Knob And Tube Wiring Is Still Common In Canada

Healthy Home, Tales Of Upper Hillsborough

Welcome to my blog on housing, culture, and design, where I explore all the facets of Canadian real estate, housing, and home. I’m Steve Fudge, and I’m a realtor and housing consultant in Toronto, Ontario, Canada. For 30 years! Today I’m writing about oldey-time knob and tube wiring which is still commonly found in vintage dwellings across Canada.

Like so many property owners undertaking upgrades and renovations, when we were transforming The Black House on PEI over a decade ago we were surprised to find old knob and tube wiring throughout parts of our triplex despite the home inspector assuring us all the wiring in the dwelling was ‘upgraded’. Sadly, this isn’t the least bit unusual for owners of vintage homes across Canada. This is because all property inspections are strictly visual and limited only to those building components one can see, and in the case of wiring one basically requires x-ray vision to see what’s behind the old plaster and lath!



Like so many old houses, wiring upgrades to our late 1800s dwelling had been completed piecemeal over the years. In fact, it’s really common to find new wiring located at the electrical panel plus new outlets with attached new wiring in many of the rooms’ walls, but what’s often between these two sets of newer wiring will be old knob and tube wiring tied in between in hidden junction boxes. It’s common and exasperating.



So What Is Knob & Tube Wiring?

Knob and tube wiring was an early standardized method of electrical wiring in buildings constructed from around 1880 through the 1940s. The nickname is derived from the ceramic knobs that are installed to insulate and secure the wiring and the ceramic tubes used to protect the wires where they pass through potentially abrasive materials (primarily wood joists and studs). Unlike subsequent electrical systems where all the wiring is enclosed in a cable, in this system the two wires run separately and only come together at a terminal (switch, receptacle, or junction box).

Furthermore, knob and tube wiring does not provide a third wire for grounding and is therefore considered unsafe in kitchens, washrooms, laundry rooms, and for use outdoors. In other areas, knob and tube wiring that is in good condition with the sheathing intact, property protected from damage, and that haven’t been subjected to extended periods of overloading which can cause it to become brittle, should not pose an increased safety risk. However, over the decades, more and more property insurers will not place an insurance policy on dwellings with knob and tube wiring, citing safety issues regarding the lack of a grounded conduit as the mitigating reason.

Knob and tube wiring became obsolete, not due to any risk, but because of the high cost of installation compared to the invention of electrical cables, which combined both power conductors of a circuit in one run as well as grounding conductors. Furthermore, as an antiquated system, it doesn’t sufficiently meet the electrical requirements of most households today, given our love of electronic gadgets including multiple appliances, home computers, media equipment, and security systems.




A Recent Conditional Sale That Failed To Firm Up

Recently, we conditionally sold a 2-storey semi-detached tenanted dwelling near The Danforth that had been converted into three units, including a basement apartment. The property was not being sold as legally-retrofitted, which meant our Buyer was assuming some risk given it did not comply with Ontario’s Building or Fire Codes. As part of our due diligence, we brought in our trusted home inspector who identified a couple of lines of existing knob and tube wiring.

Although there wasn’t a significant amount of knob and tube wiring, because the property had been converted into 3 units, it still posed some challenges. One insurer said that because it was a 3-dwelling residence all the knob and tube wiring would have to be replaced within 90 days. The property would also have to be inspected by Carson Dunlop Inspections (who is the firm tied to the insurer) in advance or within a week after closing to identify all deficiencies for the insurer. (This is not a bad thing. In fact, we encourage you to invite your insurer into your dwelling shortly after closing to ensure you have appropriate and adequate insurance to protect your investment. Click to read my post  called –> The Importance Of Accurate Homeowner Insurance Coverage). Furthermore, the insurance for a 3-unit dwelling is also more costly that a single-family dwelling with an accessory apartment, being in the range of $3000 to $3500 per year.

It’s important you, as a Buyer, understand all of the risks when purchasing a fully-tenanted older property. Of particular concern is that a new Buyer may be obliged to remedy any deficiencies as soon as possible as they could be compromising the health and safety of the residents. The potential to discover issues such as knob and tube wiring, mold and mildew, asbestos or lead water pipes ranges from possible to probable in the City of Toronto’s (and Canada’s) older housing stock, which means the unsuspecting investor/buyer may find – when they embark on refreshing a recently-vacated suite for example – unwittingly having to do a significant transformation when an issue (like Kitec Plumbing from the 1990s) snowballs into a comprehensive and costly undertaking. Or worse, should you have to replace a major building component like knob and tube wiring (or lead plumbing, etc) to secure property insurance, you could find yourself challenged if, when introducing yourself as the new owner you discover you have disagreeable tenants who do not want to accommodate the disruption that would accompany rewiring a portion of their dwelling (which means cutting holes in the existing walls to feed in new wiring, then patching & repainting). A difficult tenant could not only deny you entry, but they could also request an abatement in their rent or require you to find them alternate accommodations while the work is being completed. Because of these possibilities, as we negotiated the conditional sale our Buyer requested the Seller complete the replacement of the knob and tube wiring by a Master Electrician in advance of the completion date at their own expense to mitigate any potential problem. The Sellers refused, and the conditional sale was collapsed and the Buyer received her deposit back in full without interest or delay, per the Agreement of Purchase & Sale.



Who Insures Knob & Tube Wiring (November 2022)
Here are three companies who currently are willing to insure properties with knob and tube wiring (this list has gotten much shorter over the past decade):

•    TD Insurance: Although they do insure, there are some requirements and questions that need to be answered. As well, TD does not require that the knob and tube wiring be changed within a 30-day timeline, however, they highly recommend that clients switch the wiring for safety reasons. They are best reached online (they have discounts both for online quote and for then buying insurance via a online quote). They also assume the cost of the inspection if Knob & Tube is found.

•.  Square One Home Insurance: Just like TD Insurance, although Square One does insure,  there are some conditions along with a deductible and an underwriter’s approval needed to proceed. For instance, homeowners will need to answer questions regarding a) the age of the house b) its current condition, and c) if there was an inspection done. There is also a deductible of $10K for those houses that do not meet certain requirements.

•  David Slack Insurance Brokers. We really like David Slack. He’s prompt, informed and courteous. Consider contacting him for your insurance needs.




Who Doesn’t Insure Knob & Tube Wiring (November 2022)
While one could assume from the above list that most insurance companies DO NOT insure properties with knob & tube, here are the ones that we contacted who gave us a definitive No:


  • Aviva (through PC Insurance)

  • Aero Insurance

  • The Co-operators

  • Desjardins Insurance Co.

  • Intact Home Insurance

  • Wawanesa Home Insurance

  • Economical Insurance


Discovering knob & tube wiring isn’t ideal, but there are firms who will insure knob & tube wiring – at least temporarily –  and it can be replaced by a certified master electrician who will provide an ESA Certificate of Acceptance from the Electrical Safety Authority on completion. Yes, it takes time, money and effort to resolve, but this is a value-added upgrade that provides peace of mind and safety for all residents, so you’re well-served in making the investment, especially in advance of listing your property for sale.



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Thanks for reading!


– Steve & The Urbaneer Team



The Urbaneer Team

Steven Fudge, Sales Representative
& The Innovative Urbaneer Team
Bosley Real Estate Ltd., Brokerage – (416) 322-8000

– we’re here to earn your trust, then your business –


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