Common questions
How often should lightning protection be tested in the UK?
Annually, at intervals of eleven months. Eleven months rather than twelve keeps every certificate inside a twelve month window and moves the test date through the seasons over successive years, so earth resistance is not always measured in the same ground conditions. BS EN 62305-3 sets the maximum permitted intervals by protection class, and the eleven month cycle sits comfortably inside all of them.
How often should a lightning protection system be inspected?
BS EN 62305-3 sets maximum intervals by class. Class I and II systems need a visual inspection every year and a complete inspection every two years. Class III and IV systems need a visual inspection every two years and a complete inspection every four. Structures with a risk of explosion need inspecting more frequently.
Is annual testing a legal requirement?
The law does not name an interval. Regulation 4(2) of the Electricity at Work Regulations 1989 requires the system to be maintained so as to prevent danger, and annual testing is how that duty is normally discharged and evidenced. Insurance requirements are usually what fix the interval at twelve months or less in practice.
When do I need an extra test outside the normal cycle?
After a known or suspected lightning strike on the building. After any work that alters the roof, the elevations or the earthing. After anything is added to the roof that needs bonding in, such as plant, a mast or solar panels. After damage from other trades. And immediately following installation, as initial verification.
What happens if we miss a test?
The system does not stop working, but the record does. That gap is what an insurer sees at renewal or after a claim, and it is what would be examined if an incident occurred. The fix is straightforward: have the system tested, take the current readings as a new baseline, and restart the cycle.
