Unlike different cables, hearth resistant cables should work even when immediately uncovered to the fireplace to keep essential Life Safety and Fire Fighting gear working: Fire alarms, Emergency Lighting, Emergency Communication, Fire Sprinkler pumps, Fireman’s Lift sub-main, Smoke extraction fans, Smoke dampers, Stair pressurization fans, Emergency Generator circuits and so forth.
In order to categorise electrical cables as fireplace resistant they’re required to undergo testing and certification. Perhaps the primary frequent fire tests on cables were IEC 331: 1970 and later BS6387:1983 which adopted a gasoline ribbon burner check to provide a flame by which cables had been positioned.
Since the revision of BS6387 in 1994 there have been 11 enhancements, revisions or new test standards launched by British Standards for use and utility of Fire Resistant cables however none of those seem to address the core problem that fire resistant cables the place examined to widespread British and IEC flame check requirements are not required to perform to the identical fireplace efficiency time-temperature profiles as every different structure, system or component in a building. Specifically, where fire resistant structures, systems, partitions, fireplace doors, fireplace penetrations fire obstacles, floors, walls and so on. are required to be fire rated by constructing regulations, they’re examined to the Standard Time Temperature protocol of BS476 components 20 to 23 (also generally identified as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These tests are conducted in giant furnaces to replicate actual publish flashover fireplace environments. Interestingly, Fire Resistant cable check requirements like BS 6387CWZ, SS299, IEC 60331 BS8343-1 and 2, BS8491 solely require cables to be uncovered 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 prone to be exposed in the identical fireplace, and are wanted to ensure all Life Safety and Fire Fighting techniques stay operational, this reality is maybe surprising.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable methods are required to be examined to the identical hearth Time Temperature protocol as all different building parts 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 developing the standard 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 tests have been described in a collection of “Red Books” issued by the British Fire Prevention Committee after 1903 in addition to those from the German Royal Technical Research Laboratory. diaphragm seal of the ASTM commonplace was closely 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 checks 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 all know it right now and the America ASTM E119 / NFPA 251 tests probably stemmed from this time.
Image courtesy of MICC Ltd.
The curve as we see it at present (see graph above) has turn into the standard scale for measurement of fireplace take a look at severity and has proved relevant for many above ground cellulosic buildings. When components, structures, elements or methods are examined, the furnace temperatures are managed to adapt 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 conditions of assist and loading as outlined to find a way to symbolize as accurately as possible its features in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by nearly all nations around the globe for fire testing and certification of just about all constructing structures, parts, methods and parts with the fascinating exception of fireside resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand where hearth resistant cable techniques are required to be examined and approved to the Standard Time Temperature protocol, just like all other constructing structures, parts and components).
It is necessary to understand that software standards from BS, IEC, ASNZS, DIN, UL etc. where fire resistive cables are specified to be used, are only ‘minimum’ necessities. We know right now that fires are not all the same and research by Universities, Institutions and Authorities around the world have identified that Underground and a few Industrial environments can exhibit very completely different fire 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 very fast rise time and may attain temperatures well above these in above ground buildings and in far much less time. In USA right now electrical wiring techniques are required by NFPA 502 (Road Tunnels, Bridges and different Limited Access Highways) to withstand fireplace 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 more stringent check protocols for important electric cable circuits may must be considered by designers.
Standard Time Temperature curves (Europe and America) plotted in opposition to widespread BS and IEC cable checks.
Of course all underground environments whether road, rail and pedestrian tunnels, or underground public environments like shopping precincts, automobile parks etc. could exhibit totally different fire profiles to those in above ground buildings because In these environments the warmth generated by any fireplace can’t escape as easily as it would in above floor buildings thus relying more on heat and smoke extraction tools.
For Metros Road and Rail Tunnels, Hospitals, Health care amenities, Underground public environments like purchasing precincts, Very High Rise, Theaters, Public Halls, Government buildings, Airports etc. this is significantly necessary. Evacuation of those public environments is commonly sluggish even during emergencies, and it is our responsibility to ensure everyone appears to be given the very best probability of secure egress during hearth emergencies.
It is also understood right now that copper Fire Resistant cables the place installed in galvanized steel conduit can fail prematurely throughout hearth emergency due to a reaction between the copper conductors and zinc galvanizing inside the metal conduit. In 2012 United Laboratories (UL®) in America removed all certification for Fire Resistive cables where installed in galvanized metal conduit because of this:
UL® Quote: “A concern was delivered to our consideration related to the efficiency of those merchandise in the presence of zinc. We validated this finding. As a result of this, we changed our Guide Information to indicate that all conduit and conduit fittings that come in contact with fireplace resistive cables ought to have an interior coating freed from zinc”.
Time temperature profile of tunnel fires utilizing automobiles, 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 on the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would seem that some Standards authorities around the globe might have to evaluation the present test methodology presently adopted for fire resistive cable testing and maybe align the performance of Life Safety and Fire Fighting wiring techniques with that of all the other hearth resistant constructions, components and methods in order that Architects, building designers and engineers know that once they want a hearth rating that the important wiring system will be equally rated.
For many power, control, communication and knowledge circuits there is one technology available which can meet and surpass all current fireplace tests and purposes. It is a solution which is frequently utilized in demanding public buildings and has been employed reliably for over 80 years. MICC cable technology can present a total and full reply to all the issues associated with the hearth security risks of modern flexible natural polymer cables.
The metallic jacket, magnesium oxide insulation and conductors of MICC cables ensure the cable is effectively hearth proof. Bare MICC cables haven’t any natural content so merely can not 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 can’t generate any halogen or poisonous gasses at all including Carbon Monoxide. MICC cable designs can meet all the current and constructing hearth resistance performance requirements in all international locations and are seeing a major enhance in use globally.
Many engineers have beforehand thought-about MICC cable expertise to be “old school’ however with the brand new analysis in hearth performance MICC cable system are actually proven to have far superior fireplace performances than any of the newer extra modern flexible fireplace resistant cables.
For further data, go to www.temperature-house.com

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