need one whenever you are adding significant electrical capacity to an area that is far from your main panel or when your main panel is physically full but still has available amperage.

Sub-panels are extremely common in GTA homes undergoing renovations or additions. If you are finishing a basement in a Mississauga or Brampton home and need six to ten new circuits for lighting, outlets, a bathroom fan, and a dedicated circuit for a space heater or mini-split, running all those circuits individually back to the main panel would be impractical and expensive. Instead, your electrician runs a single large feeder cable from the main panel to a sub-panel located in or near the basement, then runs all the new circuits from there. This saves on wire, reduces the number of long runs through your home, and keeps everything organized.

The same logic applies to detached garages and workshops. Many homeowners across Vaughan, Markham, and Richmond Hill want dedicated power for woodworking tools, EV chargers, or workshop lighting. A 60 amp or 100 amp sub-panel in the garage, fed by a properly sized feeder cable from the main panel, gives you room for multiple circuits without overloading anything. For a detached structure, the feeder cable typically runs underground in approved conduit, and your electrician will ensure proper grounding and bonding at the sub-panel location as required by the Ontario Electrical Safety Code.

One critical point that many homeowners miss is that your main panel must have enough spare capacity to support the sub-panel. If your main panel is rated at 100 amps and is already carrying a heavy load, adding a 60 amp sub-panel could push you past your service capacity. Your electrician will perform a load calculation to determine whether your existing service can handle the additional demand or whether you need a main panel upgrade first. In the GTA, a sub-panel installation typically costs $1,200 to $2,500, not including the main panel upgrade if one is needed. An ESA permit is required for all sub-panel installations. If you are planning an addition, garage conversion, or basement finish, Toronto Electrical Repair can match you with a licensed electrician who can assess your panel capacity and recommend the right approach.