What is the lifespan of electrical wiring?

Electrical wiring doesn't have a single expiration date, but most residential wiring lasts 50–70 years under normal conditions — though the type of wiring, installation quality, and how hard it's been worked all play a major role in how long it actually lasts safely.

Modern copper wiring (NMD-90 cable, the standard since the 1980s) is extremely durable and can last the lifetime of your home when properly installed and not overloaded. The wiring itself rarely "wears out" — problems arise from the insulation degrading, connections loosening over time, or the wiring being pushed beyond its rated capacity. A well-maintained copper system in a 1990s Ottawa home may need nothing more than occasional inspection for decades to come.

Where things get complicated is with older wiring types. Ottawa has a significant number of homes built before 1980 that may contain:

• Knob and tube wiring (pre-1950s): This ungrounded, two-wire system has cloth or rubber insulation that becomes brittle and cracked with age. It was never designed for modern electrical loads and becomes genuinely dangerous when covered with insulation (a common renovation mistake). Most Ottawa insurance companies now refuse to cover homes with active knob and tube, or charge significantly higher premiums.

• Aluminum wiring (roughly 1965–1978): Used during a copper shortage, aluminum wiring expands and contracts differently than copper, causing connections to loosen over time. Loose connections create heat, and heat creates fire risk. It's not a death sentence for your home, but it requires specific remediation — either CO/ALR-rated devices at every outlet or a process called "pigtailing" with approved connectors.

• Early plastic-sheathed wiring (1950s–1970s): The insulation on this era's wiring degrades faster than modern NMD-90 and may be showing its age in older Ottawa homes.

From an Ontario Electrical Safety Code standpoint, there's no mandatory replacement schedule for wiring — but ESA inspectors and insurance underwriters pay close attention to wiring age and type. If you're buying an older Ottawa home, a pre-purchase electrical inspection is one of the smartest investments you can make. An ESA-licensed electrician can assess whether the wiring is safe, insurable, and up to current standards.

Signs your wiring may be past its prime include frequently tripping breakers, flickering lights, outlets that feel warm to the touch, a burning or plastic smell, or discoloration around outlet covers. Any of these warrant an immediate call to a licensed electrician — don't wait.

If your Ottawa home was built before 1975, it's worth having a licensed electrician assess your wiring. Electrical Ottawa offers free consultations to help you understand what you're working with and whether rewiring or remediation makes sense for your situation.