NEMA Standards Publication VE 2-2013 Cable Tray Installation Guidelines Endorsed by Cable Tray Institute www.cabletrays.com Published by: National Electrical Manufacturers Association th 1300 North 17 Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org © 2013 National Electrical Manufacturers Association.
NOTICE AND DISCLAIMER The information in this publication was considered technically sound by a consensus among persons engaged in its development at the time it was approved. Consensus does not necessarily mean there was unanimous agreement among every person participating in the development process. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document herein is one, are developed through a voluntary standards development process.
VE 2-2013 Page i CONTENTS Page FOREWORD ............................................................................................................................................... VII SECTION 1 SCOPE ...................................................................................................................................... 1 1.1 Scope ......................................................................................................................................... 1 1.2 General ........
VE 2-2013 Page ii SECTION 4 INSTALLATION OF CABLE .................................................................................................. 40 4.1 General .................................................................................................................................... 40 4.2 Handling and Storage .............................................................................................................. 40 4.3 Cable Tray Preparation ..............................................
VE 2-2013 Page iii Figure 3-9 Double Cable Tray Hanger ........................................................................................................ 10 Figure 3-10 Single Cable Tray Hanger ....................................................................................................... 10 Figure 3-11 Double Cable Tray Hanger ...................................................................................................... 10 Figure 3-12 Single Cable Tray Hanger .........................
VE 2-2013 Page iv Figure 3-46 Offset-Reducing Splice Plate ................................................................................................... 22 Figure 3-47 Vertical Support Plates ............................................................................................................ 23 Figure 3-48 Step-Down Splice Plates ......................................................................................................... 23 Figure 3-49 End Plate ...................................
VE 2-2013 Page v Figure 3-83 Barrier Strip Slice Barrier ......................................................................................................... 32 Figure 3-84 Barrier Strip Splice—Installed.................................................................................................. 32 Figure 3-85 Ladder Drop-Out ...................................................................................................................... 32 Figure 3-86 Trough Drop-Out ........................
VE 2-2013 Page vi Figure A-12 Pan with Louvers ..................................................................................................................... 46 Figure A-13 Tray with Close Rung Spacing ................................................................................................ 46 Figure A-14 Wire Mesh ............................................................................................................................... 46 Figure A-15 Ventilated Bottom ....................
VE 2-2013 Page vii FOREWORD For Cable Tray Installers: NEMA VE 2-2013 (hereinafter referred to as NEMA VE 2) is intended as a practical guide for the proper installation of cable tray systems. Cable tray system design shall comply ® ® with National Electrical Code (NEC ) Article 392, NEMA VE 1, and NEMA FG 1 and follow safe work practices as described in NFPA 70E.
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VE 2-2013 Page 1 Section 1 SCOPE 1.1 SCOPE NEMA VE 2 addresses shipping, handling, storing, and installing cable tray systems and provides information on maintenance and system modification. 1.2 GENERAL WARNING!—Do not use a cable tray as a walkway, ladder, or support for people; cable tray is a mechanical support system for cables and raceways. Using cable trays as walkways can cause personal injury and can damage cable tray and installed cables.
VE 2-2013 Page 2 NOTE: The basic types of connectors include rigid, expansion, adjustable, and reducer. The term “splice” is also used in the industry to describe a connector. degrees Celsius (°C) degrees Fahrenheit (°F) electromagnetic interference (EMI) electrostatic discharge (ESD) equipment grounding conductor (EGC) fasteners: Screws, nuts, bolts, washers, rivets, spacers, pins, and other items used to connect and assemble cable tray systems.
VE 2-2013 Page 3 support: A component that provides a means for supporting a cable tray, including, but not limited to, cantilever bracket, trapeze, and individual rod suspension.
