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Copper carrying current within its rating does not wear out. Everything around the copper does, and that distinction decides whether you repair or rewire.
Conductors themselves are remarkably durable, and a copper conductor operating within its rating will outlast the building around it. What ages is the insulation that separates conductors, the terminations that join one run to the next, and the devices at the ends. Recognising this changes the rewiring conversation entirely, because it explains the otherwise puzzling situation where a property has wiring in sound condition and still needs substantial work.
Insulation sets the practical service life. Older systems become brittle with age and accumulated heat, and they fail mechanically rather than electrically: the material cracks when the conductor is moved. This produces a characteristic pattern where a property behaves impeccably for decades and then develops faults immediately after somebody works on it, because installing a new device fractured insulation that was intact but fragile. Once a technician confirms that condition in an area, device level work in that area stops being sensible, because each subsequent intervention manufactures a new fault.
The threshold is not age and it is not a number of faults. It is whether the failures are located or distributed. A property with three faults at three identifiable points has three repairs. A property where insulation has become brittle throughout an area has one condition presenting as multiple faults, and repairing them individually is paying repeatedly for a problem that will keep producing new instances.
Testing distinguishes the two straightforwardly. Insulation resistance measurements taken across multiple circuits reveal whether degradation is confined or general. Where readings are sound everywhere except at one point, repair. Where readings are marginal across a whole area, the honest recommendation is replacement of that area, and we would rather say so at the assessment than after you have paid for four separate visits.
Whole property rewiring is disruptive and frequently unnecessary. Most properties are best served by area based replacement sequenced against access opportunities, and the single largest factor in cost is not the length of cable but the route it has to take. Runs through unfinished basements, accessible attic spaces or areas already open for other work cost a fraction of runs through finished, insulated and blocked wall cavities.
This is why the timing conversation matters so much more than owners expect. A rewire scheduled to coincide with other renovation work costs dramatically less than the identical work performed alone, because the access is being opened and finished anyway. Where a property is being worked on for any reason, having the wiring assessed before the walls close is the cheapest opportunity that will exist for years.
No. Age alone is not the criterion. What matters is the condition of the insulation, the terminations and the devices, and that is established by measurement. Plenty of older installations test sound and need only device level attention.
By whether the degradation is located or distributed. Insulation resistance readings across multiple circuits answer this. Sound everywhere except one point means repair. Marginal across an area means that area needs replacing, because individual repairs will keep producing new faults.
In many properties, substantially yes. Routes through basements, attic spaces and existing cavities avoid a great deal of finished surface. The realistic assessment of what can be avoided happens on site, because it depends entirely on the construction.
While walls are already open for other work. The access is the expensive part, and having it opened once for two purposes rather than twice for one is the single largest saving available on this kind of project.
Insulation resistance testing across circuits answers the repair or rewire question with measurements instead of guesswork. Call to arrange an assessment.