Life Safety and Fire Fighting Systems – The weakest hyperlink

Unlike different cables, fire resistant cables have to work even when instantly exposed to the hearth to maintain important 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 etc.
In order to classify electric cables as hearth resistant they’re required to bear testing and certification. Perhaps the primary common fire tests on cables have been IEC 331: 1970 and later BS6387:1983 which adopted a fuel ribbon burner take a look at to produce a flame during which cables were placed.
Since the revision of BS6387 in 1994 there have been 11 enhancements, revisions or new test standards introduced by British Standards for use and utility of Fire Resistant cables but none of these appear to address the core concern that fireplace resistant cables the place examined to common British and IEC flame check standards usually are not required to perform to the same hearth performance time-temperature profiles as each different construction, system or element in a building. Specifically, where fire resistant constructions, systems, partitions, hearth doors, fire penetrations fireplace obstacles, floors, partitions and so forth. are required to be fire rated by constructing laws, they’re examined to the Standard Time Temperature protocol of BS476 elements 20 to 23 (also generally identified as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These tests are performed in giant furnaces to duplicate actual post flashover fire environments. Interestingly, Fire Resistant cable check requirements 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 ultimate take a look at temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are likely to be exposed in the same fireplace, and are wanted to ensure all Life Safety and Fire Fighting systems stay operational, this truth is probably shocking.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable techniques are required to be examined to the identical hearth Time Temperature protocol as all other constructing 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 standard 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 many fireplace checks 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 nicely as these from the German Royal Technical Research Laboratory. The finalization 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 today and the America ASTM E119 / NFPA 251 tests likely stemmed from this time.
Image courtesy of MICC Ltd.
The curve as we see it today (see graph above) has become the standard scale for measurement of fire check severity and has proved relevant for many above floor cellulosic buildings. When elements, buildings, elements or systems are tested, the furnace temperatures are managed to conform to the curve with a set allowable variance and consideration for initial ambient temperatures. The requirements require elements to be tested in full scale and underneath situations of help and loading as outlined in order to symbolize as precisely as possible its capabilities in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by nearly all nations all over the world for fireplace testing and certification of nearly all constructing structures, elements, methods and elements with the fascinating exception of fireplace resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand the place fire resistant cable techniques are required to be tested and approved to the Standard Time Temperature protocol, just like all different constructing structures, elements and components).
It is necessary to understand that software requirements from BS, IEC, ASNZS, DIN, UL and so on. where hearth resistive cables are specified to be used, are only ‘minimum’ necessities. We know right now that fires aren’t all the same and analysis 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 those in above floor cellulosic buildings. Specifically in confined underground public areas like Road and Rail Tunnels, Underground Shopping facilities, Car Parks hearth temperatures can exhibit a really fast rise time and may attain temperatures properly above these in above ground buildings and in far less time. In USA right now electrical wiring methods are required by NFPA 502 (Road Tunnels, Bridges and different Limited Access Highways) to face up to fireplace 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” the place extra stringent take a look at protocols for important electric cable circuits might have to be thought-about by designers.
Standard Time Temperature curves (Europe and America) plotted towards common BS and IEC cable checks.
Of เกจอาร์กอน whether or not road, rail and pedestrian tunnels, or underground public environments like buying precincts, automotive parks and so on. might exhibit totally different fire profiles to those in above ground buildings as a outcome of In these environments the heat generated by any fire cannot escape as simply as it might in above floor buildings thus relying extra on warmth and smoke extraction equipment.
For Metros Road and Rail Tunnels, Hospitals, Health care amenities, Underground public environments like buying precincts, Very High Rise, Theaters, Public Halls, Government buildings, Airports etc. that is particularly necessary. Evacuation of these public environments is usually gradual even throughout emergencies, and it’s our duty to make sure everyone appears to be given the easiest likelihood of safe egress throughout fireplace emergencies.
It can be understood right now that copper Fire Resistant cables the place put in in galvanized metal conduit can fail prematurely during fireplace emergency due to a reaction between the copper conductors and zinc galvanizing inside the steel conduit. In 2012 United Laboratories (UL®) in America eliminated all certification for Fire Resistive cables the place installed in galvanized steel conduit because of this:
UL® Quote: “A concern was dropped at our attention associated to the performance of those merchandise within the presence of zinc. We validated this discovering. As a result of this, we modified our Guide Information to point that all conduit and conduit fittings that are available in contact with fireplace resistive cables ought to have an interior coating free of zinc”.
Time temperature profile of tunnel fires using vehicles, HGV trailers with totally 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 appear that some Standards authorities around the world might need to evaluation the present take a look at methodology at present adopted for fire 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 so that Architects, constructing designers and engineers know that once they want a hearth score that the essential wiring system might be equally rated.
For many energy, control, communication and data circuits there is one technology obtainable which can meet and surpass all present fireplace exams and applications. It is an answer which is incessantly utilized in demanding public buildings and has been employed reliably for over 80 years. MICC cable know-how can provide a complete and complete reply to all the problems related to the fireplace security risks of modern versatile organic polymer cables.
The metal jacket, magnesium oxide insulation and conductors of MICC cables make positive the cable is effectively fire proof. Bare MICC cables don’t have any natural content so merely can not propagate flame or generate any smoke. The zero fuel-load of these MICC cables ensures no warmth is added to the hearth and no oxygen is consumed. Being inorganic these MICC cables cannot generate any halogen or toxic gasses at all together with Carbon Monoxide. MICC cable designs can meet all the present and building fire resistance performance standards in all countries and are seeing a significant enhance in use globally.
Many engineers have previously thought of MICC cable expertise to be “old school’ but with the model new research in fire performance MICC cable system are now proven to have far superior fire performances than any of the newer extra modern versatile fire resistant cables.
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