Toronto · Toronto Hydro service area
Rewiring older Toronto homes, one floor at a time
A century semi or row house in Toronto often hides two or three generations of wiring behind its plaster. We find out what's there first, then replace it in planned phases with as few openings as the house allows.
What's behind the plaster
Wiring in a house with a long history
Much of the old city was built between the 1880s and the 1930s. Victorian and Edwardian semis and row houses fill the streets of Riverdale, Leslieville, Roncesvalles and the Danforth. Many were wired when electricity meant a ceiling light in each room and little else.
A century later, most of these houses carry a patchwork. Knob-and-tube may survive in a wall or two, early two-wire cable feeds the upper floors, and the last kitchen renovation brought modern grounded cable. In the Annex, plenty of large houses were split into flats or rooming houses and later turned back into family homes. Each change left circuits that no longer match the rooms.
Further out, Leaside and Davisville have detached homes and semis from the 1920s to the 1940s. East York has many smaller houses from the same years and just after the war. The wiring there is newer, but rarely ready for central air, an induction range and a home office.
Knob-and-tube is the earliest system: single wires on porcelain knobs, with no ground. A proper inspection is the only reliable way to know how much of it is still connected.
By house type
How a Toronto rewire changes with the building
The age of the house sets what we find. Its shape sets how the new cable gets in.
| Semi or row house | Older detached house | Condo apartment | |
|---|---|---|---|
| Main cable route | Up from the basement, down from a small attic or along the back wall | Basement, attic and closets stacked floor over floor | Partition walls, bulkheads and existing conduit |
| Usual obstacles | A masonry shared wall, a flat roof with no attic | Three storeys of plaster, a finished third floor | Concrete slabs, building work hours |
| Often needs work | Upper-floor bedrooms and the original kitchen | Mixed circuits from several renovations | Kitchen and bathroom circuits, older devices |
| Who else is involved | ESA | ESA | Property manager or board, and ESA |
Working in old walls
Fewer openings, neater patches
Plaster on wood lath cracks if it's cut carelessly, and the trim in a century home is hard to replace. We map each run before we drill. Cable is fished from the basement and the attic wherever the framing allows, and closets and baseboards hide many of the routes.
Some row houses have flat roofs and no usable attic. There, upper-floor circuits usually come up from below, and the second-floor ceiling may need a few small openings. Where an opening is needed, we cut it square and leave it ready for your plasterer.
If you're underpinning the basement or gutting the kitchen, rewire those spaces while they're open. It's the cheapest moment the house will offer.
In an occupied house
A phased rewire in a Toronto home
Map the circuits
We test and trace what feeds each room, floor by floor.
Set the phases
Kitchen, bathrooms and any worrying circuits first, the rest in a sensible order.
File with ESA
The notification of work goes in before any cable is pulled.
Replace and disconnect
New circuits go live and the old ones are removed from service so they can't be reused.
Inspect and hand over
ESA inspects, and you get the Certificate of Acceptance and a corrected panel directory.
Condos and the panel
Downtown units and full panels
In Yorkville, Davisville and downtown towers, rewiring is a different job. Nothing is fished through the concrete, so new circuits follow the partition walls and bulkheads. Older buildings sometimes have a small suite panel with no spare spaces, which limits how many circuits a renovation can add.
In houses, the panel matters just as much. A rewire adds breakers, and an old fuse box or a crowded 100 amp panel may have no room. If that's your house, the service and the wiring are often best planned as one project. See more on our work across Toronto.
Old panel?
Plan the service with the wiring
New circuits need somewhere to land. Upgrading the panel first means nothing is moved twice.
Panel upgrades in TorontoQuestions
Wiring and rewiring in Toronto: questions
Does rewiring my half of a semi affect the house next door?
No. Each side of a semi normally has its own service, panel and circuits, and we only touch yours. The shared wall is usually solid masonry, so we plan routes along the other walls instead. Your neighbour may hear drilling on work days, but their power stays on.
Can you rewire a condo unit downtown?
Usually, within the unit. Concrete floors and ceilings mean new cable runs through partition walls, bulkheads and existing conduit rather than the slab. We send the scope to your property manager, follow the building's work hours and book the elevator before we start.
Do we have to move out while the house is rewired?
Most families stay. We split the work into phases so the kitchen, a bathroom and the bedrooms aren't without power at the same time. At the end of each day the finished circuits are live and the rest of the house runs as before.
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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