클잼 로고

• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

It could be between people or between computers, but without proper communication, the exchange of information cannot take place. When the body is exposed to a high voltage surge, it can take years to recover. It is a solution that is frequently used in demanding public buildings and has been employed reliably for over 80 years. MICC cable technology provides a comprehensive solution to all the problems associated with the fire safety dangers of modern flexible organic polymer cables. The copper jacket, magnesium oxide insulation and copper conductors of MICC cables ensure the cable is effectively fireproof. These situations can cause high temperatures in the cable conductors or electrical arcing which may heat the cable insulation and any surrounding combustible materials to start a fire. This means that burning polyethylene will not only generate almost 3 times more heat but also consume almost 3 times more oxygen and produce significantly larger amounts of Carbon Monoxide especially with partial or incomplete burning. Highly flame retardant cables with a high oxygen index may help here because they may limit the fire spread. Simply specifying low smoke cables to common British or IEC standards then thinking this will provide a low smoke environment during a real fire may unfortunately, in practice, be of little help for the people actually involved.

In America, many building standards do not require halogen free cables. The higher the heat of combustion (MJ/Kg) the more oxygen is needed, so by choosing insulations (even if Halogen Free) with high fuel elements is adding significantly to at least four of the primary dangers of fire: Temperature rise, Oxygen depletion, Toxic gas emission, and Flame spread. Burning Polyethylene (which can be seen from the table above has the highest MJ fuel load per Kg of all insulations) will generate almost 3 times more heat than an equivalent PVC cable. The fuel elements shown in the table above (pic 1) indicate the amount of heat that will be generated by burning 1kg of the common cable insulations tabled. The zero fuel load of these MICC cables ensures no heat is added to the fire and no oxygen is consumed. MICC cables have no organic content so simply cannot propagate flame or generate any smoke.

Enclosing cables in steel conduit will reduce flame propagation at the point of fire but hydrocarbon based combustion gasses and smoke from the decomposing polymers will propagate along the inside of conduits to switchboards, distribution boards and junction boxes in other parts of the building where any spark such as the opening or closing of circuit breakers, or contactors is likely to ignite the combustible gasses leading to ignition or even explosion and spreading of the fire and smoke to other locations. As we know presence of halogenated materials will release toxic halides like Hydrogen Chloride together with many other toxic and flammable gasses in the smoke. These halogenated polymers (example: PVC) also have a negative side-effect because in the fire they will release the halogens as halides which are extremely toxic and when combined with moisture in the eyes, nose, mouth, and lungs are very irritant. This has significance because while cables with a flame retardant outer jacket may pass flame retardance tests with an external flame, the same cables when subjected to high overload or prolonged short circuits have proved in university tests to be highly flammable and can even start a fire.

Where cables are required to be flame retardant to Australian Standard test methods AS/NZS60332-3 it is concerning these tests are not conducted on cable samples preconditioned to the operating temperature, rather commencing at room temperature. For this reason common British, IEC and Austrlian (AS/NZS61034) smoke tests conducted by burning cable samples in large 3 meter³ chambers with plenty of air may provide misleading smoke figures because complete burning in flame can release less smoke than partial incomplete burning or smoldering which is likely in practice (in America NFPA 130 calls for smoke tests in both flaming and non-flaming modes). These include air quality, water, soil and noise, hazardous waste management, and efficient solid waste as well as various aspects of occupational health and safety of others. The popularity of "Halogen Free" properties while ignoring the other toxic elements of a fire is a clear admission we do not understand the subject well nor can we easily define the dangers of combined toxic elements or human physiological response to them. It is concerning that the UK, Europe, Australia and other countries often adopt the concept of halogen free cables without fully addressing the subject of toxicity.

Here's more regarding what is electric cable stop by our web-page.