How to Install Cable Trays According to NEC Article 392
Nec Article 392 Pdf Download: Everything You Need to Know About Cable Tray Systems
Cable tray systems are a common and effective way to support and organize cables and raceways in various applications. They are used to distribute power, communication, control, and signaling circuits in industrial, commercial, and residential settings. Cable tray systems can offer many benefits, such as safety, dependability, space savings, and cost savings.
Nec Article 392 Pdf Download
However, cable tray systems also have to comply with certain codes and standards to ensure proper installation and operation. One of the most important sources of guidance for cable tray systems is the National Electrical Code (NEC), which is adopted in all 50 states and sets the minimum requirements for safe electrical design, installation, and inspection.
In this article, we will provide an overview of NEC Article 392, which covers cable tray systems in detail. We will explain the scope, definitions, uses permitted, uses not permitted, wiring methods and cable types, installation requirements, grounding and bonding requirements, and markings and identification requirements of NEC Article 392. We will also provide a link to download the full text of NEC Article 392 in PDF format for your convenience.
Scope and Definitions of NEC Article 392
NEC Article 392 applies to cable tray systems, including ladder, ventilated trough, ventilated channel, solid bottom, and other similar structures. It does not apply to conduit or tubing systems, wireways, auxiliary gutters, surface metal raceways, surface nonmetallic raceways, or busways.
A cable tray system is defined as a unit or assembly of units or sections and associated fittings forming a structural system used to securely fasten or support cables and raceways. Cable trays are not intended to be used as raceways themselves.
Uses Permitted and Uses Not Permitted of NEC Article 392
Cable tray systems are permitted to be used as a support system for service conductors, feeders, branch circuits, communications circuits, control circuits, and signaling circuits. Cable tray installations are not limited to industrial establishments.
Cable tray systems are not permitted to be used where subject to severe physical damage or corrosive conditions that are known to exist. They are also not permitted to be used where prohibited by other articles of the NEC.
Wiring Methods and Cable Types of NEC Article 392
The wiring methods and cable types that are permitted to be installed in cable tray systems are listed in Table 392.10(A) of the NEC. They include armored cable (Type AC), CATV cables, Class 2 and Class 3 cables, communications cables, communications raceways, electrical metallic tubing (Type EMT), electrical nonmetallic tubing (Type ENT), fire alarm cables (Type FPL), flexible metal conduit (Type FMC), intermediate metal conduit (Type IMC), liquidtight flexible metal conduit (Type LFMC), liquidtight flexible nonmetallic conduit (Type LFNC), metal-clad cable (Type MC), mineral-insulated metal-sheathed cable (Type MI), multiconductor control or signal cables (Type ITC), nonmetallic-sheathed cable (Type NM), power-limited circuit cables (Type PLTC), power-limited fire alarm cables (Type PLFA), power-limited tray cables (Type PLTC), rigid metal conduit (Type RMC), rigid polyvinyl chloride conduit (Type PVC), service-entrance cable (Types SE and USE), shielded nonmetallic-sheathed cable (Type SNM), underground feeder and branch-circuit cable (Type UF).
The wiring methods and cable types that are permitted to be used in any industrial establishment where only qualified persons service the installed cable tray system are listed in Table 392.10(B) of the NEC. They include single-conductor cables that are 1/0 AWG or larger and marked for use in cable trays; welding cables; single conductors used as equipment grounding conductors; single- and multiconductor medium-voltage cables that are Type MV; single- and multiconductor optical fiber cables; single- and multiconductor power-limited circuit cables that are Type PLTC; single- and multiconductor remote-control or signaling cables that are Type TC-ER; single- or multiconductor shielded power-limited circuit cables that are Type PLTC-ER; single- or multiconductor shielded remote-control or signaling cables that are Type TC-ER-JP.
Installation Requirements of NEC Article 392
Cable tray systems must be installed as a complete system with proper electrical continuity and support for the cables. Field bends or modifications must be made so that they do not impair the strength or performance of the cable tray system. Cable tray systems must be securely fastened to the building structure by suitable means at intervals not exceeding 3 m (10 ft). Cable tray systems must be permitted to have mechanically discontinuous segments between cable tray runs or between cable tray runs and equipment.
