Knob and Tube Wiring in Kingston: What You Need to Know Before Buying an Older Home

Knob and tube wiring was the standard method of electrical wiring in North American homes from about 1880 to 1950. It uses ceramic knobs to hold wires along joists and ceramic tubes to pass wires through structural members. The wires themselves are single-conductor, rubber-insulated copper. While K&T wiring was considered safe when it was installed, it was designed for a fraction of the electrical load that modern homes demand.

K&T wiring isn't inherently dangerous if it's in perfect condition and hasn't been modified. The problem is that after 75–100+ years, the rubber insulation becomes brittle and cracks, exposing bare copper wire. This creates a serious fire risk. K&T wiring also lacks a ground wire, meaning there's no protection against electrical faults. Add in decades of DIY modifications, blown-in insulation covering the wires (a major fire hazard), and increased electrical demand, and you've got a recipe for trouble.

Many insurance companies in Ontario will not insure a home with active knob and tube wiring, or they'll charge significantly higher premiums. If you're buying a home with K&T, your insurance company will likely require a full electrical inspection and may insist on rewiring before they'll issue a policy. This is something to factor into your purchase negotiations.

Replacing K&T wiring in a Kingston home typically costs between $8,000 and $20,000, depending on the size of the home, the number of circuits, and the accessibility of the wiring. A small bungalow with an open basement and attic will be on the lower end, while a large two-storey Victorian with plaster walls and limited access will be at the higher end. The cost includes new NMD90 copper wiring, a panel upgrade (if needed), new outlets and switches, and the ESA permit and inspection.

In some cases, yes. If the K&T wiring is only present in certain areas of the home (for example, only the second floor), you may be able to rewire just those sections. However, many insurance companies require a full replacement before they'll provide coverage. We can assess your specific situation and provide a detailed quote.

If you're viewing older homes in Kingston, look for signs of K&T wiring: two-prong outlets (no ground), round or push-button light switches, visible ceramic knobs in the basement or attic, and fuse boxes instead of breaker panels. A professional electrical inspection before closing is always a smart investment — it could save you thousands in unexpected repairs.