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Knob-and-Tube and Aluminum Wiring: Safety and Insurance
What older wiring means for safety, insurance and your upgrade options.
Older Canadian homes can have wiring that was standard when it went in but raises questions today. If you're buying an older home or renewing insurance, you may be asked about it.
Knob-and-tube
Single wires run on ceramic knobs and through ceramic tubes, with no ground. Insulation can become brittle, and later renovations sometimes buried it under insulation, which it wasn't designed for.
Many insurers want it removed or certified. Replacement usually means rewiring the affected circuits.
Aluminum branch wiring
Aluminum expands and oxidises differently from copper, which can loosen connections at outlets and switches. Warm cover plates, flickering lights or a burning smell are warning signs.
An electrician can often repair connections with approved methods such as connectors rated for aluminum-to-copper, instead of rewiring the house.
What an electrical inspection covers
- Type and condition of wiring
- Panel condition and capacity
- Grounding and bonding
- Outlets, switches and connections
- Evidence of overheating
Working with insurers
Ask your insurer exactly what they need, such as an electrician's letter or a provincial inspection certificate. Get that in writing before you start work.
Common questions
Existing installations aren't necessarily illegal, but insurers may limit coverage.
Check exposed wiring in the basement or attic, or have an electrician inspect.
Electricians fish wire through walls where possible, with small openings that are patched afterwards.