Unlike other cables, fire resistant cables have to work even when instantly 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 followers, Smoke dampers, Stair pressurization followers, Emergency Generator circuits and so on.
In order to classify electric cables as fire resistant they are required to bear testing and certification. Perhaps the first common fire tests on cables were IEC 331: 1970 and later BS6387:1983 which adopted a fuel ribbon burner take a look at to produce a flame during which cables had been placed.
Since the revision of BS6387 in 1994 there have been 11 enhancements, revisions or new test standards launched by British Standards for use and software of Fire Resistant cables however none of those appear to deal with the core issue that fireplace resistant cables the place examined to common British and IEC flame take a look at standards are not required to carry out to the identical fireplace performance time-temperature profiles as every other structure, system or component in a constructing. Specifically, the place fireplace resistant constructions, techniques, partitions, hearth doorways, fireplace penetrations fireplace barriers, flooring, walls and so on. are required to be hearth rated by constructing regulations, they are examined to the Standard Time Temperature protocol of BS476 parts 20 to 23 (also known as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These checks are performed in giant furnaces to replicate actual publish flashover fireplace environments. Interestingly, Fire Resistant cable test requirements like BS 6387CWZ, SS299, IEC 60331 BS8343-1 and 2, BS8491 only require cables to be uncovered to a flame in air and to lower last test temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are more probably to be uncovered in the identical fireplace, and are needed to make sure all Life Safety and Fire Fighting techniques stay operational, this fact is perhaps stunning.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable techniques are required to be examined to the identical fireplace Time Temperature protocol as all different 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 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 had 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. 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 checks at Columbia University and Underwriters Laboratories in Chicago. The small time temperature variations between the International ISO 834-1 test as we know it right now and the America ASTM E119 / NFPA 251 exams doubtless stemmed from this time.
Image courtesy of MICC Ltd.
The curve as we see it right now (see graph above) has turn into the standard scale for measurement of fireplace take a look at severity and has proved related for most above ground cellulosic buildings. When elements, constructions, components or techniques are tested, the furnace temperatures are controlled to evolve to the curve with a set allowable variance and consideration for preliminary ambient temperatures. The standards require elements to be tested in full scale and underneath circumstances of support and loading as defined to be able to characterize as precisely as possible its capabilities in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by almost all international locations around the globe for hearth testing and certification of nearly all constructing buildings, elements, systems and elements with the attention-grabbing exception of fireplace resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand the place fireplace resistant cable methods are required to be examined and accredited to the Standard Time Temperature protocol, similar to all other constructing structures, parts and components).
digital pressure gauge is important to understand that application standards from BS, IEC, ASNZS, DIN, UL and so forth. where fireplace resistive cables are specified to be used, are only ‘minimum’ requirements. We know at present that fires are not all the same and analysis by Universities, Institutions and Authorities around the world have recognized that Underground and some Industrial environments can exhibit very completely different hearth profiles to these in above floor cellulosic buildings. Specifically in confined underground public areas like Road and Rail Tunnels, Underground Shopping facilities, Car Parks fireplace temperatures can exhibit a very quick rise time and may attain temperatures properly above these in above floor buildings and in far much less time. In USA today electrical wiring methods 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 similar to automobile parks as “Areas of Special Risk” the place extra stringent check protocols for important electric cable circuits could need to be thought of by designers.
Standard Time Temperature curves (Europe and America) plotted against frequent BS and IEC cable exams.
Of course all underground environments whether highway, rail and pedestrian tunnels, or underground public environments like buying precincts, automotive parks and so forth. may exhibit completely different fireplace profiles to these in above ground buildings as a end result of In these environments the heat generated by any fireplace cannot escape as easily as it might in above ground buildings thus relying extra on warmth and smoke extraction gear.
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 notably important. Evacuation of these public environments is commonly gradual even throughout emergencies, and it’s our responsibility to make sure everyone seems to be given the perfect chance of safe egress throughout hearth emergencies.
It can be understood at present that copper Fire Resistant cables where put in in galvanized metal conduit can fail prematurely throughout fire emergency due to a response between the copper conductors and zinc galvanizing contained in the steel conduit. In 2012 United Laboratories (UL®) in America eliminated all certification for Fire Resistive cables the place put in in galvanized steel conduit for that reason:
UL® Quote: “A concern was dropped at our attention related to the performance of those merchandise within the presence of zinc. We validated this discovering. As a results of this, we changed our Guide Information to indicate that all conduit and conduit fittings that come in contact with fire resistive cables should 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 presented the paper at the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would seem that some Standards authorities around the world may need to evaluation the current check methodology presently adopted for fireplace resistive cable testing and maybe align the efficiency of Life Safety and Fire Fighting wiring methods with that of all the opposite fire resistant constructions, parts and systems so that Architects, building designers and engineers know that after they need a fire score that the essential wiring system shall be equally rated.
For many power, control, communication and information circuits there is one know-how obtainable which might meet and surpass all current fire checks 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 full reply to all the problems related to the fireplace safety risks of contemporary versatile natural polymer cables.
The metallic jacket, magnesium oxide insulation and conductors of MICC cables make positive the cable is effectively hearth 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 fire 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 of the present and building fireplace resistance efficiency standards in all international locations and are seeing a significant enhance in use globally.
Many engineers have previously thought of MICC cable technology to be “old school’ however with the new research in hearth performance MICC cable system are now proven to have far superior hearth performances than any of the newer more modern flexible hearth resistant cables.
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