Surge protective devices are frequently sold by lightning protection contractors, and we do not sell them. That is a deliberate position, and it is worth explaining because it occasionally costs us work.
BS EN 62305-4 covers protection of electrical and electronic systems within structures. It treats surge protection as part of a coordinated set of measures: bonding, screening, routing, equipotential bonding at the service entry, and SPDs selected and coordinated across the installation. BS 7671 then imposes its own requirements for surge protection within the electrical installation itself. Both point to the same conclusion. An SPD is a component of the electrical installation, not an accessory to the lightning protection system.
Coordination is the technical reason. Type 1, Type 2 and Type 3 devices have to be selected against the prospective fault current, the earthing arrangement, the let through voltage that the connected equipment can survive and the distances between devices. Getting that right requires the switchgear schedules, the distribution design and the equipment schedules. A specialist contractor who is on site for two weeks to install a roof network has none of that information and no visibility of the boards.
There is a practical reason too. The SPD has to be installed inside the distribution equipment, tested as part of the electrical installation, recorded on the electrical certification and inspected at each fixed wire test. Splitting that responsibility between two contractors creates precisely the gap where nobody replaces the device after it has taken a hit and its indicator has gone red.
So on every design we produce, surge protection is excluded from our scope and written explicitly to the electrical contractor, with the relevant clauses referenced, rather than left silently off the drawing. The client sees that it is required, sees who is responsible for it, and can price it in the right package. On testing contracts we still look at the devices during the annual visit and report any indicator showing end of life, because it costs nothing to look and it is useful to whoever owns the electrical installation.
The general principle is worth applying more widely than SPDs. Where a component belongs in another trade's package, say so clearly at design stage. The awkward conversation early is always cheaper than the missing item found at handover.