VE 2-2013 Page 4 NOTE: Referenced as NEC. NFPA 70E, Standard for Electrical Safety in the Workplace 1.4.1 1.4.1.1 Contacts ASTM International For information concerning ASTM, contact: ASTM International 100 Barr Harbor Drive, PO Box C700 West Conshohocken, PA, 19428-2959 www.astm.org 1.4.1.2 CSA Group For information concerning CSA Group (or CEC), contact: CSA Group 178 Rexdale Blvd. Toronto, ON Canada M9W 1R3 www.csagroup.org 1.4.1.
VE 2-2013 Page 5 Figure 1-1 Correct MNNNNOT CORR Figure 1-2 Not Correct—Except when Using Extended Forks for Skidded Bundles Small to medium size orders less than 600 meters (m) (2,000 feet (ft)) are generally shipped via common carrier, LTL in enclosed vans. If hand unloaded, workers should wear gloves. To prevent damage to cable tray, never pull cable tray from a truck trailer by chaining to the bottom rung and dragging cable tray out of the trailer (see Figure 1-3 and Figure 1-4).
VE 2-2013 Page 6 Section 2 STORAGE Hot dipped galvanized after fabrication (H.D.G.A.F.) (see ASTM A123) steel, aluminum, and stainless steel cable tray and fiberglass or other non-metallic cable tray can be stored outside without cover, but should be loosely stacked, elevated off the ground, and ventilated to prevent storage stain. If appearance is important, cable tray should be stored indoors to prevent water or other foreign materials from staining or adhering to cable tray.
VE 2-2013 Page 7 Section 3 INSTALLATION For Cable Tray Installers: NEMA VE 2 is intended as a practical guide for the proper installation of cable tray systems. Cable tray system design shall comply with NEC Article 392, NEMA VE 1, and NEMA FG 1, and shall follow safe work practices as described in NFPA 70E. These instructions and information are not intended to cover all details or variations in cable tray systems; nor are they intended to provide for every possible installation contingency.
VE 2-2013 Page 8 To speed the process of installing the trapeze hangers, some nuts may be pre-threaded onto the threaded rod to the approximate location where the nut will be needed. One method for pre-threading the nuts is to put the nuts onto the end of a piece of threaded rod, attach a drill to the threaded rod, and run the nuts up the rod while holding them with an open end wrench.
VE 2-2013 Page 9 Figure 3-2 C-Channel Support Figure 3-1 Strut Nut Figure 3-3 Strut Support Figure 3-4 Angle Iron Support Figure 3-5 Typical Strut Support Installation Figure 3-6 Strut (Exploded View) Figure 3-7 Hold Downs © Copyright 2013 National Electrical Manufacturers Association
VE 2-2013 Page 10 3.3.1.2 Hanger Rod Clamp For examples, see Figure 3-8 through Figure 3-12. To install: a) Thread nuts onto threaded rod approximately 225 mm (9 in) above the desired location for the bottom of the cable tray. b) Place a clamp around the side rail of the cable tray. c) Lift the entire cable tray section onto the threaded rod, running the threaded rod through the holes in the clamps.
VE 2-2013 Page 11 Figure 3-12 Single Cable Tray Hanger 3.3.1.3 Center Hung Support For examples, see Figure 3-13 and Figure 3-14. To install: a) Thread nut onto threaded rod approximately 225 mm (9 in) above the desired location for the bottom of the cable tray. b) Slide washer and support onto the threaded rod with upright tube going through the center of the cable tray section needing support. c) Place a square washer on the threaded rod and thread on the second nut.
VE 2-2013 Page 12 3.3.1.4 Single Channel Cable Tray Hanger For an example, see Figure 3-15. To install: a) b) c) d) e) Thread nut onto threaded rod to the height required. Place hanger on the threaded rod and follow with one nut. Run nut up the threaded rod until the bottom of the hanger is at the desired height. Run top nut down to tighten. Place channel on the hanger, and secure in place as necessary. Figure 3-15 Single Channel Hanger 3.3.1.
