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1、Standard for Installing Metal CableTray Systems NECA/NEMA 105-2007 Published by National Electrical Contractors Association Jointly developed with National Electrical Manufacturing Association A M E R I C A N N A T I O N A L S T A N D A R D Standard for Installing Metal Cable Tray Systems NECA/NEMA
2、105-2007 An American National Standard Developed by National Electrical Contractors Association Developed by National Electrical Manufacturers Association Approved by Cable Tray Institute This standard is also published as NEMA VE 2-2006 2006 National Electrical Manufacturers Association NOTICE OF C
3、OPYRIGHT This document is copyrighted by NECA Reproduction of these documents either in hard copy or soft (including posting on the web) is prohibited without copyright permission. For copyright permission to reproduce portions of this document, please contact NECA Standards “ft” denotes foot; “lb”
4、denotes pound; “mm” denotes millimeter; “kg” denotes kilogram; “m” denotes meter; “N” denotes newtons; “F” denotes degree Fahrenheit; “C” denotes degree Celsius. -,-,- VE 2-2006 Page 1 Section 1 GENERAL WARNING!Do not use a cable tray as a walkway, ladder, or support for people; cable tray is a mech
5、anical support system for cables and raceways. Using cable trays as walkways can cause personal injury and also damage cable tray and installed cables. Hazardous voltages in electrical equipment can cause severe personal injury or death. Safety related work practices, as described in NFPA 70E, Part
6、11, should be followed at all times. The performance of a cable tray wiring system is dependent on its proper installation, including supports and cables. Neglecting installation and maintenance guidelines may lead to personal injury as well as damage to property. Installation and maintenance of cab
7、le tray wiring systems shall be conducted only by qualified personnel. For the purposes of this guideline, a qualified person is one who is familiar with electrical construction. In addition, the person is: Trained and authorized to test, energize, clear, ground, tag, and lock out circuits in accord
8、ance with established safety practices. Trained in the proper care and use of protective equipment such as insulated rubber gloves, hard hat, safety glasses or face shields, dust mask, and flash resistant clothing in accordance with established safety practices. -,-,- VE 2-2006 Page 2 Section 2 RECE
9、IVING AND UNLOADING Cable tray is generally bundled and shipped via motor freight, except for export shipments that could be crated or loaded in containers. Accessories and small components are boxed and often skidded. Cable tray can be shipped via enclosed van, trailer, or flat bed trailer. Van tra
10、ilers are normally used for less than truckload (LTL) shipments. This method of shipment is most common and cost effective and offers maximum protection from the weather during shipment. LTL shipments should be hand unloaded unless provisions have been made with the cable tray manufacturer for forkl
11、ift unloading. Flat bed trailers are often used for full truckload shipments and when customers want side forklift unloading or sling unloading by crane. (Special care must be exercised using slings so cable tray is not crushed from the improper location and lifting by sling.) CORRECT NOT CORRECT MN
12、NNNOT CORR *Except when utilizing extended forks for skidded bundles Small to medium size orders less than 600m (2000 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 truck
13、trailer by chaining to bottom rung and dragging out of trailer. CORRECT NOT CORRECT Inventory all items immediately after unloading, using the manufacturers packing list. Note on the bill of lading any shortage or shipping damage for filing freight claim. -,-,- VE 2-2006 Page 3 Section 3 STORAGE Hot
14、 dipped galvanized after fabrication (H.D.G.A.F.) (see ASTM A 123) 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
15、appearance is important, cable tray should be stored indoors to prevent water or other foreign materials from staining or adhering to cable tray. Mill galvanized (see ASTM A 653) or electro-galvanized (see ASTM B 633) cable tray must be protected or stored in a well ventilated, dry location. Bare st
16、eel cable tray should receive a protective coating as soon as possible to prevent surface rust. PVC or painted cable tray should be protected and stored indoors if possible. Cable tray must be protected from scratching and marring of finish. Small accessories should be stored to prevent loss. Cable
