Knob and Tube Wiring in Older Toronto Homes: A Calm Guide for Buyers
If you’re looking at older houses in Toronto, knob and tube wiring may come up at some point. It can sound more alarming than it needs to, especially the first time you hear the phrase.
Knob and tube is an outdated type of electrical wiring found in older Toronto homes. It doesn’t automatically mean a house is a bad fit. It does mean you’ll want a clear picture of what’s there, what it might mean for insurance, and what it would take to update if the home still feels right.
What knob and tube wiring is
The name is literal. The system uses ceramic knobs to hold wires in place and ceramic tubes to protect them where they pass through wood, like floor joists. The two wires, hot and neutral, run separately rather than being bundled together the way modern wiring is.
Ontario’s Electrical Safety Authority (ESA) notes that this method was used in homes in the early 1900s to 1940s, and it is no longer used in new work. That’s why it still shows up in Toronto’s century homes, sometimes alongside later updates.
It can be easy to assume the whole house was rewired just because the kitchen looks new or the panel has been upgraded. That isn’t always the case. Parts of the original system can remain in attics, basements, or inside walls.
Why insurers and lenders ask about it
This is usually the part that worries buyers most, so it’s worth being precise.
In practice, many insurers won’t cover a home with this wiring, or they’ll add conditions, and lenders need proof of insurance. A problem getting a policy can therefore become a problem getting a mortgage. ESA’s public guidance says the same thing: many insurers will not provide or renew coverage, and some may require replacement first.
There are a few reasons insurers look at this wiring more carefully:
There is no ground wire. Older two-prong outlets don’t give appliances the same path to ground that a modern three-prong outlet does.
The original insulation around the wires can age and become brittle.
The system was not built for today’s electrical loads, with more lighting, kitchen appliances, and electronics than homes used when this wiring was installed.
There can be added risk when the wiring is buried in insulation, which it was not designed for.
Past DIY work can leave risky splices, where newer wiring has been connected in ways that aren’t safe or up to current practice.
None of this means every house with this wiring is unsafe. ESA’s view is that it can be safe when it is properly maintained by a Licensed Electrical Contractor. The concern is less about the original method, and more about age, condition, and whether the system has been altered over the years.
How buyers find out
You usually will not get a complete answer from a quick walk-through. Some of this wiring is visible in an unfinished basement or attic. A lot of it isn’t.
A professional home inspection is the usual first step. The inspector can flag what they can see and access, and recommend a closer look. A home inspection has limits. It is not a full electrical assessment, and inspectors cannot open up walls.
If knob and tube is suspected or confirmed, the next step is a Licensed Electrical Contractor. ESA recommends this specifically, because that visit focuses only on the electrical system. An electrician can check visible conductors for deterioration or damage, look at how the system has been modified, and give you a clearer sense of what, if anything, should be updated.
I always tell buyers to give themselves time for this. It is much easier to make a calm decision when you have both reports in hand.
How to handle it if the house still feels right
Finding this wiring does not have to be the end of the conversation. If the house still fits your needs, the work is to understand the condition, the cost to update, and whether you can get insurance in the meantime.
A few practical steps help:
Keep a home inspection condition in your offer when the situation allows for it, so you have room to learn what’s there before you are committed.
Have a Licensed Electrical Contractor quote the work, and ask whether they are recommending a partial update or a fuller replacement, and why. Electrical work should be done by a Licensed Electrical Contractor, with a notification filed with ESA.
Call an insurance broker early, ideally as soon as you know wiring may be a factor. A broker who is used to older Toronto homes can often find an insurer that will cover the property, sometimes with conditions or a timeline to replace the wiring. I personally have an insurance broker that works with knob and tube wiring.
The cost to update the wiring varies with the size of the house, how much of the original wiring is still in use, and how easy it is to access. I would rather you have a quote for the specific house than a number pulled from someone else’s renovation.
If the house is the right one, and you have a plan for insurance and for the work, this is a project to budget and schedule. It is not automatically a reason to walk away.
What it looks like on streets in Little Portugal and Trinity Bellwoods
This comes up a lot in older parts of the city, including neighbourhoods like Little Portugal and Trinity Bellwoods. Many of the side streets there are lined with Victorian and Edwardian houses, and some of those homes still have original or partially original wiring.
That doesn’t mean every house on those streets has it, and it doesn’t mean a renovated interior is in the clear. Two houses on the same block can be very different. One may have been fully rewired years ago. The one next door may still have original wiring in the attic or basement.
If you’re getting to know these neighbourhoods, I wrote a longer guide to what buyers usually ask about living in Trinity Bellwoods, including the older-home questions that tend to come up. The same habit applies in Little Portugal: look at the specific house, and give the inspection and, if needed, an electrician enough time to do their work.
Happy to talk it through
If you’re looking at an older Toronto home and this is already on your mind, or it comes up during an inspection, I’m happy to talk it through. We can look at what the reports are actually saying, what questions to ask an electrician or an insurance broker, and whether the house still makes sense for you.
No pressure. Just a clear, honest conversation about the house in front of you.
Ashley Smith
Team Lead of the ASP Group
General information only. This is not insurance, legal or electrical advice. Please confirm coverage with a licensed insurance broker, and have any electrical assessment or work done by a Licensed Electrical Contractor. ESA’s public guidance on knob and tube wiring is available at esasafe.com.
