Key takeaways
- Knob and tube wiring is common in homes built before about 1950, and aluminum branch wiring in many homes from the late 1960s and 1970s.
- Both can be safe if in good condition and properly connected, but both have known weak points.
- Many insurers ask about older wiring. An electrician's assessment tells you exactly what you have.
Niagara has plenty of older homes, especially in St. Catharines, Niagara Falls, Welland and the older parts of every town. Many of them still have original wiring. Two types come up often: knob and tube, and aluminum branch circuit wiring.
Knob and tube wiring
Knob and tube was the standard in homes built before about 1950. Wires run separately through ceramic knobs and tubes, with no ground wire. In an attic or unfinished basement you may see single wires supported on white ceramic knobs.
The concerns: the insulation is old and can become brittle, there is no ground for modern devices, and decades of renovations have often left splices and additions that were never done properly. Knob and tube was also designed to shed heat into open air, so insulation blown over it can cause problems.
Aluminum branch wiring
Aluminum wiring was used in many homes built in the late 1960s and 1970s. You may see "AL" or "ALUMINUM" printed on the cable jacket in the basement or at the panel.
The concerns: aluminum expands and contracts more than copper and oxidizes at connections. Over time, connections at outlets, switches and fixtures can loosen and overheat, especially with devices not rated for aluminum.
Is it dangerous?
Not automatically. Wiring in good condition with proper connections can perform safely. The risk comes from age, damage, overloading and poor connections. The only way to know is an inspection by a licensed electrician.
Insurance
Many insurers ask whether a home has knob and tube or aluminum wiring, and some require an electrician's assessment or remediation before they will provide or renew coverage. Talk to your insurer about what they need.
Your options
- Assessment. We inspect the wiring and panel and tell you what we find.
- Targeted repairs. For aluminum wiring, connections can be remediated with devices and connectors approved for aluminum.
- Partial or full replacement. Rewiring room by room, often timed with renovations when walls are already open.
- Panel upgrade. Older homes often need a panel or service upgrade at the same time.
FM Electric assesses and updates older wiring across Niagara. See our residential electrical and renovation wiring services, or call (905) 931-4522.
Frequently asked questions
How do I know if my house has knob and tube wiring?
Look in the attic or unfinished basement for single wires running on ceramic knobs or through ceramic tubes. Two-prong outlets throughout the house are another hint. An electrician can confirm.
Can I get insurance with knob and tube wiring in Ontario?
It depends on the insurer. Many ask for an electrician's assessment and some require replacement. Check with your insurance provider.
