A series of experiments to assess the effect of fire on a selection of electrical 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.
There have recently been several recommendations made to UK Government, by HM Coroners and others, regarding falling cables in burning buildings. These recommendations have been made after several incidents where fire-fighters have been trapped by falling cables in burning buildings and this has, in some cases, contributed to fire-fighter fatalities.
BRE Global is aware of three incidents where there have been fire-fighter fatalities as a result of being trapped by falling cables in a burning building. These are:
- Harrow Court, Hertfordshire, 2nd February 2005
- Two fire-fighters and a resident died in a fire in a high-rise block of flats. The fire-fighters were trapped by fallen fire alarm cables prior to an event of abnormal rapid fire development.
- Following an inquest in March 2007, HM Coroner Mr Edward Thomas issued several recommendations through a Rule 43 letter [1, 2] including a recommendation to social housing providers regarding the support of fire alarm cables which should conform (as a minimum) to BS 5839 – Part 1 : 2002; clause 26.2 (f:) .
- Atherstone-on-Stour, Warwickshire, 2nd November 2007
- Four fire-fighters died in a large, highly-insulated warehouse fire.
- It was noted from witness statements that fire-fighters were being caught up in fallen cables during the incident. It is unclear whether the four fatalities were trapped by cables.
- Warwickshire Fire and Rescue Service issued an Operational Bulletin in March 2012 (OB 12/04) regarding “Hanging Cable Hazards from Surface Mounted Conduit and Trunking” as a result of experimental work carried out by BRE Global for the Fire Service . This work confirmed that plastic conduit or trunking surface mounted on ceilings and walls may fail at relatively low temperatures (150°C).
- Shirley Towers, Hampshire, 6th April 2010
- Two fire-fighters died while fighting a fire in a high-rise block of flats after being trapped by fallen cables prior to an event of abnormal rapid fire development.
- Following an inquest in February 2013, HM Coroner Mr K Wiseman issued recommendations in several Rule 43 letters [1, 5] including reiterating the recommendations made by HM Coroner Mr Thomas after the Harrow Court inquest. Mr Wiseman made a further recommendation to have “… Building Regulations amended to ensure ALL [sic] cables, not just fire alarm cables, are supported by fire-resistant cable supports”. Mr Wiseman recommended an “amendment to BS 7671 (2008)…” to achieve this .
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.
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