17、tray should be stored away from high traffic areas. Cable tray should be stacked by width and type. -,-,- VE 2-2006 Page 4 Section 4 INSTALLATION For Cable Tray InstallersThis publication is intended as a practical guide for the proper installation of cable tray systems. Cable tray system design sha
18、ll 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 do not intend to cover all details or variations in cable tray systems nor provide for every possible installation contingency. Construction Exp
19、erienceIt is recommended that the work described be performed by qualified persons familiar with standard electrical construction practices, electrical equipment, and safety of electrical wiring systems. Cable Tray Installation Locations Where not allowed - Article 392 states that cable tray systems
20、 shall not be installed in hoist ways or where subject to sever physical damage. Metal cable tray systems may support conductor types allowed in certain areas to include environmental air and classified locations. The restrictions apply to the conductors being installed not the cable trays. Local co
21、des apply. Provide access - Cable tray systems are to be installed so they are accessible. If possible 300mm (12 inches) minimum should be left above or between installed systems to allow for cable installation and maintenance. In possible fire areas - Cable tray installations should avoid possible
22、fire areas. Should that not be possible and there are critical circuits involved, stainless steel cable tray and fire resistant cables should be considered. Wrapping the cable tray in a flame resistant blanket may create a cable-heating problem without a fire. Installing a physical fire shield benea
23、th the cable tray system may provide only limited improvement and create other issues. 4.1 COMMON TOOLS FOR INSTALLATION The following tools are commonly used for installation of cable tray: Metal cutting saw Leveling device Touch-up material Tape measure Screwdriver Square Drill with bits C-clamp F
24、ile Torque wrench Open end wrench Ratchet wrench Nylon cord or laser Offset Bolt cutters (Wire mesh) Sealant for cut edges (Fiberglass) Dust Mask (Fiberglass) Cutting Saw (Fiberglass) Carbide or Diamond Tipped Appropriate safety equipment 4.2 SUPPORT INSTALLATION Caution! Do not cut or drill structu
25、ral building members (e.g. I-beams) without approval by the general contractor. -,-,- VE 2-2006 Page 5 In order to install the cable tray supports, first find the required elevation from the floor to the bottom of the cable tray and establish a level line with a laser or a nylon string. A string wor
26、ks well because it can be used to align the threaded rods on one side of a trapeze and find the tops of the supports. In order 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 met
27、hod 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 holding onto them with an open-end wrench. NOTENonmetallic supports and hardware may require special load bearing considerations due to material
28、composition and application temperature. Consult the cable tray manufacturer for recommended practices. 4.2.1 Cable Tray Supports Caution! Supports for cable trays should provide strength and working load capabilities sufficient to meet the load requirement of the cable tray wiring system. Considera
29、tion should be given to the loads associated with future cable additions (see section 6.3) or any other additional loads applied to the cable tray system or the cable trays support system. NOTENonmetallic supports and hardware may require special load bearing considerations due to material compositi
30、on and application temperature. NOTESpecial consideration may be required for center-supported systems considering eccentric loading. NOTEInstallations requiring seismic considerations affects the cable tray systems supports. The supports should be braced according to the affecting seismic zone. Con
31、tact the manufacturer for approved bracing information. 4.2.1.1 Trapeze Type (See Figures 4.1A through 4.1G.) To install: a. Thread nuts onto threaded rod approximately 50 mm (2 in.). above desired location for bottom of cable tray. b. Slide on square washers followed by cross member and second set
32、of square washers. c. Thread second set of nuts onto threaded rod. d. Move cross member so the top surface is located where bottom of cable tray run will be located. e. Move second set of nuts up threaded rod until cross member is reached and held in place. f. Make sure cross member is level, then m
33、ove first set of nuts down threaded rod until cross member is secured in place. In most cases, hold-down guide clamps may be mounted on either the inside or outside of the cable tray side rail. When installed on the inside of the cable tray, the clamp and/or attaching hardware should not extend abov