Cable trays must be completed before any cables are installed in them. Cables must be securely fastened to the cable trays at intervals not exceeding 1.5 m (5 ft). Cables must be arranged so that they do not obstruct access to other cables or equipment. Cables must have sufficient slack to prevent damage from vibration or movement. Cables must have adequate clearance from sharp edges or projections.
Grounding and Bonding Requirements of NEC Article 392
Metallic cable trays must be effectively grounded in accordance with Article 250 of the NEC. Metallic cable trays must also be bonded at each splice plate connection by means of mechanical connectors or bonding jumpers sized in accordance with Table 250.122 of the NEC.
Nonmetallic cable trays must have an equipment grounding conductor installed within or supported by the cable tray system throughout its entire length. The equipment grounding conductor must be sized in accordance with Table 250.122 of the NEC.
Markings and Identification Requirements of NEC Article 392
Cable trays and their associated fittings must be identified for their intended use by means of markings on the product or on a tag attached to it. The markings must include the manufacturer's name or trademark; the type designation; the material composition; the load rating; the maximum rung spacing for ladder-type cable trays; any special features such as corrosion resistance or fire resistance.
Cables installed in cable trays must also be identified by means of markings on their surface or on a tag attached to them. The markings must include the type designation; the voltage rating; the temperature rating; any special features such as sunlight resistance or flame retardance.
Nec Article 392 Pdf Download Link
If you want to download the full text of NEC Article 392 in PDF format for your reference, you can use this link: https://www.nfpa.org/-/media/Files/Codes-and-Standards/NEC/NEC-PDFs/NEC2020_Chapter_3_Wiring_Methods_and_Materials.pdf
Benefits of Cable Tray Systems of NEC Article 392
Cable tray systems have many advantages over other wiring methods, such as conduits or wireways. Some of the benefits of cable tray systems are:
Safety: Cable tray systems provide a safe and reliable way to support and protect cables and raceways from mechanical damage, fire hazards, and electrical faults. Cable tray systems also allow easy access and inspection of cables and raceways, which can prevent potential problems and reduce maintenance costs.
Dependability: Cable tray systems offer a high degree of flexibility and adaptability for changing or expanding electrical needs. Cable tray systems can accommodate various types and sizes of cables and raceways, and can be easily modified or extended to suit different applications. Cable tray systems also provide a stable and continuous support for cables and raceways, which can improve their performance and longevity.
Space Savings: Cable tray systems can save valuable space in buildings and structures by allowing cables and raceways to be installed in compact and efficient ways. Cable tray systems can be installed horizontally, vertically, or at any angle, and can follow the contours of walls, ceilings, floors, or roofs. Cable tray systems can also reduce the number of fittings and junction boxes required for cable connections.
Cost Savings: Cable tray systems can reduce the initial and operational costs of electrical installations by simplifying the design, installation, and maintenance of cables and raceways. Cable tray systems can reduce the labor and material costs associated with conduit or wireway installations, as well as the costs of cable splicing, termination, testing, and troubleshooting.
How to Download NEC Article 392 in PDF Format
If you are interested in learning more about NEC Article 392 and its requirements for cable tray systems, you can download the full text of NEC Article 392 in PDF format from the official website of the National Fire Protection Association (NFPA), which is the publisher of the NEC.
To download NEC Article 392 in PDF format, you need to follow these steps:
Go to https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=70, which is the webpage for NFPA 70: National Electrical Code.
Click on the "Free Access" button on the right side of the page.
Select the edition of the NEC that you want to download from the drop-down menu. The latest edition is 2023.
Click on the "View" button to open the online version of the NEC.
Navigate to Chapter 3: Wiring Methods and Materials, which contains NEC Article 392: Cable Trays.
Click on the "Download PDF" button on the top right corner of the page.
Save the PDF file to your device or print it out for your reference.
Cable tray systems are a versatile and efficient way to support and organize cables and raceways in various electrical applications. They offer many benefits, such as safety, dependability, space savings, and cost savings. However, cable tray systems also have to comply with NEC Article 392, which sets the minimum requirements for their installation and operation. NEC Article 392 covers the scope, definitions, uses permitted, uses not permitted, wiring methods and cable types, installation requirements, grounding and bonding requirements, and markings and identification requirements of cable tray systems. You can download the full text of NEC Article 392 in PDF format from the NFPA website for your reference.
We hope this article has helped you understand the basics of NEC Article 392 and its implications for cable tray systems. If you have any questions or comments, please feel free to contact us. Thank you for reading. 4e3182286b