Depends on the situation - generally type 1 SPDs are specified where there is a lightning protection system or overhead lines that act as big aerials. You might consider similar if neighbouring buildings had LPS (connected to the DNO's earth) and you had a separate earthing system.

   - Andy.

Also a lot of professional telcom kit, phone base stations etc, especially things with their own antenna masts etc. already include lighting induced surge protection, but the other way - to protect the outbound cables from the comms equipment.

You may find it is already handled elsewhere.

Ideally chat to the equipment makers and or request installation instructions.

Mike.

As others have said, Type 1 (i.e. combined Type 1+2) required if there is an incoming overhead supply, or the installation (e.g. antenna mast) has a lightning protection system (LPS). However, if an LPS is used, the design and selection of SPDs is covered by BS EN 62305 series and not BS 7671.

mapj1 said:

You may find it is already handled elsewhere.

Well, yes ... and no.

No good providing SPDs on the kit, if it's not on the mains, and vice-versa ... surge protection is required on on all nodes leaving a lightning protection zone (LPZ).

Which is a key point ... see BS EN 50174-3 regarding protection of the telecomms cabling. Requirements for data cabling are not in BS 7671, they are referenced out to BS 6701, which in turn references BS EN 50174 series. Again, there may be different requirements if an LPS is used, see BS EN 62305 series.

Fit type 1 and 2 at parent mains street cabinet.  Then Fit type 3 at the kit.  Some telecoms kit cost thousands of pounds.  It is also worth menting that some Telecoms kit have a built in Type 3 SPD

The main thing to remember is to cascade. 1 then 2 then 3.  Type 1 can take a lot more abuse type 3 less so.

It is also worth looking into what is a Lightning Stike and Lightning Stroke.  Most things while not surive a direct lightling strike but they will survive fron a local strike to a electric pylon.   

Fit type 1 and 2 at parent mains street cabinet.  Then Fit type 3 at the kit.  Some telecoms kit cost thousands of pounds.  It is also worth menting that some Telecoms kit have a built in Type 3 SPD

The main thing to remember is to cascade. 1 then 2 then 3.  Type 1 can take a lot more abuse type 3 less so.

It is also worth looking into what is a Lightning Stike and Lightning Stroke.  Most things while not surive a direct lightling strike but they will survive fron a local strike to a electric pylon.