VE 2-2013 Page 13 a) b) c) d) e) Thread nut onto threaded rod to the height required. Place the hanger or cable tray on the threaded rod and follow with one nut. Run the nut up the threaded rod until the bottom of the hanger or cable tray is at the desired height. Run the top nut down to tighten. Place the cable tray in the hanger, and secure in place as necessary. Figure 3-17 Multiple Splice Support Figure 3-18 Rod through Spine Hanger Figure 3-19 Clevis Hanger 3.3.
VE 2-2013 Page 14 Figure 3-22 Fiberglass Cantilever Bracket Figure 3-23 Single-Rail Direct Wall Mount Figure 3-24 Single-Rail Clamp Wall Mount 3.3.3 Floor and Roof Installations For examples, see Figure 3-25 through Figure 3-27. Cable tray should not be laid directly on the floor or roof. It should be mounted far enough off the floor or roof to allow the cables to exit through the bottom of the cable tray.
VE 2-2013 Page 15 Figure 3-27 Single-Rail Floor Support 3.3.4 Vertical Installations Similar to horizontal-type applications, vertical cable trays should be adequately supported. For examples, see Figure 3-28 through Figure 3-31. The cable tray should be supported on both the left and right side rails to the wall or support structure with appropriate hold-down clamps.
VE 2-2013 Page 16 Figure 3-30 Vertical Threaded Rod Support 3.3.5 Figure 3-31 Vertical Gusset Cantilever Support Transverse Installations For examples, see Figure 3-32 and Figure 3-33. Similar to horizontal-type applications, transverse cable tray should be adequately supported. This is accomplished by securing the upper and lower rails to the wall or support structure with appropriate hold-down clamps.
VE 2-2013 Page 17 3.4 STRAIGHT SECTION INSTALLATION Use the torque data in Table 3-1 for fasteners. Follow the manufacturer’s recommendations for nonmetallic or non-ferrous fasteners. Torque values do not apply for hollow sections, such as tubes. Consult the manufacturer for recommendations. Table 3-1 Fastener Torque Inch: GRD. 2 UNC Size Ft-Lbs 1/4 – 20 4-6 3/8 – 16 17-23 1/2 – 13 42-56 Metric: Class 5.8 Size M8 x 1.25 M10 x 1.5 M12 x 1.78 N-m 14-16 26-33 45-58 NOTES: a) Threads are not lubricated.
VE 2-2013 Page 18 Figure 3-36 Cable Tray Installation Figure 3-35 Cable Tray Installation Place the next straight section across the next support, and attach it to the previous section with a pair of splice plates and hardware. The maximum tray overhang past the last support should not exceed 600 mm (2 ft). Splice plates should be placed on the outside of the cable tray, unless otherwise specified by the manufacturer, with the bolt heads on the inside of the cable tray (see Figure 3-37).
VE 2-2013 Page 19 Table 3-2 Maximum Spacing between Expansion Joints that Provide for 250 mm (1 in) Movement** Temperature Differential* Steel Aluminum Fiberglass °C (°F) m (ft) m (ft) m (ft) 14 28 42 56 70 83 97 (25) (50) (75) (100) (125) (150) (175) 156 78 52 39 31 26 22 (512) (256) (171) (128) (102) (85) (73) 79 40 27 20 16 13 11 (260) (130) (87) (65) (52) (43) (37) 203 102 68 51 41 34 29 (667) (333) (222) (167) (133) (111) (95) *Temperature differential is the difference in temperatu
CABLE TRAY TEMPERATURE AT TIME o o OF INSTALLATION (F OR C ) VE 2-2013 Page 20 Figure 3-40 Gap Setting of Expansion Splice Plate—25.4 mm (1 in) Gap Maximum* *For designs using 15.9 mm (5/8 in) maximum gap (typically non-metallic), multiply gap setting by 0.625. NOTE: For extended vertical runs, see Section 3.5.2 3.4.3 Vertical Adjustable Splice Plates For examples, see Figure 3-41 and Figure 3-42. For changes in vertical direction not requiring a radius, vertical adjustable splice plates can be used.
