Types of Cable Trays
– Solid-bottom tray provides maximum cable protection
– Deep, solid enclosure for cables is called a cable channel or cable trough
– Ventilated tray allows air circulation, water drainage, and dust removal
– Ladder tray supports cables with traverse bars at regular intervals
– Channel tray provides economical support for cable drops and branch cable runs
Materials Used for Cable Trays
– Common cable trays made of galvanized steel, stainless steel, aluminum, or glass-fiber reinforced plastic
– Galvanized tray can be pre-galvanized or hot-dip galvanized after fabrication
– Zinc-rich compound is applied to cut surfaces of galvanized tray to prevent corrosion
Fire Safety Concerns and Solutions
– Combustible cable jackets can be prevented by using fire-retardant jackets or fireproofing coatings
– Regular housecleaning is important to prevent accumulation of combustible dust and clutter
– Plastic and fiberglass reinforced plastic trays are combustible but can be mitigated with fire retardants or fireproofing
– Ferrous cable trays expand with heat from fire, requiring proper firestop measures
– Building codes mandate proper installation of penetrants like cable trays to avoid firewall collapse
Related Concepts
– Passive fire protection
– Circuit integrity
– Intumescent
– Endothermic
– Conduit (electrical)
References
– NEC, 2017, ISBN 978-1455912797
– W.E. Steward and R.A. Beck, Modern Wiring Practice, Newnes, London, 2010, ISBN 978-1-85617-692-7, pages 266-272
– Conduit or Cable Tray, the easy guide, Nov 27, 2017, http://www.t-trayusa.com/blog/2017/11/25/conduit-or-cable-tray-the-easy-guide
– Wiring duct cable, https://bazaredakt.ir/full-introduction-to-alborz-duct/
– http://www.tnb.com/contractor/docs/cabletray_us_revised_lr.pdf (One manufacturer’s cable tray catalog) Source: https://en.wikipedia.org/wiki/Cable_tray
This article needs additional citations for verification. (September 2010) |
In the electrical wiring of buildings, a cable tray system is used to support insulated electrical cables used for power distribution, control, and communication. Cable trays are used as an alternative to open wiring or electrical conduit systems, and are commonly used for cable management in commercial and industrial construction. They are especially useful in situations where changes to a wiring system are anticipated, since new cables can be installed by laying them in the tray, instead of pulling them through a pipe.
According to the National Electrical Code standard of the United States, a cable tray is a unit or assembly of units or sections and associated fittings forming a rigid structural system used to securely fasten or support cables and raceways.
