11.8.1 Usage with Enclosed Electrical/Electronic Equipment
In certain locations, cable supports and/or enclosures are installed for dedicated use with enclosed electrical/electronic equipment. In such cases, the use of a cable/utility management system is a part of custom-made equipment (see Figure 11-6). It is acceptable for these cable/utility management systems to be used to support bundles of cables, hoses, and tubing that run from the equipment console to the unit under test.
In cable/utility management systems where cables (other than those of the custom equipment, exist) steps should be taken to ensure that no damage to the existing cables can occur, and that the collocation of the cables does not create additional hazards.
Fig. 11-6. Example of cable management in laboratory.
11.8.2 Requirements
1. The following requirements and recommendations relate to installation and use of utility cable tray systems:
a. Cable tray systems shall11.44 be grounded.
b. Cable tray systems shall11.44 be engineered and properly installed so as to preclude mechanical failure under anticipated load conditions.
c. Cable tray systems shall11.44 not have sharp edges.
d. Caution should be exercised when adding cables or other services to existing trays to insure that installed cables are not crushed, abraded, or otherwise damaged.
e. Mechanical fastening of cables to the cable tray structure or to other cables in the cable tray system should be minimized. Excessive fastening unnecessarily constrains the addition or removal of cables at future times. It is recognized, however, that mechanical fastening of certain cable installations is necessary to limit movements associated with EM forces.
f. It is recommended that all unused cables be removed from existing cable tray systems. It is recognized, however, that such removal may be precluded if existing operational cables would be adversely affected by the removal process.
g. Cable trays should not be utilized for storage of excessive lengths of installed cables.
Cables should be dressed to suitable lengths upon installation.
h. It is recognized that in many locations, due to limited space, the cable tray system offers the best means of bringing services to support experimental devices. In all
cases, neither the mechanical loading nor the ventilating capability of the installed cable tray system shall11.45 be significantly compromised by addition of such services.
i. Flammable gas lines shall11.46 not be permitted to be located in cable trays.
j. Utilization equipment should not be located in cable tray.
k. For instances of where premise wiring is to be installed in a utility cable tray, such wiring shall11.47 be installed in accordance with the NEC. The installation of premise wiring should be segregated through the use of tray dividers.
l. For installations of signal cable into a power cable tray, the responsible engineer should consider the cable for thermal and electrical properties in consideration of the specific installation and the cable tray for structural integrity. All installations in power cable tray shall11.48 follow the NEC guidelines for cable tray fill.
m. For installations of cable into a utility cable tray, the responsible engineer should take into account the structural load capability of the cable tray system and the durability of the existing cables. The nature of signal circuits is such that the energy carried by the cables is relatively low. Accordingly, the resultant losses in signal cables are of a sufficiently low level that heat dissipation is not a problem.
n. Non-flammable gas lines which are neatly bundled and secured shall11.49 not be installed in utility cable tray or attached to the utility cable tray supports (not attached to the tray itself).
o. Cable trays shall11.50 be made of corrosion-resistant material or adequately protected from corrosion that may be encountered in use. Refer to manufacturers’ literature.
p. Verify that the building structure has adequate capacity to support the fully loaded cable tray(s). An appropriate safety factor should be applied to account for stresses during installation of cables, stresses during seismic events, and uncertainties about the building structure.
q. Provide protection for cables from deteriorating agents (see NEC 392.5(C)).
2. The following requirements and recommendations relate to installation and use of cable tray systems in pulsed power applications:
a. Cable tray systems shall11.51 be grounded in a way such that inductive effects are minimized during a fault condition so that voltage rise along the ground path is also minimized.
b. The cable tray should be designed and installed to minimize inductive effects during a fault condition.
An assessment of any hazards identified with the equipment, as well as the operation in which it is involved, shall11.49 be performed to ensure the safe operation of components in the cable/utility management system.
Metallic cable/utility management systems that support electrical conductors shall11.51 be grounded or bonded to the equipment. A qualified worker should inspect all components with exposed metal parts to check for grounding integrity. This inspection should be documented.
When cable/utility management systems are installed exclusively for electrical/electronic equipment usage, and when these trays are metallic and not grounded or bonded, approved
documentation should exist stating the reason for not grounding or bonding the system. (See Section 11.3.)
Equipment cable/utility runs installed in cable/utility management systems should be visually inspected periodically. These inspections should be performed at the time of installation, and at any interval specified in the equipment documentation. Any inspection should, as a minimum, consist of:
1. A visual check for the integrity of cable jackets and visible shields;
2. A check for the integrity of all utility hoses by looking and listening for leaks;
3. A visual check on all securing devices used to hold the bundle on the tray to assure the bundle is positioned properly and no damage has occurred;
4. A visual inspection on all bends for signs of pinching, cutting, exceeding minimum cable bending radius, or other damage; and
5. Documentation of all results of any inspection.
Supports shall11.52 be provided to prevent stress and physical damage to cables where they enter or exit cable/utility management systems.