How long does a lightning protection system last

A lightning protection system lasts 20 to 30 years, and unlike most components its age tells you almost nothing. The rods, conductors, and earth connections can look intact while no longer doing their job, because the way this system fails is invisible: corrosion at a joint, a loosened connection, an earth resistance that has drifted out of range. Its whole value rests on a periodic inspection, not on the calendar, which is why the inspection is the real clock here.

What it lasts

Component	Typical lifespan	What usually ends it
Lightning protection system	20–30 years	corrosion, connection degradation, earth resistance drift

This range comes from lightning-protection trade data behind the planning model, held at medium-high confidence, and it applies only to the houses that have such a system, typically taller or exposed properties and those where one was required. The number is best read as the interval over which the metalwork and earthing degrade enough to need renewal, assuming it is inspected along the way. Left uninspected for its whole life, a system can reach the end of that range having quietly stopped protecting years earlier, with nothing visible to say so.

It fails where you cannot see it

A lightning protection system does not wear out in the open the way a roof covering does; it degrades at its connections and in the ground. A down-conductor joint corrodes and loses continuity; a clamp works loose; the earth electrode’s resistance climbs as the ground and the connection age, until a strike can no longer be carried safely away. None of that shows from the ground, and none of it announces itself. This is the defining feature of the component: its condition and its appearance are unrelated, so the only way to know it still works is to test it. Age is a prompt to inspect, not a measure of whether it is still doing its job.

The inspection is the maintenance

For most components maintenance is a set of tasks; for lightning protection it is essentially one, the periodic test. On a cycle commonly around every five years, a competent installer checks the continuity of the conductors, the condition of the joints and clamps, and above all the earth resistance, which is the number that decides whether the system can still do its work. A test that passes confirms the system for another cycle; a test that flags high earth resistance or a corroded joint identifies a specific repair, usually a re-bond, a new clamp, or work on the earth electrode, long before the whole system needs renewing. Skipping the test does not save money; it removes the only evidence the system still functions.

When to plan renewal

Felix’s house on an exposed hillside near Stuttgart has a lightning protection system installed in 1999, twenty-seven years into a 20-to-30-year range, and it has never had a problem, mostly because it has never been tested. That is the risk, not the reassurance. He books an inspection. If the conductors and earth pass, the system is confirmed and he plans a renewal toward the end of its range; if the earth resistance has drifted or a joint has corroded, he has found a silent failure while it is still a repair rather than a discovery made the hard way. Either result is worth having, which is exactly why age alone was never the answer.

What this means before you call anyone

Lightning protection is the clearest case of a component you manage by inspection date, not by age, because age and condition are disconnected. The discipline is short: keep the test cycle, act on what it flags, and plan renewal toward the end of the range once a test confirms the system is near it. In appkeep the system’s age sits alongside the date of its last inspection, so the next test is booked before the interval lapses and a system that looks fine is known to work. The corrective-versus-preventive-maintenance guide covers why a scheduled test beats waiting for the storm to reveal the fault.