2008-05-30
Any emergency lighting or fire detection and alarm system is only as good as the installation of the cabling. So, it is critically important for installers to follow the manufacturer’s guidelines, because if a cable fails to perform in an emergency, no amount of system sophistication or technology will make up for the loss of power to luminaires, detectors or control panels.
The company contends that correct fixing method, fixing spacing, bending and jointing of cables is a vital part of any installation, as every part of a cable system’s critical signal path must resist the effects of fire.
“Cable manufacturer’s recommendations must be treated as compulsory, and not merely an indication of best practice,” says Marketing Services Manager, Mark Froggatt.
“Ignoring the manufacturer’s guidelines may well put at risk the level of fire survival. Should the cabling fail in a fire as a result of poor installation, it will certainly put the installer in an extremely uncomfortable position following the introduction of the Regulator Reform (Fire Safety) Order.”
He continued: “The correct securing of cables is a vital part of any installation. You might think this is obvious, but it is still possible to find cases where installers have decided that plastic ties and plastic trunking are sufficient to be the sole means of cable support. The spacing of cable fixings is another issue where there is no scope for disregarding the manufacturer’s guidelines. What the installer has to bear in mind is that the cable system has been tested using the fixing methods and fixing distances laid down by the manufacturer".
Of course, these fixing methods and spaces affect the installation cost, and Draka acknowledges that it is understandable that they are sometimes questioned by installers. But safety and performance must come first and, with increasingly onerous legislation, they are ignored at the installer’s peril.
Then there is the issue of the cable’s stated minimum bending radius.
“The manufacturer’s typical recommendation is six-times the cable’s diameter, although too many instances have been found where this has been ignored. Again, the issue is that the installer will be responsible for proving that the cable can retain its circuit integrity at a tighter radius than the manufacturer adopted for the fire test,” observed Mark Froggatt.
Jointing of alarm cables is another area that Draka asserts demands constant attention.
“The British Standard clearly states that joints should be such that they minimise the possibility of early failure in the event of fire. It goes on to state that terminals should be constructed of materials that will withstand a similar temperature and duration to that of the cable. So there is a similar need to follow manufacturer’s guidance regarding jointing practices.”
Mark Froggatt concluded: “The agreed view within the cable industry is that joint boxes for fire systems should be metal with steel fixings, coloured red, marked ‘fire alarm’, and contain a ceramic terminal block. Such purpose-manufactured boxes are readily available on the market, so there is no excuse for making joints from boxes, glands and terminal blocks.”
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Source: Draka |
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