VE 2-2013 Page 21 Figure 3-41 Two-Bolt Vertical Adjustable Splice Plates 3.4.4 Figure 3-42 Single-Bolt Vertical Adjustable Splice Plates Horizontal Adjustable Splice Plates For changes in horizontal direction not requiring a radius, horizontal adjustable splice plates can be used. Supports should be located within 600 mm (2 ft) of each side of horizontal adjustable splice plates (see Figure 3-43).
VE 2-2013 Page 22 Figure 3-44 Cable Tray to Box/Floor Splice Plates 3.4.6 Figure 3-45 Cable Tray to Box Connector Offset-Reducing Splice Plates For immediate width changes, use offset-reducing splice plates. Supports should be located within 600 mm (2 ft) of each side of offset-reducing splice plates (see Figure 3-46): a) Use an offset-reducing splice plate with a standard splice plate to form an offset reduction. b) Use a pair of offset-reducing splice plates to form a straight reduction.
VE 2-2013 Page 23 3.4.7 Vertical Support Plates For an example, see Figure 3-47 . Use vertical support splice plates for additional support of extended vertical runs (see Section 3.3.4). 3.4.1 Step-Down Splice Plates For an example, see Figure 3-48. Use step-down splice plates when connecting cable trays of different heights.
VE 2-2013 Page 24 Figure 3-52 Horizontal Hub 3.5 Figure 3-53 Vertical Tee or 90° Connector FITTINGS INSTALLATION See Section 3.5.3 for single-rail and wire mesh cable trays. 3.5.1 Recommended Support Locations for Fittings Recommended support locations follow, unless otherwise recommended by the manufacturer. 3.5.1.1 Horizontal Elbow Support For an example, see Figure 3-54.
VE 2-2013 Page 25 3.5.1.3 Horizontal Wye Support For an example, see Figure 3-56. Place horizontal wye supports within 600 mm (2 ft) of each of the three openings connected to other cable tray items, and at the 22-1/2° point of the arc adjacent to the side branch. 3.5.1.4 Horizontal Cross Support For an example, see Figure 3-57. Place horizontal cross support within 600 mm (2 ft) of each of the four openings connected to other cable tray items for the 300 mm (12 in) radius.
VE 2-2013 Page 26 3.5.1.7 Vertical Cable Tray Tees For an example, see Figure 3-60. Vertical cable tray tees should be supported within 600 mm (2 ft) of each fitting extremity. Figure 3-60 Vertical Tee (Side View) 3.5.2 Extended Vertical Runs 3.5.2.1 Cable Support Fittings For examples, see Figure 3-61 and Figure 3-62. These fittings are recommended for use at the top of long vertical runs of heavy cable to support the cables. Figure 3-61 Vertical Cable Support 3.5.2.
VE 2-2013 Page 27 3.5.3 Recommended Support Locations for Single-Rail and Wire Mesh Cable Trays Single-rail and wire mesh cable trays have alternate support configurations. Consult the manufacturer for details. 3.6 FIELD MODIFICATIONS Eventually it will be necessary to field cut the cable tray because the length of the cable tray required will be less than standard length.
VE 2-2013 Page 28 Figure 3-65 Cutting with Hand-Held Hack Saw Figure 3-66 Cutting with Bolt Cutters For examples of correct cut, correct blades to use, and correct blade placement, see Figure 3-67 through Figure 3-69. Figure 3-67 Correct Cut Figure 3-68 Correct Blades to Use Figure 3-69 Correct Blade Placement For examples of incorrect cut, incorrect blades to use, and incorrect blade placement, see Figure 3-71 through Figure 3-72.