34、e the rung. VE 2-2006 Page 6 Figure 4.1A STRUT NUT Figure 4.1B C-CHANNEL SUPPORT Figure 4.1C STRUT SUPPORT Figure 4.1D ANGLE IRON SUPPORT Figure 4.1E TYPICAL STRUT SUPPORT INSTALLATION Figure 4.1F STRUT-EXPLODED VIEW VE 2-2006 Page 7 Figure 4.1G HOLD DOWNS 4.2.1.2 Hanger Rod Clamp (See Figures 4.2A
35、through 4.2E.) To install: a. Thread nuts onto threaded rod approximately 225mm (9 in.). above desired location for bottom of cable tray. b. Place clamp around side rail of cable tray. c. Lift entire cable tray section onto threaded rod running threaded rod through holes in clamps. d. Thread a secon
36、d set of nuts onto threaded rod moving them up until bottom of cable tray reaches desired location. e. Move first set of nuts down threaded rod and secure clamps in place. Figure 4.2A SINGLE CABLE TRAY HANGER Figure 4.2B DOUBLE CABLE TRAY HANGER VE 2-2006 Page 8 Figure 4.2C SINGLE CABLE TRAY HANGER
37、Figure 4.2D SINGLE CABLE TRAY HANGER Figure 4.2E SINGLE CABLE TRAY HANGER 4.2.1.3 Center Hung Support (See Figures 4.3A and 4.3B) To install: a. Thread nut onto threaded rod approximately 225mm (9 in.) above desired location for bottom of cable tray. b. Slide washer and support onto threaded rod wit
38、h upright tube going through center of cable tray section needing support. c. Place a square washer on threaded rod and thread on second nut. d. Move cross member so its top surface is located at the place where bottom of cable tray run will be located. e. Move second nut up threaded rod until it re
39、aches cross member and holds it in place. f. Move first nut down threaded rod until it secures cross member in place. VE 2-2006 Page 9 In most cases, hold-down/guide clamps may be mounted on either the inside or outside of the cable tray. When installed on the inside of the cable tray, the clamp and
40、/or attaching hardware should not extend into the cable pathway. Figure 4.3A CENTER HANGER SUPPORT Figure 4.3B CENTER HANGER SUPPORT 4.2.1.4 Single Channel Cable Tray Hanger (See Figure 4.4) To install: a. Thread nut onto threaded rod to height required. b. Place hanger on threaded rod and follow wi
41、th one nut. c. Run nut up threaded rod until bottom of hanger is at desired height. d. Run top nut down to tighten. e. Place channel on hanger and secure in place as necessary. Figure 4.4 SINGLE CHANNEL HANGER -,-,- VE 2-2006 Page 10 4.2.1.5 Double Channel Cable Tray Hanger (See Figure 4.5.) To inst
42、all: a. Thread nut onto threaded rod to height required. b. Place hanger on threaded rod and follow with one nut. c. Run nut up threaded rod until bottom of hanger is at desired height. d. Run top nut down to tighten. e. Place channels on hanger and secure in place as necessary. Figure 4.5 DOUBLE CH
43、ANNEL HANGER 4.2.1.6 Single Rail Cable Tray Hangers (See Figures 4.6A through 4.6C) To install: a. Thread nut onto threaded rod to height required. b. Place hanger or cable tray on threaded rod and follow with one nut. c. Run nut up threaded rod until bottom of hanger or cable tray is at desired hei
44、ght. d. Run top nut down to tighten. e. Place cable tray in hanger and secure in place as necessary. Figure 4.6A MULTIPLE SPLICE SUPPORT Figure 4.6B ROD THROUGH SPINE HANGER -,-,- VE 2-2006 Page 11 Figure 4.6C CLEVIS HANGER 4.2.2 Wall and Cantilever Brackets (See Figures 4.7A through 4.7E.) Secure t
45、he brackets to the structure making sure they are level and aligned with each other. Figure 4.7A SINGLE STRUT CANTILEVER BRACKET Figure 4.7B GUSSET CANTILEVER BRACKET Figure 4.7C FIBERGLASS CANTILEVER BRACKET Figure 4.7D SINGLE RAIL DIRECT WALL MOUNT -,-,- VE 2-2006 Page 12 Figure 4.7E SINGLE RAIL C
46、LAMP WALL MOUNT 4.2.3 Floor and Roof Installations (See Figures 4.8A through 4.8C.) 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. If strut is used for this purpose,
47、mount the strut directly to the floor or roofand attach the cable tray to the strut usinghold-down clamps and/or guide clamps. Figure 4.8A ELEVATED STRUT TYPE SUPPORT Figure 4.8B Figure 4.8C UNDERFLOOR SUPPORT ATTACHED SINGLE RAIL FLOOR SUPPORT TO FLOOR PEDESTALS -,-,- VE 2-2006 Page 13 4.2.4 Vertic
48、al Applications (See Figures 4.9A through 4.9D.) Figure 4.9A Figure 4.9B VERTICAL THREADED ROD SUPPORT VERTICAL GUSSET CANTILEVER SUPPORT Figure 4.9C Figure 4.9D VERTICAL STRUT SUPPORT VERTICAL WALL MOUNT 4.3 STRAIGHT SECTION INSTALLATION Use the torque data below for fasteners. Follow manufacturers recommendations for nonmetallic or nonferrous fasteners. Torque values do not apply for hollow sections such as tubes.