Is knob and tube wiring in my Saint John home dangerous and does it need replacing?

Knob and Tube Wiring in Saint John Homes — Risks and Replacement

Knob and tube (K&T) wiring is still found in thousands of homes across Saint John, particularly in the uptown, south end, and west side neighbourhoods where many homes date back to the early 1900s. While knob and tube wiring that's in original, unmodified condition isn't inherently dangerous, it's a 100+ year old electrical system that was never designed for modern electrical loads — and that's where the real risk begins.

What Is Knob and Tube Wiring?

Knob and tube was the standard wiring method in New Brunswick homes from about 1890 through the 1940s. It uses individual hot and neutral wires run separately through the house, supported by ceramic "knobs" mounted to joists and passing through ceramic "tubes" where they go through framing members. The wire insulation is typically rubberized cloth that has become brittle with age.

Key characteristics:

• No ground wire — provides no equipment grounding, which means no protection against short circuits to metal appliance cases


• Designed for low loads — original circuits were rated for 15 amps on 14-gauge wire, intended for a few light bulbs per circuit (maybe 200-400 watts total per room)


• Relies on air circulation for heat dissipation — the wires were meant to be exposed to open air in wall and ceiling cavities

When Knob and Tube Becomes Dangerous

Insulation contact is the #1 fire risk. When blown-in or batt insulation is packed around K&T wiring — common in Saint John homes that were insulated during the energy efficiency retrofits of the 1970s-1990s — the wires can't dissipate heat. Under heavy loads, the wire temperature rises, the old rubber insulation degrades faster, and the risk of fire increases significantly. Many house fires attributed to "electrical" causes in older Maritime homes trace back to insulated-over K&T wiring.

Overloaded circuits are nearly universal in K&T homes. A single circuit that was designed to power 3-4 light bulbs in 1920 is now running a TV, computer, phone charger, space heater, and multiple lamps. The wiring heats up beyond its design capacity, especially at connection points.

Amateur modifications are extremely common and extremely dangerous. Over 100+ years, homeowners and handymen have spliced modern Romex wire to K&T conductors, often with nothing more than electrical tape — no junction box, no proper connectors. These hidden splice points are fire hazards.

Degraded insulation is inevitable at this age. The rubberized cloth insulation dries out, cracks, and falls away, leaving bare copper conductors exposed inside wall cavities. Any contact with wood framing, metal pipes, or other wires creates a short circuit risk.

Insurance Implications in New Brunswick

This is often the deciding factor for Saint John homeowners. Most insurance companies in New Brunswick will either refuse to insure a home with active K&T wiring or charge a significant premium. Some insurers require a certified electrical inspection confirming the K&T is safe before issuing a policy, while others won't insure at any price.

If you're buying a home in Saint John with K&T wiring, expect your insurance options to be limited. If you're selling, the buyer's insurance requirements may force a rewire before closing — a significant negotiating point that can affect sale price by $10,000-$20,000.

Does It All Need Replacing?

The Canadian Electrical Code doesn't require you to rip out K&T wiring just because it exists. However, TSANB and the CEC do require that:

• Any new electrical work must use modern wiring methods (NMD90 cable)
• K&T wiring cannot be covered with insulation
• Circuits must not be overloaded beyond their rated capacity
• All connections must be made in approved junction boxes

A practical approach many Saint John homeowners take:

Have a TSANB-licensed electrician inspect the K&T system — Cost: $200-$400 for a thorough inspection. They'll check insulation condition, identify amateur splices, verify circuit loading, and note any contact with building insulation.

Prioritize replacement of high-risk circuits — Kitchen, bathroom, laundry, and any circuit covered by insulation should be rewired first. Cost: $1,500-$3,000 per circuit.

Full rewire when budget allows — A complete rewire of a typical 1,200-1,800 sq ft Saint John home costs $12,000-$25,000, depending on the number of circuits, panel upgrade needs, and how accessible the wiring routes are. Homes with plaster walls (common in older Saint John houses) cost more because fishing new wire through plaster is more difficult than through drywall.

What a Full Rewire Includes

• Removal or disconnection of all K&T wiring
• New 200-amp electrical service and panel ($2,500-$4,500)
• New NMD90 copper wiring throughout the home
• Grounded 3-prong outlets in all locations
• GFCI protection in kitchen, bathroom, laundry, and outdoor locations
• AFCI protection on bedroom circuits (CEC requirement)
• Proper outlet spacing per current CEC (every 1.8 metres along walls)
• TSANB inspection and certificate of compliance
• Typically requires 3-5 days of work for a crew of 2 electricians

The Bottom Line

If your Saint John home has active knob and tube wiring, it's not an emergency that requires immediate action — but it should be on your priority list. Start with a professional inspection to understand the actual condition and risks, address any immediate hazards (exposed wires, insulation contact, overloaded circuits), and plan for a phased or complete rewire within the next few years. The combination of insurance requirements, safety improvements, and increased home value makes rewiring one of the best investments you can make in an older Maritime home.

---

Find a Electrical Contractor

New Brunswick Electrical connects you with experienced contractors through the https://newbrunswickconstructionnetwork.com:

• A+ Solar Solutions ✓
• A&S Electric Ltd. ✓
• Blue Energy Ltd ✓

View all electrical contractors →