Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • Replies 1 reply
  • Subscribers 17 subscribers
  • Views 585 views
  • Users 0 members are here
Options
You may also be interested in

BS9991:2024 - Section 27.2.2 - Services running horizontally

John Samways

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. 

Parents

  • Hi John,

    Brain dump ...

    I have been struggling with the same issue.  The CPR Class Bca requirement appears quite stringent regards a cable's flame propagation requirements.  Putting aside the Smoke, Droplet and Gas considerations; and as an observation only, sheathed and insulated flexible power cables, like twin & earth; appear to be tested to BS EN 60332-1-2 but not the more onerous BS EN 60332-3.

    The CPR Class Bca clearly has a more onerous testing compared to Cca and below, but I don't know if this additional testing is defined in BS EN 60332-1-2 or forms part of a separate test requirement defined in BS EN 60332-3 or some other standard.

    I'd suggest that this difference of testing standard is the step between a Cca (and below) and a cable that might be considered class Bca.

     

    For the purposes of this post 'exposed' is a cable installed on non combustible (CPR class A) cable containment system and not housed in fire resistant partition.

    BS 9991 27.2.2.requires exposed cables to be CPR Class Bca or better:

    In order to comply with BS 9991 27.2.2. i don't see how an exposed cable failing to achieve class Bca could be deemed acceptable in any HRB corridor without the acknowledgement and acceptance of the client, fire engineer, and presumably; the insurer.

    BS 7671 422.2.1 requires an exposed cable in protected demise to achieve BS EN 60332-3.

    In order to comply with BS 7671 422.2.1 i don't see how an exposed cable failing to achieve BS EN 60332-3 could be deemed acceptable in any 'protected' demise without the acknowledgement and acceptance of the client, fire engineer, and presumably; the insurer.

    In both instances a 'twin and earth' cable would be deemed unsuitable since it has CPR class Cca or below and does not achieve BS 60332-3.

    The apparent exclusion of 'fire resisting' cabling from the CPR for cables is an interesting one and remains unresolved since 2012 I believe.

    As a side note, all fire resistant cables appear to achieve BS EN 60332-3.

    -

    In answer to your original query regards complying with BS 9991, the standard is clearly attempting to create a fire sterile environment by adopting materials with zero or low combustibility.  In this vein, a class Cca or lower cable presents an avoidable risk of flame propagation.

    Since fire resistant cables are presently excluded from the CPR Class system; you might consider this to mean that any 'fire resistant' cable would be acceptable.  Since such a cable is likely compliant with BS 60332-3 you might argue such cable would perform to an equivalent standard of that of a CPR Class Bca cable.  Since this is a departure from the standard, this cable type should be acknowledged and approved by client, fire engineer, insure etc.

    Let me know what you think.

Reply

  • Hi John,

    Brain dump ...

    I have been struggling with the same issue.  The CPR Class Bca requirement appears quite stringent regards a cable's flame propagation requirements.  Putting aside the Smoke, Droplet and Gas considerations; and as an observation only, sheathed and insulated flexible power cables, like twin & earth; appear to be tested to BS EN 60332-1-2 but not the more onerous BS EN 60332-3.

    The CPR Class Bca clearly has a more onerous testing compared to Cca and below, but I don't know if this additional testing is defined in BS EN 60332-1-2 or forms part of a separate test requirement defined in BS EN 60332-3 or some other standard.

    I'd suggest that this difference of testing standard is the step between a Cca (and below) and a cable that might be considered class Bca.

     

    For the purposes of this post 'exposed' is a cable installed on non combustible (CPR class A) cable containment system and not housed in fire resistant partition.

    BS 9991 27.2.2.requires exposed cables to be CPR Class Bca or better:

    In order to comply with BS 9991 27.2.2. i don't see how an exposed cable failing to achieve class Bca could be deemed acceptable in any HRB corridor without the acknowledgement and acceptance of the client, fire engineer, and presumably; the insurer.

    BS 7671 422.2.1 requires an exposed cable in protected demise to achieve BS EN 60332-3.

    In order to comply with BS 7671 422.2.1 i don't see how an exposed cable failing to achieve BS EN 60332-3 could be deemed acceptable in any 'protected' demise without the acknowledgement and acceptance of the client, fire engineer, and presumably; the insurer.

    In both instances a 'twin and earth' cable would be deemed unsuitable since it has CPR class Cca or below and does not achieve BS 60332-3.

    The apparent exclusion of 'fire resisting' cabling from the CPR for cables is an interesting one and remains unresolved since 2012 I believe.

    As a side note, all fire resistant cables appear to achieve BS EN 60332-3.

    -

    In answer to your original query regards complying with BS 9991, the standard is clearly attempting to create a fire sterile environment by adopting materials with zero or low combustibility.  In this vein, a class Cca or lower cable presents an avoidable risk of flame propagation.

    Since fire resistant cables are presently excluded from the CPR Class system; you might consider this to mean that any 'fire resistant' cable would be acceptable.  Since such a cable is likely compliant with BS 60332-3 you might argue such cable would perform to an equivalent standard of that of a CPR Class Bca cable.  Since this is a departure from the standard, this cable type should be acknowledged and approved by client, fire engineer, insure etc.

    Let me know what you think.

Children
No Data

Community Rules & Guidelines