Assessing the effect of fire on electrical cable supports and fixings

BRE Global on behalf of the Department for Communities and Local Government (DCLG) looked at the effect fire has on cable supports and fixings.

BRE Global carries out fire investigation activities on behalf of the Department for Communities and Local Government (DCLG). An important element of this contract with DCLG is to ensure that findings from fire investigations are made available to the fire community, and other stakeholders. In addition to the continued investigative work carried out by BRE Global, the latest contract includes an element of experimental work to allow further analysis of issues arising from investigations of incidents.

Key findings

There is a need for careful consideration in the selection of fixings for any cable support and based on these findings.
Wherever possible, fixings which will maintain their mechanical strength when exposed to temperatures greater than 600°C should be used if the risk of failure of the support is to be avoided.
This programme of work demonstrated that there are commercially-available fixings capable of withstanding up to 400°C.
It is possible to use combustible conduit and cable management systems however they need to be installed with non-combustible supports and fixings which can maintain mechanical strength when exposed to temperatures greater than 600°C to prevent cables from dropping down.

More details about the findings are contained with the report.

Report summary

The overall aim of this project was to assess the ability of a selection of commercially available cable supports for electrical installations to maintain their integrity and hold electrical cabling in place when exposed to temperatures typically encountered in compartment fires. A second series of experiments was carried out to assess the performance of a range of commercially available fixings for cable supports in concrete substrates when exposed to elevated temperatures. The findings of the experiments are intended to inform DCLG Building Regulations and Standards Division about the installation of cables in buildings.

This experimental work was not intended as a comprehensive testing programme of individual products but rather as a “proof of concept” and to demonstrate a possible simple solution to the issues which have been raised.