MR refers to galvanized wire groove, also called metal wire groove. CT refers to the trough bridge, the trough bridge is also called the trough cable bridge, it is a. The National Electric Code (NEC) defines tray cable as: “a factory assembly of two or more insulated conductors, with or without associated bare or covered grounding conductors under a nonmetallic sheath, for installation in cable trays, in raceways, or where supported by a messenger wire. ” Simply. B manufactures its cable tray in a range of materials with a variety of finishes. The selection of material and finish is a function of the environment in wh tant in a wide range of environments, and easily formable (Appendices II and III). Through NEMA and the Cable Tray Institute numerous articles, standards, and other general guidance can be found regarding the proper use and installation of cable tray systems.
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