Installation Guide for Instrument Cables, Conduits and Cable TraysCONTROL SYSTEMS

References3DS-E53G-00001, Electrical Design Standard Conduit and Tray Notes, Symbols & Details EW-0000-501, Electrical Design Standard for Cable Installation Notes and Details BecWeb & Internet

DefinitionWhat is a Cable Tray?Assembly of units or sections and associated fittings forming a rigid structural system used to securely fasten or support cable and raceways.Why is Cable Tray?Cable trays are preferred in the areas with high cable density and scattered devices to be connected. The tray system also offers the flexibility of accommodating the minor device location changes.

Types of Cable TraysLadder TypeVentilated TroughSolid BottomChannel

Types of Cable Trays

Cable Tray StandardsThe National Electrical Code (NEC) publishes the standards for all types of electrical applications. Articles 318, 250 & 800 cover various aspects of cable tray systems.

NEMA (National Electrical Manufacturers Association) NEMA VE1, FG1 & VE2

Cable Tray StandardsNEMA VE1 covers general cable tray definitions, manufacturing standards, performance standards, test standards and application information NEMA FG1 addresses the standards for fiberglass cable tray systems NEMA VE2 is a cable tray installation guideline which covers receiving and unloading material, storage of material and general installation practices

Cable Tray Selection criteriaLadder Cable TrayMaximum strength for long span applications. Ladder cable tray is generally used in applications.

Solid Bottom Cable TrayNon ventilated continuous support for delicate cables. Solid Bottom cable tray is generally used for minimal heat generating electrical or telecommunication applications.

Cable Tray Selection criteriaTrough /Perforated Cable TrayTrough cable tray is generally used for moderate heat generating applications.

Channel Cable TrayUsed for cable drops and branch cable runs from the backbone cable tray system. Channel is used with limited numbers of cables where conduit is undesirable.

Channel Size & no. of Cables

Cable Tray routing design Choose the shortest feasible paths on major runs and provide good overall area coverage of equipment on all other runs.

Cable tray should be designed such that there is adequate structure available to support cable trays utilizing standard cable tray support details

Cable Tray Installation NotesTrays shall be kept a reasonable distance from heat sources like steam piping, steam generators & boilers etc. Trays shall be no closer than 12 above the top of hot pipe insulation on hot pipes 65C to 120C and 18 above the top of hot pipe insulation on hot pipes 121C to 260C.Instrument Cable Trays & Electrical Cable Tray shall be separated from each other based on low or high voltage.

Cable Tray Installation NotesWhen running parallel above pipes these distances should be further increased by 6.Cable trays shall be grounded in accordance with the Standard Grounding Notes.Cable trays shall be constructed of hot dipped galvanized after fabrication steel or aluminum.Ventilated or raised covers shall be used for power trays

Cable Tray Installation NotesTrays shall be inspected for burrs, sharp edges, or any other defects and such defects must be corrected before cable installation.After cable installation, covers shall be installed on each top tray in a stack, where the stack runs below floor gratings or in open areas subject to falling debris. Cable Tray support is designed on the basis of cable size, Cable Tray weight & cable weight.

Cable Tray Support System

Cable Tray Support System

Cable Tray Accessories

Cable Tray Joining plates

Cable StandardsNational Electrical Code (NEC)Institute of Electrical and Electronic Engineers - Standard 383American Petroleum Institute - RP 540 Recommended Practice for Electrical Installations in Petroleum Processing PlantsUnderwriters' Laboratories (UL)IEEE Standard No. 48 "IEEE Standard Test Procedures and Requirements for High Voltage Alternating Current Cable Terminations."IEEE Standard No. 422 "IEEE Guide for the Design and Installation of Cable Systems in Power Generating Stations."

Instrument Cable InstallationThe routing for all scheduled cables is given in the circuit Schedule and deviations from these routings are not permitted without prior approval from Engineering. Routing of non-scheduled cable is by construction.Cables shall be installed without splices. Splices, when required, shall be made in manholes or pull boxes. Splices shall not be pulled into raceways.

Instrument Cable InstallationCables shall not be installed in partially completed raceways. When field conditions dictates to do so, the responsible field engineer shall determine that completion of the raceways will not result in any damage to the installed cables.

Instrument Cable InstallationTie in cable to the tray bottom at approximately 6 feet intervals for horizontal & 5 feet on vertical cable tray runs.Cable shall be formed to avoid sharp bends over edges of conduit bushings upon entering or leaving boxes or cabinets.

Cable Tray StorageHot dipped galvanized (H.D.G.A.F.) steel, aluminum, and stainless steel cable tray and fiberglass or other non-metallic cable tray can be stored outside without cover.In that case, they should be loosely stacked, elevated off the ground, and ventilated to prevent storage stain. Mill galvanized or electro-galvanized cable tray must be protected or stored in a well ventilated, dry location.

Cable Tray StoragePVC or painted cable tray should be protected and stored indoors if possible.Cable tray must be protected from scratching and marring of finish. Cable tray should be stored away from high traffic areas

Cable Tray Safety NotesDo not use a cable tray as a walkway, ladder, or support. Using cable trays as walkways can cause personal injury and also damage cable tray and installed cables.The performance of a cable tray wiring system is dependent on its proper installation, including supports and cables.

Cable Tray Safety NotesInstallation and maintenance of cable tray wiring systems shall be conducted only by qualified personnel.Neglecting installation and maintenance guidelines may lead to personal injury as well as damage to property.

Cable Conduits

Standards for Conduit ANSI C80.1 - Galvanized rigid steel conduit.ANSI C80.3- Electrical metallic tubing.ANSI C80.5 - Aluminum rigid conduit ANSI C80.6 - Intermediate metal conduit NEMA TC-6 and TC-8 - Rigid nonmetallic conduit All conduits, with the exception of PVC duct type DB, shall be UL listed.

Cable Conduit Installation NotesConduit connections to any equipment subject to vibration shall be made with a flexible connection. The flexible conduit, when used at the end of a scheduled rigid conduit, will not be listed in the Raceway Schedule and shall be sized the same as the connecting rigid conduit. Conduits are available in different sizes. i.e. , 1, 1 , 2 & 3.Minimum length of flexible conduit shall be 12 for & 1 conduit, 18 for 1 & 2 conduit, and 24 for 3and above.

Conduits & Support

Cable Conduit Installation NotesConduit shall not have any welds applied to it.To ensure good ground continuity, conduit threads must be clean of any nonconductive coatings.Ends of all exposed conduit shall be plugged or capped during construction. All spare conduits shall be capped or plugged for future use.

Cable Conduit Installation NotesConduit type and size shall be identified in the circuit and raceway schedule. When a conduit is routed to a tray, it must be installed to the tray section specified in the circuit and raceway schedule. All conduits cut in the field shall be reamed and free of burrs before installation.