User:Skenady58

Cable trays are used typically as raceways for cables and wires. A [cable tray] system supports and protects both power and signal cables and allows cabling networks to be upgraded, reconfigured, or relocated. Cable tray systems can have several designs, including ladder, solid bottom, channel, trough, wire mesh, and single rail. A metallic cable tray is made of steel or aluminum. A non-metallic cable tray can be made of polyvinyl chloride (PVC) or fiberglass. PVC cable trays are an aluminum cable tray or a steel cable tray with PVC coating. A wire mesh cable tray provides a field-adaptable system for low voltage, telecommunication and fiber optic cables. Use of a cable tray roller can reduce pulling stress on cables, shear load on cable trays, and overall installation time. The amount of cable tray wire that can be installed in a cable tray varies with the type of cable (e.g., twisted pair, coaxial, and fiber optic). Cable tray manufacturers are located across the United States and around the world. Considerations for cable trays include environmental conditions (ice, wind, snow,), corrosion requirements, and weight of the installed cable. Other considerations for cable trays include the type and number of cables to support, the bending radius of the cable, able entry / exit freedom, installation design, expandability, heat generated, and length of support spans. The National Electrical Manufacturers Association (NEMA) publishes several documents regarding cable trays. NEMA VE1 covers general cable tray definitions, manufacturing standards, performance standards, test standards, and application information. NEMA VE2 is a cable tray installation guideline. NEMA FG1 covers fiberglass cable tray systems. Articles 250, 318, 392, and 800 of the National Electrical Code (NEC) also cover various aspects of cable trays. An electrical cable tray can be UL-classified if it is used as an equipment grounding conductor. Underwriters Laboratory (UL) and American National Standards Institute (ANSI) maintain ANSI/UL 568 for nonmetallic cable tray systems. A fiberglass cable tray can meet ASTM D-635 (flame rating and self-extinguishing requirements) and ASTM E-84 (smoke density rating) In its most popular form, a cable tie consists of a sturdy Nylon tape with an integrated gear rack, and on one end a ratchet within a small open case. Once the pointed tip of the cable ties has been pulled through the case and past the ratchet, it is prevented from being pulled back; the resulting loop may only be pulled tighter. In two of its most common uses, this allows several cables to be bound together into a cable tree, or to be used as makeshift handcuffs as in Panamá, the U.K. and the U.S.A. Specially constructed physical restraints called PlastiCuffs, based on the cable ties design, are used by police and military to restrain prisoners, especially in the more urban parts of the U.S.A. and Panamá. Cable ties are also commonly used to prevent hubcaps (also known as wheel trims) from falling off a moving vehicle, and some are sold specifically for this purpose.

A cable tie tensioning device or tool may be used to apply a cable ties with a specific degree of tension. The tool may cut off the extra tail flush with the head in order to avoid a sharp edge which might otherwise cause injury.

In order to increase resistance to ultraviolet light in outdoor applications, a specific grade of Nylon containing a minimum of 2% carbon black is used to protect the polymer chains and extend the cable tie's service life.[1] Blue cable ties are supplied to the food industry and contain a metal additive so they can be detected by industrial metal detectors. Cable ties made of ETFE (Tefzel) are used in a radiation-rich environment. Red cable ties made of ECTFE (Halar) are used for plenum cabling.

Stainless Steel cable ties are also available for flameproof applications - coated stainless ties are available to prevent galvanic attack from dissimilar metals (e.g. zinc coated cable tie).

History

Cable ties were first invented by Thomas & Betts, an electrical company, in 1958 under the brand name Ty-Rap initially designed for airplane wire harnesses. The original design used a metal ratchet instead of nylon, they later changed to the nylon/plastic design.

Reuse

[Cable ties] are generally viewed as single-use devices. However, if a closed loop needs to be opened again, then, rather than destroying the cable tie by cutting, it may be possible to release the ratchet from the rack to reuse the cable tie. While some cable ties are designed for reuse with a tab that releases the ratchet, in most cases a sewing needle or similar object (for example a small screwdriver) will need to be interposed between the ratchet and the rack. Ties reused in this way will be weaker than new ones.

To open without cutting it, the ratchet box can be crushed vertically using pliers