Is It Safe to Live in a House with Old Wiring?
Is It Safe to Live in a House with Old Wiring?
The safety of a house with old wiring depends on what type of wiring is present, its condition, and whether it has been properly maintained. Some older wiring types present significant fire and shock hazards; others remain safe if undamaged and not overloaded.
Common Old Wiring Types in Ontario Homes
- Knob-and-tube (pre-1950s): Individual conductors run on ceramic knobs and through tubes at framing members. No ground conductor. Insulation is rubber and cloth — brittle and cracked with age. Cannot be covered with attic insulation. Many Ontario insurers will not cover homes with active knob-and-tube wiring, or they charge significant surcharges
- Aluminum branch circuit wiring (1960s–1970s): Single-strand aluminum conductors in NMD cable. Aluminum expands and contracts more than copper, loosening connections over time — a significant fire hazard unless all connections and devices are rated for aluminum (marked AL or CO/ALR). Requires inspection and remediation at every termination point
- Older NMD-2/NMD-7 cable: Earlier versions of NMD cable with 60°C-rated insulation instead of the current 90°C — may be fine if loads are within its rating, but cannot support the same load as NMD-90
- Two-wire circuits (no ground): Wiring with only a hot and neutral — no equipment ground. Safe if undamaged but cannot support three-prong devices or modern GFCI requirements without upgrades
When to Upgrade
If your home has knob-and-tube or aluminum branch circuit wiring, have it inspected by a licensed electrician before assuming it is safe. Insurance often requires remediation before coverage is granted or renewed. EZSMART inspects and upgrades old wiring across Ontario, from knob-and-tube replacement to aluminum remediation. Contact us for an assessment.
Amir Azimipour
Electrician Since 2008
Journeyman Electrician
Designated Master Electrician at EZSMART Corp
