Knob-and-Tube Wiring in Ontario
Knob-and-tube was used in Ontario homes from the early 1900s to the 1940s and is no longer used. The Electrical Safety Authority (ESA) says it is safe provided it is properly maintained by a Licensed Electrical Contractor, but older systems do not have the safety benefits of modern wiring, and many insurers will not provide or renew coverage on homes that have it. ESA recommends having a Licensed Electrical Contractor assess the electrical system.
What is knob-and-tube wiring?
Knob-and-tube is an older wiring method. ESA states it was used in homes in the early 1900s to the 1940s and is no longer used.
The Ontario Electrical Safety Code (28th Edition, 2021) removed the installation rules for knob-and-tube wiring. ESA notes that the Code is not retroactive.
Is knob-and-tube wiring automatically unsafe?
No. ESA states that knob-and-tube wiring is safe provided it is properly maintained by a Licensed Electrical Contractor.
ESA also points out that these older systems do not have the same safety benefits as modern ones. As one example, ESA notes that ground fault circuit interrupters make wet locations such as bathrooms and outdoor areas safer.
Why homeowners have it assessed
Homeowners commonly have older wiring assessed for these reasons:
- —To check the condition of the wiring for deterioration or damage
- —Because an insurer may restrict, decline or require changes before providing coverage
- —To plan around modern safety features the original wiring does not have
Does it always need to be completely replaced?
Not automatically. An assessment shows the condition of the wiring and what the project needs. ESA states that a Licensed Electrical Contractor may recommend replacing the wiring to ensure your safety.
Insurance can also drive the decision. ESA notes that some insurers may require replacement of knob-and-tube wiring before they provide coverage, so it is worth asking your insurer what it requires.
Buying or renovating a home with older wiring
ESA notes that an assessment by a Licensed Electrical Contractor is different from a home inspection because it focuses only on the electrical system. If you are buying or renovating, having the electrical system assessed before you commit to a plan helps you understand what the work may involve.
Rewiring and other electrical work in Ontario generally requires an ESA notification of work. Our guide to electrical permits and ESA notifications explains how that works.
What an electrical assessment can determine
According to ESA, the contractor can check the knob-and-tube conductors for signs of deterioration or damage and may recommend replacing the wiring. The result is a clearer picture of what, if anything, needs to be done.
Need older wiring assessed?
Knob and tube rewiring is part of our residential electrical services. For related repairs and upgrades, see electrical service and repairs. We serve Rockwood and Fergus, along with the other communities on our service areas page.
Sources and further reading
This guide summarizes information published by the Electrical Safety Authority. It is general information, not advice about your specific property.
Need older wiring assessed?
Tell us about the home and what you are planning, and we will follow up on the next steps.