Cooper Bussmann CT02MAN manual Installation. I Adequate Access

Accessible: (As applied to wiring methods) Capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building.

Reprinted with permission from NFPA 70-1999, the National Electrical Code®, Copyright© 1998, National Fire Protection Association, Quincy, MA 02269. This reprinted material is not the complete and official position of the National Fire Protection Association, on the referenced subject which is represented only by the standard in its entirety.

392.6. Installation. (I) Adequate Access.

Cable tray wiring systems should be designed and installed with adequate room around the cable tray to allow for the set up of cable pulling equipment. Also, space around the cable tray provides easy access for installation of additional cables or the removal of surplus cables. Where cable trays are mounted one above the other, a good rule to follow is to allow 12 to 18 inches between the underside and the top of adjacent cable trays or between the structure's ceiling and the top of the cable tray.

392.6.Installation. (J) Conduits and Cables Supported from Cable Tray.

For the 1996 NEC®, a significant change was made in this section. The installations covered in this section may now only be made in qualifying industrial facilities.

In Section 392.6(J) of the 1993 NEC®, cable tray installations that supplied support for conduits were not restricted to qualifying industrial facilities. The 1996 NEC®, Section 392.6(J) text restricts the use of such installations even though there is no documented history of problems in non-industrial installations.

As a result of the change in this section, identical functional installations in non-qualifying installations (commercial and industrial) and qualifying industrial installations have different physical requirements. In a qualifying industrial installation, a conduit terminated on a cable tray may be supported from the cable tray. In a commercial or non-qualifying industrial installation, the conduit that is terminated on the cable tray must be securely fastened to a support that is within 3 feet of the cable tray or securely fastened to a support that is within 5 feet of the cable tray where structural members don’t readily permit a secure fastening within 3 feet. The conduit of the non-qualifying installation still needs

to be bonded to the cable tray. A fitting may be used for this bonding even though it will not count as a mechanical support.

Over 99 percent of the conduits supported on cable trays are the result of conduits being terminated on the cable tray side rails [See Section 392.8(C)]. For over 40 years, it has been common practice to house the cables exiting the cable tray in conduits or cable channel where the distance from the cable tray system to the cable terminations requires the cable be supported. Several manufacturers supply UL approved cable tray to conduit clamps such as the B-Line 9ZN-1158.

In addition to conduit and cables being supported from cable tray; industrial companies have been mounting instrumentation devices, push buttons, etc. on cable tray and cable channel for over 40 years. This section once lead some to believe that only conduit or cables may be supported from cable trays which is not correct as cable tray is a mechanical support just as strut is a mechanical support. Because of this, the wording in Section 392.6(J) of the 2002 NEC® was changed. Instead of allowing only cable and conduit to be supported from cable tray, the code now states that raceways, cables, boxes and conduit bodies are now permitted to be supported from the cable tray. Where boxes or conduit bodies are attached to the bottom or side of the cable tray, they must be fastened and supported in accordance with Section 314.23.

Cable Tray Manual Cooper B-Line, Inc

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