VE 2-2013 Page 29 Figure 3-70 Incorrect Cut 3.6.3 Figure 3-71 Incorrect Blades to Use Figure 3-72 Incorrect Blade Placement Drilling Holes for splice plates must be drilled in field-cut cable trays. The most common method of locating the hole positions is to use a splice plate as a template. Drill jigs (see Figure 3-73) are also available.
VE 2-2013 Page 30 After cutting or drilling fiberglass cable trays, seal the cut edges with the manufacturer’s recommended sealant. Other protective coatings that are cut or damaged must be touched up with compatible coatings. 3.6.5 Wire Mesh Fittings Fabrication For examples, see Figure 3-76. Fittings may be field-fabricated from straight sections on-site with an offset bolt cutter and wrench, or a high-speed grinder.
VE 2-2013 Page 31 Figure 3-77 Barrier Strip— Straight Section Figure 3-78 Barrier Strip— Horizontal Fitting Figure 3-79 Barrier Strip— Vertical Fitting Barrier strips are sometimes used to separate cables within a cable tray, as required by the NEC. For an example, see Figure 3-80.
VE 2-2013 Page 32 Figure 3-83 Barrier Strip Slice Barrier 3.7.2 Figure 3-84 Barrier Strip Splice—Installed Drop-Outs For examples, see Figure 3-85 through Figure 3-87. The drop-outs and drop-out bushings provide a smooth surface to protect the cable insulation as it exits the cable tray. Figure 3-85 Ladder DropOut 3.7.
VE 2-2013 Page 33 Figure 3-88 Cable Tray to Channel 3.7.4 Figure 3-89 Channel to Ladder Tray Bracket Conduit to Cable Tray Adaptors For examples, see Figure 3-90 through Figure 3-92. These adaptors provide for attachment of conduit that terminates at a cable tray run. If a connector is not listed, it provides only a mechanical, not an electrical, connection. To make an electrical connection, an equipment grounding conductor must be run from the conduit to the cable tray.
VE 2-2013 Page 34 Figure 3-93 Cable Tray Covers Covers are typically added to a cable tray system when additional cable protection is required. It is important to consider that tray-rated cables have mechanical and UV protection built into their construction, making the sound use of covers uncommon. It is recommended to install covers the first six feet of a cable tray system extending vertically from a floor penetration.
VE 2-2013 Page 35 Figure 3-94 Cable Tray Cover Clamps and Accessories NOTE: Special consideration should be given to wind loading on outdoor applications. Table 3-3 provides information on the required spacing for cover clamps. Table 3-3 Quantity of Standard Cover Clamps Required Straight section, 1.8 m (6 ft) Straight section, 3.0 m (10 ft) and 3.
VE 2-2013 Page 36 For specific areas requiring bonding for electrical continuity, refer to Figure 3-95 through Figure 3-98. 3.8.1 Cable Tray Used as an Equipment Ground Conductor (EGC) For examples, see Figure 3-95 through Figure 3-98. Aluminum and steel cable tray, fittings, and connectors are permitted to be used as an EGC in accordance with NEC Article 392.60 under the conditions specified, if classified and marked with the cross-sectional area.
VE 2-2013 Page 37 clamp should be used on each section of cable tray. Install a wire-type EGC or bonding jumper at areas where: a) the cable tray is not mechanically continuous, or b) non-classified connectors are installed, or c) gaps surpass the length of traditional bonding jumpers. Figure 3-99 Grounding Clamps Bare copper wire-type EGC should not be used in or on aluminum cable tray. Bonding jumpers are not required if the wire-type EGC is properly bonded to all equipment. 3.8.3 3.8.3.
VE 2-2013 Page 38 Table 3-4 Metal Area Requirements for Cable Tray Systems Used as Equipment Grounding Conductors (NEC Table 392.60(A)) Maximum Fuse Ampere Rating, Circuit Minimum Cross-Sectional Area of Metal* Breaker Ampere Trip Setting, or Circuit Steel Cable Trays Aluminum Cable Trays Breaker Protective Relay Ampere Trip Setting for Ground-Fault Protection of Any 2 2 2 2 mm in mm in Cable Circuit In the Cable Tray System 60 129 0.20 129 0.20 100 258 0.40 129 0.20 200 451.5 0.70 129 0.20 400 645 1.
