Wiring ducts are rigid trays typically used as raceways for cables and wires within electrical enclosures.
Wiring ducts, along with conduit, wireways, and cable carriers, are often used as basic components of a cable management system. The bulleted list below compares these components and their typical uses.
Wiring ducts are used to organize and protect cables within enclosures. They typically include features that allow cables and wires to be easily re-routed and terminated within the enclosure.
Wireways are enclosed, trough-like sections which protect cables from atmospheric contaminants. As such, they may carry a NEMA rating. Wireways are typically used in limited portions of a cable management system due to their relatively high cost.
Cable carriers are flexible, armored tunnels which protect cables during periods of continuous movement. They are frequently found in automation and material handling systems where moving machines are common.
Conduit is a tubular, metallic or non-metallic system designed to protect electrical wiring. The term "conduit" is typically used when referred to tubing systems which contain electrical power wiring.
Considering the above list, different means of cable and wire protection should be selected based on the intended environment, safety needs, as well as cable type and size.
Wiring ducts are generally available in two configurations: slotted (the wiring duct has slots or fingers for easy customization and breakout) and slotless (solid wiring ducts that do not have any fingers or slots).
Configuration is generally determined by the duct's intended application. For example, standard slotted ducts provide easy re-routing of terminated wires and provide ample cable support, while unslotted ducts provide overall cable protection in panels where breakouts are not required and cables are infrequently accessed. Thin slotted ducts allow easier cable access but offer less support than standard types.
(left to right) Slotted wiring ducts showing broken out wires; slotless duct.
As shown in the image below, slotted ducts often feature multiple upper and/or lower score lines which allow the fingers to permanently break away in various places. This attribute allows the customization of the wire slot size in order to break out thicker cables or groups of cables.
Slotted wiring ducts require decisions on slot pitch (the distance from one slot space center to the adjacent slot space center) and finger width (the measured width of wire duct fingers).
The manufacture and use of wiring ducts may be governed by various standards, codes, and certifications. Because wire ducts may contain electrical power wires, improper use or faulty production methods can cause wires to stretch or break during or after installation, leading to future failure or fires.
Common standards and codes which apply to wiring ducts are listed below. These are largely based on the international IEC 60364 standard for low-voltage wiring.
- NFPA 70 - 2013 National Electric Code (United States)
BS 7671 - IET Wiring Regulations (Great Britain and some former territories)
CSA C22.1 - Canadian Electrical Code
Steven Engineering / Panduit - Wire Duct (pdf)
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