An updated version of BS9991 has been published on 27th November 2024. The new BS9991:2024 includes requirements for services running horizontally within common access corridors.

Section 27.2.2 states: 

Where services are run horizontally within common access corridors and lobbies, including corridor access for firefighting shafts, they should be either enclosed with fire-resisting construction or meet all of the following criteria: 

a) The exposed surface of the material/product used is class B-s3,d2 or better;

b) The supports and fixings in the cavity are class A1;

c) any pipe insulation system is class B-s3,d2 or better; and

d) any electrical wiring in the cavity is laid in metal trays or metal conduit. 

From an electrical perspective the items requiring compliance are a,b and d.

b and d are simple to comply with however item a appears to be very difficult given the cable products commercially available.

The following services are available as B2ca - Cat6 data cables, Optical cables, co-axial TV cables, SWA cables.

Flat twin (FT&E) cables in LSOH form only appear to accord to Dca.  There doesn't seem to be flex cables that are better than Dca either. So we can use steel conduit to wire all the small power and lighting in the common corridors, this is quite a price hike. However, wiring from the conduit system to the luminaires in flexible cable doesn't appear possible. 

A further complication is that fire rated cables such as FP200 or FP600 are not currently covered by the CPR Euro class rating. Therefore we do not know if they will accord to B2ca or better. 

I have spoken with Prysmian cables, and there were not able to provide me with details of any cables suitable for wiring small power or lighting that would accord with B2ca or better. 

I would be very interested to hear from fellow engineers, their point of view on the new BS9991:2024 and how to comply with the new requirements.