VE 2-2013 Page 39 Table 3-5 Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment (NEC Table 250.122) Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc., Not Exceeding(Amperes) 15 20 60 100 200 300 400 500 600 800 1000 1200 1600 2000 2500 3000 4000 5000 6000 * See installation restrictions in NEC Article 250. 3.8.
VE 2-2013 Page 40 Section 4 INSTALLATION OF CABLE The NEMA 5CT Cable Tray Section acknowledges input provided by NEMA wire and cable manufacturers to Section 5. 4.1 GENERAL This section offers some general guidelines or rules of thumb on installing cable in cable tray. This information is not intended to replace the recommendations of the cable manufacturer. The manufacturer of the product is the best source for information on the product, its use, and installation practices. 4.
VE 2-2013 Page 41 sufficient diameter prevent pinching the cable between the pulley flanges. Maintain each cable’s minimum bending radius to prevent damage to the cable. Contact the cable manufacturer for the proper minimum bending radius. Multiple pulling tools may be required at one bend to maintain this radius. Be careful with the entry and exit angle of the cable at the pulling tool, as this angle can exceed the bending radius.
VE 2-2013 Page 42 basket grip should be removed and all cable ends resealed to prevent moisture from entering the cable (see Figure 4-4 through Figure 4-6). Figure 4-2 Pulling Eye Figure 4-4 Straight Roller (Top Mounted) 4.6 Figure 4-3 Pulling Bolt Figure 4-5 Triple Pulley Guide Figure 4-6 90° Roller FASTENING CABLES a) Cables may be fastened to the cable tray by means of cable clamps or cable ties (see Figure 4-7 and Figure 4-8). Generally, cables are fastened every 450 mm (18 in) on vertical runs.
VE 2-2013 Page 43 Figure 4-7 Cable Ties—Vertical Application 4.7 Figure 4-8 Cable Ties—Horizontal Application PROTECTING INSTALLED CABLE Once the cable is installed in an open cable tray system, take care to protect the exposed cables from falling objects or debris that could cause damage to the cable. In areas where the cable tray is to be covered, covers should be installed as soon as possible.
VE 2-2013 Page 44 Section 5 MAINTENANCE WARNING—No electrical apparatus should be worked on while it is energized. When it is necessary to work in the vicinity of energized cables, all safety precautions should be followed, such as described in NFPA 70E. If cables are to be touched or moved, they should be de-energized. 5.
VE 2-2013 Page 45 ANNEX A TYPICAL CABLE TRAY TYPES Annex A provides examples of typical cable tray types. A.1 CABLE LADDERS For examples of cable ladders, see Figure A-1 through Figure A-3. Figure A-1 I-Beam Figure A-2 C-Channel Flange In Figure A-3 C-Channel Flange Out A.2 SINGLE-RAIL CABLE TRAYS For examples of single-rail cable trays, see Figure A-4 through Figure A-6.
VE 2-2013 Page 46 A.3 SOLID-BOTTOM CABLE TRAYS For examples of solid-bottom cable trays, see Figure A-7 through Figure A-10. Figure A-7 Pan Flange In Figure A-8 Pan Flange Out Figure A-10 Solid Sheet on Top of Ladder Rung Figure A-9 Corrugated Bottom A.4 TROUGH (VENTILATED CABLE TRAYS) For examples of trough (ventilated cable trays), see Figure A-11 through Figure A-13. Figure A-11 Corrugated Bottom with Holes Figure A-12 Pan with Louvers Figure A-13 Tray with Close Rung Spacing A.
VE 2-2013 Page 47 A.6 CHANNEL CABLE TRAYS For examples of channel cable trays, see Figure A-15 and Figure A-16.
