Life Safety and Fire Fighting Systems – The weakest link

Unlike different cables, fire resistant cables should work even when immediately exposed to the hearth to keep essential Life Safety and Fire Fighting equipment working: Fire alarms, Emergency Lighting, Emergency Communication, Fire Sprinkler pumps, Fireman’s Lift sub-main, Smoke extraction followers, Smoke dampers, Stair pressurization followers, Emergency Generator circuits and so forth.
In order to categorise electric cables as fireplace resistant they are required to undergo testing and certification. Perhaps the first frequent fireplace checks on cables had been IEC 331: 1970 and later BS6387:1983 which adopted a gasoline ribbon burner test to supply a flame during which cables have been positioned.
Since the revision of BS6387 in 1994 there have been eleven enhancements, revisions or new take a look at standards launched by British Standards to be used and software of Fire Resistant cables but none of those seem to handle the core issue that fireside resistant cables where tested to widespread British and IEC flame check requirements are not required to perform to the identical fire efficiency time-temperature profiles as each different construction, system or part in a constructing. Specifically, the place hearth resistant structures, systems, partitions, hearth doorways, fireplace penetrations hearth barriers, flooring, walls and so forth. are required to be fire rated by building rules, they are examined to the Standard Time Temperature protocol of BS476 parts 20 to 23 (also generally recognized as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These checks are performed in giant furnaces to replicate real submit flashover hearth environments. Interestingly, Fire Resistant cable take a look at requirements like BS 6387CWZ, SS299, IEC 60331 BS8343-1 and a pair of, BS8491 only require cables to be exposed to a flame in air and to lower final take a look at temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are likely to be uncovered in the identical fireplace, and are wanted to make sure all Life Safety and Fire Fighting systems stay operational, this reality is perhaps stunning.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable methods are required to be examined to the identical fireplace Time Temperature protocol as all other building elements and that is the Standard Time Temperature protocol to BS476pts 20-23, IS0 834-1, EN1363-1 or ASTM E119-75 in USA.
The committees creating the usual drew on the guidance given from the International Fire Prevention Congress held in London in July 1903 and the measurements of furnace temperatures made in lots of fireplace exams carried out in the UK, Germany and the United States. The exams had been described in a sequence of “Red Books” issued by the British Fire Prevention Committee after 1903 as properly as those from the German Royal Technical Research Laboratory. The finalization of the ASTM commonplace was heavily influenced by Professor I.H. Woolson, a Consulting Engineer of the USA National Board of Fire Underwriters and Chairman of the NFPA committee in Fire Resistive Construction who had carried out many tests at Columbia University and Underwriters Laboratories in Chicago. The small time temperature variations between the International ISO 834-1 check as we all know it today and the America ASTM E119 / NFPA 251 exams probably stemmed from this time.
Image courtesy of MICC Ltd.
The curve as we see it at present (see graph above) has turn out to be the standard scale for measurement of fireplace test severity and has proved related for most above floor cellulosic buildings. When elements, buildings, parts or systems are tested, the furnace temperatures are controlled to evolve to the curve with a set allowable variance and consideration for initial ambient temperatures. The requirements require parts to be examined in full scale and underneath situations of help and loading as outlined so as to characterize as precisely as attainable its capabilities in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by virtually all nations around the globe for hearth testing and certification of just about all constructing constructions, components, methods and components with the interesting exception of fireside resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand where fire resistant cable systems are required to be examined and accredited to the Standard Time Temperature protocol, identical to all different building structures, parts and components).
It is important to know that application standards from BS, IEC, ASNZS, DIN, UL and so on. the place fire resistive cables are specified to be used, are solely ‘minimum’ requirements. We know at present that fires aren’t all the identical and research by Universities, Institutions and Authorities all over the world have recognized that Underground and a few Industrial environments can exhibit very completely different fireplace profiles to these in above floor cellulosic buildings. Specifically in confined underground public areas like Road and Rail Tunnels, Underground Shopping centers, Car Parks hearth temperatures can exhibit a really quick rise time and might reach temperatures nicely above these in above floor buildings and in far less time. In USA right now electrical wiring systems are required by NFPA 502 (Road Tunnels, Bridges and other Limited Access Highways) to withstand hearth temperatures up to 1,350 Degrees C for 60 minutes and UK British Standard BS8519:2010 clearly identifies underground public areas corresponding to automobile parks as “Areas of Special Risk” the place extra stringent take a look at protocols for important electrical cable circuits might must be thought-about by designers.
Standard Time Temperature curves (Europe and America) plotted in opposition to frequent BS and IEC cable checks.
Of course all underground environments whether street, rail and pedestrian tunnels, or underground public environments like shopping precincts, car parks and so forth. might exhibit completely different fireplace profiles to those in above floor buildings as a end result of In these environments the heat generated by any hearth cannot escape as easily as it might in above floor buildings thus relying more on heat and smoke extraction equipment.
For Metros Road and Rail Tunnels, Hospitals, Health care amenities, Underground public environments like shopping precincts, Very High Rise, Theaters, Public Halls, Government buildings, Airports and so forth. this is notably essential. Evacuation of those public environments is often slow even throughout emergencies, and it’s our duty to ensure everyone appears to be given the easiest probability of secure egress during fire emergencies.
ราคาเกจวัดแรงดันลม can also be understood at present that copper Fire Resistant cables the place put in in galvanized steel conduit can fail prematurely during fire emergency because of a reaction between the copper conductors and zinc galvanizing contained in the metallic conduit. In 2012 United Laboratories (UL®) in America eliminated all certification for Fire Resistive cables the place installed in galvanized steel conduit for that reason:
UL® Quote: “A concern was delivered to our consideration associated to the efficiency of those merchandise in the presence of zinc. We validated this discovering. As a results of this, we modified our Guide Information to point that all conduit and conduit fittings that are available contact with hearth resistive cables ought to have an interior coating free of zinc”.
Time temperature profile of tunnel fires utilizing vehicles, HGV trailers with completely different cargo and rail carriages. Graph extract: Haukur Ingason and Anders Lonnermark of the Swedish National Testing and Research Institute who introduced the paper on the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would seem that some Standards authorities around the world could must evaluate the present test methodology at present adopted for hearth resistive cable testing and maybe align the efficiency of Life Safety and Fire Fighting wiring techniques with that of all the other fireplace resistant structures, components and methods in order that Architects, constructing designers and engineers know that once they need a fire rating that the essential wiring system will be equally rated.
For many power, control, communication and data circuits there’s one expertise obtainable which can meet and surpass all current hearth checks and applications. It is an answer which is frequently used in demanding public buildings and has been employed reliably for over 80 years. MICC cable expertise can present a complete and complete answer to all the issues related to the fireplace security dangers of recent flexible natural polymer cables.
The metallic jacket, magnesium oxide insulation and conductors of MICC cables ensure the cable is successfully fire proof. เกจวัดแรง can’t propagate flame or generate any smoke. The zero fuel-load of these MICC cables ensures no warmth is added to the fireplace and no oxygen is consumed. Being inorganic these MICC cables cannot generate any halogen or toxic gasses at all including Carbon Monoxide. MICC cable designs can meet the entire current and building fire resistance efficiency standards in all international locations and are seeing a significant improve in use globally.
Many engineers have beforehand thought-about MICC cable expertise to be “old school’ however with the model new research in fireplace performance MICC cable system at the moment are confirmed to have far superior fireplace performances than any of the newer extra fashionable flexible hearth resistant cables.
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