How often should lightning protection be tested?

The question sounds simple, but the answer depends on who you ask. The standard gives one set of figures, government guidance for schools another, and church insurers a third. Here is how they fit together, and what interval is sensible for your building.

What BS EN 62305 says

BS EN 62305-3, the part of the standard covering lightning protection systems, sets the longest a system may go between inspections. It depends on the class of system, which is fixed by the risk assessment when the system is designed.

A visual inspection checks the system for damage, corrosion and changes to the building. A complete inspection adds the electrical tests: continuity from roof to ground and the resistance of each earth.

Critical situations include structures with sensitive internal systems, office blocks, commercial buildings, and places where many people may be present. Structures with an explosion risk need a visual check every six months and electrical testing every year.

Why most buildings test every year

Put those categories together and very few occupied buildings escape the yearly column. Offices are named. Schools, hospitals, care homes, shops and places of worship are places where many people gather. Almost every modern building has sensitive electronic systems.

Government guidance points the same way. The Department for Education’s estate management guidance says the British Standard recommends that all lightning protection systems are inspected and tested at least annually, and schools follow that.

Many specialists go further and test every 11 months. Historic England notes that some members of ATLAS, the trade body, advise this interval. The reason is the earth readings: dry summer ground reads higher than wet winter ground, and moving the test a month each year builds up readings across the seasons.

Churches and historic buildings

Advice for churches varies more:

• Some dioceses advise annual inspection.
• The Diocese of Chester suggests every two and a half years.
• Methodist Insurance says every two and a half or four years depending on the system installed.

The safest course is to follow your own insurer’s conditions and your diocese, and to test sooner if anything changes.

When to test early

Do not wait for the next date if:

• the building may have been struck, or there was a strike close by;
• tape, clips or test clamps have been stolen or damaged;
• roofers, scaffolders or other trades have worked near the system;
• plant, aerials, solar panels or an extension have been added;
• ground works have been done near the earth pits;
• a repair has been carried out, which should always be followed by a test.

Historic England recommends a full inspection and test after installation, repairs and modifications.

What the interval means for the report

The interval also shapes what you should expect to see on paper. A certificate from a yearly test should give the readings for every earth and continuity path, compare them with last year, list any defects in order of priority, and state the next due date. If the system was designed to a particular class, the report should say so; if nobody knows the class, ask the tester to record what the layout suggests, because that tells you which row of the table above applies.

A visual check between full tests is cheap insurance on busy or exposed buildings. Site staff can do a simple walk round after storms, looking for tape hanging off the wall, missing sections at low level, broken test clamp covers and lids lifted off earth pits, and report anything unusual. It does not replace the specialist test, but it catches theft and storm damage months earlier.

Who checks that it has been done

In a school, governors and the trust estates team usually see the certificate as part of the compliance return. In a church, it goes in the log book and the quinquennial inspector will ask for it. For commercial buildings, insurers and auditors may ask at renewal. Keep certificates together, because a run of past readings is far more useful than a single year’s.

Keeping track

The certificate from each test should state the next due date. Put it in the compliance calendar alongside fire alarm, emergency lighting and electrical testing. If you look after several buildings, a single contract covering them all usually costs less per building than separate visits, and our cost planner will give you a budget.

To understand what happens on the day, read our page on lightning protection testing and inspection. If your system is due or overdue, use the form below and we will find a specialist who covers your area.