Markham · Alectra Utilities service area
Rewiring and new circuits for Markham homes
Markham's wiring runs from heritage houses on its old main streets to homes finished last year. We find out what's behind your walls first, then plan a full rewire, a partial one or just the circuits you need.
Markham's oldest wiring
Heritage houses, layered wiring
Unionville and Markham Village were farm villages long before the subdivisions came. Some houses near their main streets date from the 1800s. Their wiring was added later, and then changed again with each owner.
That means one house can hold several eras at once. Knob-and-tube from early in the last century may still run to an upstairs bedroom. Newer cable may feed the kitchen. Splices may hide in places nobody has opened in decades.
Knob-and-tube has no ground wire, and it was never meant to be covered in insulation. Some homes from the late 1960s and 1970s were built with aluminum branch wiring. Neither means the house is unsafe today, but you should know before you renovate or insure it. An electrical inspection gives you that answer.
By era
What we expect to find in Markham walls
A general Ontario guide by age of the house. Yours may have been changed since.
| Built | Where in Markham | Wiring you may find | Usual next step |
|---|---|---|---|
| Before the 1950s | Heritage houses in Unionville and Markham Village | Possible knob-and-tube, often partly replaced | Inspection, then a full or partial rewire |
| 1950s to 1970s | Older streets around the village cores | Early grounded copper, aluminum in some later homes | Inspection, then targeted work |
| 1980s and 1990s | Milliken, Buttonville, much of Unionville | Grounded copper | New circuits as needs change |
| Late 1990s onward | Cornell, Berczy, Wismer, Greensborough, Box Grove | Grounded copper at builder minimums | Extra circuits and outlets |
Living through it
How we rewire a Markham home you're living in
Trace every circuit
We map what feeds what, and mark the old runs that must come out.
Set the order
We work room by room, so you always have a kitchen and somewhere to sleep.
Pull new cable
Grounded circuits go in from the basement and attic, with small, clean openings where needed.
Land and label
Each circuit ends at the panel with a directory that matches the house.
Inspection
ESA inspects, and the Certificate of Acceptance is yours to keep.
Newer homes
Adding circuits in Markham's newer communities
Homes in Cornell, Berczy Village, Wismer and Greensborough are wired with grounded copper. They rarely need rewiring. What they need is more: a circuit for a home office, outlets on a kitchen island, power for a basement gym, or a line out to the garage.
Many of these homes have finished basements with drywall ceilings, which can make routes harder to find. We plan them from the panel outward and open as little as we can. If the panel has no room left, see panel upgrades in Markham first.
Questions
Wiring and rewiring in Markham: questions
Could an old house in Markham Village still have knob-and-tube wiring?
It's possible in any Ontario home built before the 1950s, even after earlier renovations. Clues include two-prong outlets and porcelain knobs in an open basement or attic. An electrical inspection is the only reliable way to know how much is left.
Should I worry about aluminum wiring in a 1970s Markham home?
Aluminum branch wiring was used in some Ontario homes in the late 1960s and 1970s. It isn't automatically dangerous, but its connections need the right devices and care. An inspection shows whether you have it, and we explain the options from there.
We want a home office and a basement gym in our Wismer house. Is that a rewire?
No. Wiring in homes of that age is grounded copper and normally sound. We add the new circuits you need from the panel, and check first that the panel has the spaces and capacity for them.
Do you take out the ESA permit?
Yes. In Ontario, the licensed contractor files the notification of work with the Electrical Safety Authority (ESA) and books the inspection. We handle it on every job that needs one, and you get the ESA Certificate of Acceptance when the work passes. Keep it: insurers and home buyers often ask for it.
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