Knob-and-tube replacement · Toronto & GTA
Knob-and-tube wiring replacement in Toronto and the GTA
Your insurer wants it gone, or a home inspector flagged it on a house you're buying. We start with a full electrical inspection to find every live run, fix anything urgent, then replace the old circuits with new grounded wiring under an ESA permit.
What it is
How to recognize knob-and-tube wiring
Knob-and-tube was the standard way to wire a house in Ontario until around 1950. Instead of one cable holding all the conductors, it runs two separate wires, a hot and a neutral, each held away from the wood on white porcelain knobs and passed through holes in the joists inside porcelain tubes.
You can often spot it yourself. Look up at the joists in an unfinished basement or across the attic floor: single cloth-covered wires spaced a few inches apart, clipped to porcelain spools, are the giveaway. Two-prong outlets, ceiling lights on pull chains and a fuse box are other clues, though none of them proves it on its own.
Plenty of houses in Toronto, Forest Hill and the older parts of Etobicoke were built while it was in use. Many have been partly rewired since, which is why a house can look modern at the panel and still hide old runs to an upstairs bedroom.
Why it matters now
Insurance, age and the way houses changed around it
Knob-and-tube wasn't badly designed for its time. The trouble is what nearly a century of use, renovations and modern appliances have done to it.
| Knob-and-tube | Modern grounded cable | |
|---|---|---|
| Ground wire | None | Yes, at every outlet and fixture |
| Insulation | Cloth and rubber, often brittle with age | Thermoplastic, in a sheathed cable |
| Heat | Built to shed heat into open air, so it shouldn't be buried in insulation | Rated to run inside insulated walls |
| Circuit capacity | Wired for lights and a few small appliances | Sized for today's kitchens, laundry and electronics |
| Insurance | Many insurers ask about it, refuse it or add conditions | No questions asked about the wiring type |
The biggest risks we see are rarely the original wiring itself. They're the splices, extensions and overfused circuits added to it over the decades.
Our approach
Inspection first, then replacement
Insurers and homeowners both call us for this work, and every job starts the same way: a full home electrical inspection. We trace which circuits are still knob-and-tube, which have been extended with newer cable, and whether anything is damaged, overheating or covered by insulation. Anything that needs immediate attention is dealt with first.
Then we replace the old runs with new grounded copper wiring, built to the current Ontario Electrical Safety Code and inspected by ESA. Each old circuit is disconnected at the panel and made dead, so it can never be energized again. Where the new circuits need more breaker space or capacity, we tell you whether a panel upgrade should go in at the same time.
Most families stay in the house while we work. We plan the order of rooms with you so bedrooms, the kitchen and the fridge have power at the end of each day.
- Full home electrical inspectionEvery live knob-and-tube run found and recorded
- Urgent fixes firstDamaged or overheating circuits made safe
- New grounded circuitsCopper cable fished through walls and ceilings
- Old wiring disconnectedMade dead at the panel so it can't be reused
- ESA permit and inspectionCertificate of Acceptance for your insurer
Cost factors
What changes the price of knob-and-tube replacement
We don't publish prices because two houses of the same age can be very different jobs. You get a fixed, written price after the inspection. These are the things that move it:
- How much is left. Two leftover circuits cost far less than a house that still runs mostly on the original wiring.
- Access. An unfinished basement and an open attic make fishing new cable much quicker than finished ceilings on every floor.
- Plaster walls. Plaster and lath take more care to open and patch than drywall.
- The panel. A fuse box or a full panel may need replacing to take the new circuits.
- Patching and painting. Included or left to your own trades, as you prefer.
How it works
How a knob-and-tube replacement runs
Inspection
We find every remaining run and check its condition.
Urgent fixes
Anything unsafe is made safe straight away.
Plan and price
Routes, phases, openings and a fixed written price.
Permit and rewire
We file with ESA and run the new circuits room by room.
ESA inspection
The work passes, and you get the certificate for your insurer.
Questions
Knob-and-tube replacement: common questions
Does knob-and-tube have to be replaced?
Ontario's electrical rules don't require you to remove knob-and-tube that is in good condition and hasn't been tampered with. The pressure usually comes from insurers, many of whom won't cover a house with it in use, or will only cover it once it's replaced. Its age is the other reason: the insulation on wire this old is often brittle, and it has no ground. Our inspection tells you what condition yours is in and whether any of it needs attention right away.
Can I replace knob-and-tube myself?
Ontario does let homeowners take out their own ESA permit for some work in a house they own and live in. Replacing knob-and-tube is a hard first project, though: the old runs are often live, hidden behind plaster and spliced into newer wiring. Anyone you pay to do electrical work must hold an ECRA/ESA licence, which you can check on ESA's website.
How long does knob-and-tube replacement take?
It depends on how much is left and how easy the walls are to reach. A few remaining circuits in an open basement can take a day or two. A whole three-storey house with plaster walls takes much longer and is usually done room by room. You get a schedule with the written quote.
Will you need to open my plaster walls?
Some small openings, yes, but not wholesale demolition. We pull new cable from the basement and the attic wherever we can, and cut neat access holes only where a run can't be fished. We tell you where those openings will be before we start.
What do I give my insurer afterwards?
The work is done under an ESA permit, so when it passes inspection you get ESA's Certificate of Acceptance. We also put in writing which circuits were replaced and that the old wiring was disconnected. Ask your insurer what they need before we start, so the paperwork matches.
Are you licensed and insured?
Yes. Marrast Contracting is a Licensed Electrical Contractor, licence ECRA/ESA 7016430, and every job is led by Shaldin Marrast, a Master Electrician. You can check our licence on the Electrical Safety Authority's contractor lookup at esasafe.com.
To price your job, send us
- The address and the age of the home
- What your insurer or home inspector told you, and any deadline
- Photos of the panel and any wiring you can see in the basement or attic
- Which floors are finished, and whether the walls are plaster or drywall
Where we work
Knob-and-tube replacement across the GTA
We serve homeowners, builders and businesses across Toronto and the GTA.
- North York
- Toronto
- Forest Hill
- Etobicoke
- Scarborough
- Mississauga
- Vaughan
- Richmond Hill
- Oakville
- Caledon
- King
- Barrie
- Markham
- Aurora
- Newmarket
- Brampton
- Alliston
- Wasaga Beach
- Collingwood