Complete guide to identifying, assessing, and replacing knob and tube wiring in Ontario homes. Covers insurance implications, costs, and the replacement process.
Written by licensed electricians • ECRA/ESA #7000102
Updated May 22, 2026
PDF • 14-18 pages
By O. MOREAL ELECTRIC
Knob and tube wiring, common in homes built before 1950, poses significant safety risks and can affect your ability to get home insurance. Our comprehensive replacement guide helps Ontario homeowners identify knob and tube wiring, understand the risks, navigate insurance requirements, and plan for replacement. With detailed cost estimates, process walkthroughs, and guidance on choosing a qualified contractor, this guide gives you everything needed to make informed decisions about your home's electrical safety.
Have a licensed electrical contractor inspect your home to confirm the presence and condition of knob and tube wiring. They'll assess the scope of work needed and provide a detailed quote.
Your licensed contractor will file the necessary Notification of Intent with the Electrical Safety Authority. Never proceed with electrical work without proper permits.
Work with your contractor to plan the new wiring routes. Decide between a complete rewire or a phased approach based on your budget and the condition of existing wiring.
The contractor will replace knob and tube circuits with modern NM (Romex) or AC (BX) cable, install proper grounding, and update outlets and switches to current code requirements.
After replacement, an ESA inspector will verify the work meets the Ontario Electrical Safety Code. Upon passing, you'll receive a Certificate of Acceptance — essential for insurance purposes.
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