Underwriters Laboratories Inc. is an independent company that conducts safety and performance testing on a wide variety of products, including wire and cable. The company's website notes that in 2010, there were 66,932 manufacturers worldwide producing UL-certified products. You can tell if a network cable has been rated by UL by looking for the "UL" designation on the side of the cable, with additional details on the tag the UL wire cable came with.
Labeling
Underwriters Laboratories requires that participating manufacturers label the cable directly with its rating. A local area network (LAN) and fiber optic cable that has been rated by UL must have "UL" printed on the cable, either in parenthesis or in a circle. The cable must also have the manufacturer's name, trademark or UL file number printed on it. The UL file number begins with an "E" in the format "E-xxxx." Local area network cables also display the xlpe wire cable type, the size and number of conductors in the cable, as well as the cable's temperature rating. Both types of cable must also be tagged with a UL verification label, which includes the above information as well as the cable footage and a UL issue number.
LAN Cable Safety Ratings
Local area network cables are marked with one of six designations to identify their safety rating by UL. "CM" indicates a cable is intended for general use within buildings; "CMG" indicates the same as "CM," with the additional indication that the damage height of the cable does not exceed 59 inches; "CMP" indicates plenum-rated cable for use in ducts or above plenum ceilings; "CMR" indicates the cable is rated for use within buildings in vertical shafts; "CMUC" indicates the cable is rated for use below carpet; "CMX" indicates the cable is rated for use within buildings enclosed in noncombustible tubing or nonconcealed spaces if that space does not exceed 10 feet; and "CMX" cable that is also marked "Outdoor" can be used outdoors.
Showing posts with label cable. Show all posts
Showing posts with label cable. Show all posts
Tuesday, April 17, 2012
Tuesday, March 6, 2012
PVC Insulated Electrical Wiring Hazards
PVC, or polyvinyl chloride, began to be used with electrical wiring in the 1930s to replace rubber insulation. While this type of insulation is considered to be safe for electrical wiring insulation, if the wire is used outside of the recommended specifications then dangers, such as electrical fire, can occur. To avoid PVC hazards, make sure you use PVC insulated wire in the right circumstances.
Temperature
The maximum working temperature of PVC is 70 degrees Celsius. At temperatures higher than 70 degrees Celsius the PVC starts to soften and become leeched away. This can result in open live PVC insulation wire, which can cause short circuits and electrical fires. Be aware that if the wire has a low level of electricity running through it but positioned next to a heating pipe, this can cause temperatures to rise too high and damage will ensue. When PVC is exposed to low temperatures, close to freezing, the PVC becomes brittle and the insulation can crack and expose the live wire. Ensure that all PVC insulated wires are stored and used at optimal temperatures.
Fire
For many years it was thought that PVC insulated wire was fireproof as the PVC would ignite briefly but then self extinguish. To some extent this is still true. However if the PVC insulated wire is found at a packing density of one kg PVC/m and a piece of wire should ignite or catch fire then there is enough PVC to remain lit. One such example where such high packing density of PVC insulated wire is found is in a cable tunnel.
Hydrogen Chloride Gas
Should PVC insulated wire catch fire, the burning of PVC releases hydrogen chloride gas. If large enough amounts of PVC catch fire and there is not proper ventilation, or any individuals trying to access the fire area do not wear proper breathing equipment, then hydrogen chloride gas can cause death.
Smoke
Before PVC actually ignites it produces a very dense, black smoke that will quickly block any light, resulting in a pitch-black environment. The loss of visibility makes, location, rescue and escape very difficult, and in fact the smoke is considered to be more dangerous than an electrical fire.
Temperature
The maximum working temperature of PVC is 70 degrees Celsius. At temperatures higher than 70 degrees Celsius the PVC starts to soften and become leeched away. This can result in open live PVC insulation wire, which can cause short circuits and electrical fires. Be aware that if the wire has a low level of electricity running through it but positioned next to a heating pipe, this can cause temperatures to rise too high and damage will ensue. When PVC is exposed to low temperatures, close to freezing, the PVC becomes brittle and the insulation can crack and expose the live wire. Ensure that all PVC insulated wires are stored and used at optimal temperatures.
Fire
For many years it was thought that PVC insulated wire was fireproof as the PVC would ignite briefly but then self extinguish. To some extent this is still true. However if the PVC insulated wire is found at a packing density of one kg PVC/m and a piece of wire should ignite or catch fire then there is enough PVC to remain lit. One such example where such high packing density of PVC insulated wire is found is in a cable tunnel.
Hydrogen Chloride Gas
Should PVC insulated wire catch fire, the burning of PVC releases hydrogen chloride gas. If large enough amounts of PVC catch fire and there is not proper ventilation, or any individuals trying to access the fire area do not wear proper breathing equipment, then hydrogen chloride gas can cause death.
Smoke
Before PVC actually ignites it produces a very dense, black smoke that will quickly block any light, resulting in a pitch-black environment. The loss of visibility makes, location, rescue and escape very difficult, and in fact the smoke is considered to be more dangerous than an electrical fire.
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