Ask the experts/Technical
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Supports for cables in escape routes Changes to the recommendations for fire detectors An introduction to the requirements for auxiliary circuits Changes to electrical installation certificates
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Limiting values of measured earth fault loop impedance Fire protection for electrical equipment in lofts Snags and solutions: A practical guide to everyday electrical problems, now updated to Amendment No 3 of BS 7671
Supports for cables in escape routes There have been a number of instances at times of fire where firefighters have been placed at risk, injured or killed due, in part, to entanglement in cables that have fallen down causing an obstruction. For example, the investigation carried out by Hampshire Fire and Rescue Service into the deaths of two firefighters in 2010, identified one of the factors that led to their deaths as a failure of cable supports. One specific conclusion in the report states: ‘Surface mounted electrical cabling was encased in plastic trunking which failed when exposed to heat, so releasing the cables.’
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vacuating a building in the event of fire should be an unhindered transition; however, it is self-evident that with increasing floor area and/or number of floor levels, a longer evacuation route will generally be created and the potential for hazards along that route increased. Experience has shown that even with adequate evacuation planning (including rehearsal), hazards may be present in an escape route at times of fire, and regardless of the familiarity a building user might have with the particular escape route and building, panic can still occur during the evacuation process, such as, for example, from an unexpected obstacle, such as cables which are dangling and/or have fallen to the floor in the escape route following heat from fire. In addition to flame, fire produces other hot products, such as smoke and gases which will generally rise and circulate in the building and the
Photo courtesy of London Fire Brigade Fire Investigation Team
Plastic trunking melted in a fire and released cables that obstructed escape
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Spring 2015 Connections
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