Life Safety and Fire Fighting Systems – The weakest hyperlink

Unlike different cables, fire resistant cables have to work even when directly 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 fans, Emergency Generator circuits etc.
In order to categorise electrical cables as fireplace resistant they are required to undergo testing and certification. Perhaps the first frequent fireplace exams on cables had been IEC 331: 1970 and later BS6387:1983 which adopted a gas ribbon burner take a look at to produce a flame by which cables were positioned.
Since the revision of BS6387 in 1994 there have been 11 enhancements, revisions or new test standards launched by British Standards to be used and application of Fire Resistant cables but none of these appear to address the core issue that fireplace resistant cables the place examined to widespread British and IEC flame check standards usually are not required to perform to the identical fire efficiency time-temperature profiles as each different structure, system or component in a building. Specifically, where hearth resistant buildings, techniques, partitions, hearth doors, hearth penetrations fire limitations, floors, walls and so forth. are required to be hearth rated by constructing regulations, they’re examined to the Standard Time Temperature protocol of BS476 components 20 to 23 (also generally recognized as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These tests are conducted in large furnaces to duplicate actual post flashover hearth environments. Interestingly, Fire Resistant cable check standards like BS 6387CWZ, SS299, IEC 60331 BS8343-1 and a pair of, BS8491 only require cables to be uncovered to a flame in air and to lower final check temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are likely to be uncovered in the same fire, and are needed to ensure all Life Safety and Fire Fighting systems remain operational, this fact is perhaps shocking.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable techniques are required to be tested to the identical hearth Time Temperature protocol as all different building components and this is the Standard Time Temperature protocol to BS476pts 20-23, IS0 834-1, EN1363-1 or ASTM E119-75 in USA.
The committees growing the usual drew on the steering given from the International Fire Prevention Congress held in London in July 1903 and the measurements of furnace temperatures made in many fire exams carried out in the UK, Germany and the United States. The exams have been described in a series of “Red Books” issued by the British Fire Prevention Committee after 1903 in addition to these from the German Royal Technical Research Laboratory. The finalization of the ASTM standard 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 differences between the International ISO 834-1 take a look at as we know it today and the America ASTM E119 / NFPA 251 checks 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 usual scale for measurement of fireplace take a look at severity and has proved relevant for most above ground cellulosic buildings. When components, constructions, elements or methods are examined, the furnace temperatures are controlled to evolve to the curve with a set allowable variance and consideration for initial ambient temperatures. The standards require elements to be examined in full scale and under situations of assist and loading as defined in order to symbolize as precisely as potential its features in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by nearly all international locations around the globe for fire testing and certification of nearly all constructing structures, elements, techniques and elements with the attention-grabbing exception of fireside resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand the place hearth resistant cable methods are required to be tested and permitted to the Standard Time Temperature protocol, identical to all different building structures, components and components).
It is necessary to know that software requirements from BS, IEC, ASNZS, DIN, UL etc. where fire resistive cables are specified to be used, are only ‘minimum’ requirements. We know today that fires aren’t all the same and research by Universities, Institutions and Authorities around the globe have recognized that Underground and a few Industrial environments can exhibit very completely different hearth profiles to those in above floor cellulosic buildings. Specifically in confined เกจวัดแก๊สหุงต้ม like Road and Rail Tunnels, Underground Shopping centers, Car Parks fireplace temperatures can exhibit a very fast rise time and can attain temperatures properly above those in above floor buildings and in far much less time. In USA today electrical wiring techniques are required by NFPA 502 (Road Tunnels, Bridges and different Limited Access Highways) to resist hearth temperatures as much as 1,350 Degrees C for 60 minutes and UK British Standard BS8519:2010 clearly identifies underground public areas such as automobile parks as “Areas of Special Risk” where more stringent check protocols for essential electrical cable circuits might need to be considered by designers.
Standard Time Temperature curves (Europe and America) plotted towards frequent BS and IEC cable checks.
Of course all underground environments whether or not street, rail and pedestrian tunnels, or underground public environments like buying precincts, automobile parks and so on. might exhibit different fireplace profiles to those in above floor buildings as a end result of In these environments the heat generated by any fire can’t escape as simply as it would in above ground buildings thus relying more on warmth and smoke extraction tools.
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 etc. that is significantly important. Evacuation of those public environments is often slow even throughout emergencies, and it is our duty to ensure everyone appears to be given the perfect chance of safe egress during fire emergencies.
It can be understood right now that copper Fire Resistant cables where installed in galvanized metal conduit can fail prematurely throughout fire emergency because of a response between the copper conductors and zinc galvanizing contained in the steel conduit. In 2012 United Laboratories (UL®) in America removed all certification for Fire Resistive cables the place put in in galvanized steel conduit for this reason:
UL® Quote: “A concern was dropped at our consideration associated to the performance of these products within the presence of zinc. We validated this discovering. As a results of this, we changed our Guide Information to indicate that every one conduit and conduit fittings that are out there in contact with fire resistive cables should have an inside coating free of zinc”.
Time temperature profile of tunnel fires using 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 offered the paper at the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would appear that some Standards authorities around the world might have to evaluation the current check methodology currently adopted for hearth resistive cable testing and maybe align the efficiency of Life Safety and Fire Fighting wiring methods with that of all the other fireplace resistant buildings, parts and techniques in order that Architects, constructing designers and engineers know that when they want a fireplace score that the important wiring system might be equally rated.
For many energy, management, communication and information circuits there is one expertise available which may meet and surpass all present fire checks and purposes. It is a solution which is incessantly used in demanding public buildings and has been employed reliably for over 80 years. MICC cable know-how can present a total and complete reply to all the problems associated with the fire safety dangers of recent versatile natural polymer cables.
The steel jacket, magnesium oxide insulation and conductors of MICC cables ensure the cable is successfully hearth proof. Bare MICC cables have no natural content so simply cannot propagate flame or generate any smoke. The zero fuel-load of those 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 in any respect including Carbon Monoxide. MICC cable designs can meet all of the current and building hearth resistance efficiency requirements in all international locations and are seeing a big enhance in use globally.
Many engineers have beforehand thought of MICC cable expertise to be “old school’ but with the brand new analysis in fireplace efficiency MICC cable system are actually proven to have far superior fire performances than any of the newer extra trendy versatile fireplace resistant cables.
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