How Long Does Romex Wiring Last?

How Long Does Romex Wiring Last?

Romex (non-metallic sheathed cable, or NM cable) is designed to last the lifetime of the building when installed correctly and not subjected to physical damage. The copper conductors themselves do not degrade under normal conditions. What does age is the plastic insulation and jacket — modern Romex uses PVC insulation rated for decades of service, but older wiring from the 1950s through 1970s used different insulation materials that can become brittle over time. The wire itself is not the concern; it is the insulation condition and any damage from heat, rodents, or improper installation that determines when wiring needs replacement.

Signs That Wiring May Need Attention

• Insulation that is cracked, brittle, or crumbling when touched — common in wiring from the 1950s and 1960s
• Cloth-wrapped insulation (older than typical PVC), especially if the cloth is frayed
• Discolouration or scorch marks near outlets, switches, or the panel
• Wiring that runs through areas with consistently high heat (near recessed lights, near HVAC equipment)
• Knob-and-tube wiring, which has no ground conductor and uses rubber insulation that degrades

When Rewiring Is Warranted

Rewiring is warranted when insulation is visibly degraded, when the existing wiring cannot safely support modern electrical loads, or when adding circuits would require significant disturbance of old wiring anyway. A full rewire is also recommended when knob-and-tube wiring is present, when the panel is being upgraded, or when renovations open walls throughout the home. A Licensed Electrical Contractor can assess the condition of existing wiring and advise on whether targeted repair or full replacement is the appropriate approach.

EZSMART performs wiring assessments and rewiring projects across Ontario. Contact us if you are concerned about the condition of the wiring in your home.

Amir Azimipour

Electrician Since 2008 Journeyman Electrician Designated Master Electrician at EZSMART Corp