Life Safety and Fire Fighting Systems – The weakest hyperlink

Unlike other cables, fireplace resistant cables should work even when directly uncovered to the fireplace to keep important 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 and so forth.
In order to classify electrical cables as fireplace resistant they are required to endure testing and certification. Perhaps the primary frequent fire exams on cables were IEC 331: 1970 and later BS6387:1983 which adopted a gas ribbon burner take a look at to supply a flame by 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 however none of those appear to address the core concern that fire resistant cables the place examined to widespread British and IEC flame take a look at standards usually are not required to carry out to the same hearth performance time-temperature profiles as each different structure, system or part in a building. Specifically, the place hearth resistant constructions, systems, partitions, fireplace doors, fire penetrations fire obstacles, flooring, walls etc. are required to be hearth rated by building regulations, they are tested to the Standard Time Temperature protocol of BS476 components 20 to 23 (also known as ISO834-1, ASNZS1530pt4, EN1363-1 and in America and Canada ASTM E119-75).
These checks are conducted in massive furnaces to duplicate actual publish flashover hearth environments. Interestingly, Fire Resistant cable test standards 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 ultimate check temperatures (than required by BS476 pts 20 to 23). Given Fire Resistant cables are more probably to be exposed in the identical fireplace, and are wanted to make sure all Life Safety and Fire Fighting methods stay operational, this reality is maybe shocking.
Contrastingly in Germany, Belgium, Australia, New Zealand, USA and Canada Fire Resistant cable methods are required to be tested to the identical fire 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 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 fireplace exams carried out in the UK, Germany and the United States. The tests were described in a series 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 commonplace was heavily influenced by Professor I.H. Painless , 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 take a look at as we all know it at present and the America ASTM E119 / NFPA 251 tests likely 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 take a look at severity and has proved related for most above floor cellulosic buildings. When parts, buildings, parts or systems are examined, the furnace temperatures are managed to conform 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 beneath conditions of support and loading as defined in order to represent as accurately as possible its features in service.
This Standard Time Temperature testing protocol (see graph right) is adopted by almost all nations around the world for fireplace testing and certification of nearly all building buildings, elements, systems and components with the fascinating exception of fire resistant cables (exception in USA, Canada, Australia, Germany, Belgium and New Zealand where fire resistant cable systems are required to be tested and permitted to the Standard Time Temperature protocol, identical to all different building constructions, parts and components).
It is important to grasp that software requirements from BS, IEC, ASNZS, DIN, UL etc. the place fireplace resistive cables are specified for use, are solely ‘minimum’ necessities. We know at present that fires usually are not all the same and research by Universities, Institutions and Authorities around the globe have recognized that Underground and some Industrial environments can exhibit very totally different fireplace profiles to those in above floor cellulosic buildings. Specifically in confined underground public areas like Road and Rail Tunnels, Underground Shopping centers, Car Parks fire temperatures can exhibit a really quick rise time and can reach temperatures properly above these in above ground buildings and in far less time. In USA right now electrical wiring systems are required by NFPA 502 (Road Tunnels, Bridges and different Limited Access Highways) to face up to 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” where extra 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 frequent BS and IEC cable tests.
Of course all underground environments whether street, rail and pedestrian tunnels, or underground public environments like shopping precincts, car parks and so on. might exhibit completely different hearth profiles to these in above ground buildings as a result of In these environments the heat generated by any fireplace cannot escape as easily as it would in above floor buildings thus relying more on heat and smoke extraction equipment.
For Metros Road and Rail Tunnels, Hospitals, Health care facilities, Underground public environments like purchasing precincts, Very High Rise, Theaters, Public Halls, Government buildings, Airports and so on. this is significantly important. Evacuation of those public environments is usually slow even during emergencies, and it is our duty to ensure everyone appears to be given the very best likelihood of protected egress during fire emergencies.
It is also understood today that copper Fire Resistant cables where put in in galvanized metal conduit can fail prematurely during fireplace emergency because of a response between the copper conductors and zinc galvanizing contained in the metal conduit. In 2012 United Laboratories (UL®) in America removed all certification for Fire Resistive cables the place put in in galvanized metal conduit because of this:
UL® Quote: “A concern was brought to our attention associated to the efficiency of those products in 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 contact with fire resistive cables should have an interior coating free of zinc”.
Time temperature profile of tunnel fires using automobiles, HGV trailers with different cargo and rail carriages. Graph extract: Haukur Ingason and Anders Lonnermark of the Swedish National Testing and Research Institute who presented the paper on the First International Symposium in Prague 2004: Safe and Reliable Tunnels.
It would appear that some Standards authorities all over the world could have to evaluate the current check methodology currently adopted for fireplace resistive cable testing and perhaps align the performance of Life Safety and Fire Fighting wiring systems with that of all the opposite fire resistant structures, elements and systems in order that Architects, building designers and engineers know that after they need a fireplace ranking that the important wiring system shall be equally rated.
For many power, control, communication and data circuits there is one expertise obtainable which might meet and surpass all present hearth tests and applications. It is a solution which is regularly utilized in demanding public buildings and has been employed reliably for over 80 years. MICC cable expertise can present a total and full reply to all the issues associated with the fireplace safety risks of modern flexible organic 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 material so merely 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 can not generate any halogen or toxic gasses at all together with Carbon Monoxide. MICC cable designs can meet all of the current and constructing fire resistance efficiency standards in all international locations and are seeing a major enhance in use globally.
Many engineers have previously thought-about MICC cable know-how to be “old school’ however with the new research in fire performance MICC cable system at the moment are proven to have far superior fire performances than any of the newer more trendy flexible fire resistant cables.
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