UK Fire Rating - Rear Knockouts @ Consumer Unit

[LmarshallSparks]

Hello All,

I understand that when cables penetrate a fire-rated wall entering in to a consumer unit, appropriate fire-stopping measures are required to maintain the wall’s fire resistance. However, in scenarios where the consumer unit is mounted with a clearance from the wall, such that the wall’s fire-rated properties remain uncompromised, is it still a regulatory requirement to seal the rear cable entries of the consumer unit with fire-rated materials? Additionally, if sealing is required, what fire-rated materials or methods are typically recommended for this application? Clarification on both points would be greatly appreciated.

 

[Pretty Mouth]

My understanding is it's not necessary unless compromising a fire barrier. Hager instructions:

Cable Access:
Cable access into the metal consumer unit must maintain the integrity of the non-combustable consumer unit so far as reasonably practicable. This can generally be achieved by the installer ensuring that cable access holes they make in the enclosure do not to leave gaps greater than:
· 1.0 mm for the horizontal top surface and
· 2.5 mm for all other surfaces of the enclosure that are accessible after installation.
For rear cable access, the minimum number of knockout(s) shall be removed. Tests on hager consumer units have indicated that there is no specific need for external fire rated cable glands or intumescent sealing in addition to the guidance below, with respect to achieving a non-combustible enclosure. However this does not preclude the designer/installer from using fire rated cable glands or external intumescent sealing should they consider necessary. Internal intumescent pads shall not be used.

https://hager.com/uk/products/pub/media/documentation/00/43/25/ZD0820_D10_D30_CU_ISSUE_6.PDF