HANDLE TRAYS (BANDEJAS PORTACABLES)

HANDLE TRAYS

The cable tray must be considered as a support element and not as a conduit, it can support conduits or certain conductors certified and labeled for use in trays, must meet the established installation requirements. In addition, they must meet the following requirements:

• Protection against corrosion,

• The manufacturer of cable trays must specify the maximum permitted mechanical stresses they can withstand, in any case, trays constructed of steel foil with a thickness less than 22 gauge or equivalent of 0.75 mm are not accepted.

• Cable tray fittings must be designed to carry out their cable support and securing function and must not present any sharp elements which could lead to insulation of the conductors.

• Non-metallic cable trays should be made of flame-retardant materials, non-fire propagators and low emission of toxic gases or corrosive substances.

• Electrical conductors with piping should not be installed in the same cable tray.

• Equipotential bonding must be ensured between the different sections of the tray.

• Cable on trays in residential installations and other exceptions defined in NTC 2050 is not permitted.

• Drivers to be installed must be certified and labeled for tray use and meet the installation requirements set forth in section 318 of NTC 2050. Not more than 40% of the fill volume of the power cable tray and Control or 50% for instrumentation cables, as established by the standards.

• The installation of conductors of gauges of less than 1/0 in cable trays may be accepted provided that they are of a cross section greater than or equal to 12 AWG, take account of temperature derating according to NTC 2431, Cables of 1/0 gauge greater than that of a wall that is compatible with that of the tray, the spacing between crossings or slats of the horizontal tray does not exceed 15 cm for conductors between 2 and 8 AWG and 10 cm for conductors between 10 and 12 AWG. This type of installation should not be handled by unqualified persons.

• Installations in metallic cable tray for some special installations

USES PERMITTED

Methods of wiring. The following wiring methods are permitted in cable tray systems:

• Cables with metallic coating and mineral insulation.

• Non-metallic folding electric pipes

• Shielded cables with metallic coating

• Non-metallic coated cables

• Multiconductor cables for connection

• Multiconductor sub feeder cables and branch circuits

• Power cable and control for trays

• Instrument Tray Cables

• Limited power cables for trays

• Other Multiconductor power cables, signals and control factory-mounted, specifically approved for installation in trays

• Intermediate metallic conduit tube

• Rigid metallic conduit tube

• Rigid non-metallic conduit tube

• Metal electrical piping

• Flexible metal tubing

• Flexible metallic conduit tube

•          Optical Fibre wires

• Flexible, liquid-tight metallic conduit and flexible, liquid-tight, non-metallic conduit.

 In industrial installations. It is allowed to use the installation methods, in any industrial establishment under the conditions established in their respective Sections.

Only in industrial installations, when the supervision and maintenance conditions ensure that the cable tray system is serviced only by qualified persons, it is possible to install in ladder trays, ventilated channel or ventilated vats.

• Single Conductor. The single conductor cable shall be 53,50 mm2 (1/0 AWG) or larger in cross-section and of a type certified and labeled on its surface for use in trays. When single cables with a cross section of 53.50 mm2 (1/0 AWG) to 107.21 mm2 (4/0 AWG) are installed in ladder type trays, the maximum separation of the steps must be 230 mm. If the cables are exposed to sunlight, they must be identified as being resistant to sunlight.

• Multiconductor. Multiconductor MV cables, when exposed directly to the sun, must be identified as resistant to sunlight.

• Equipment earthing conductors. Metal cable trays are permitted as equipment earthing conductors when their continuous maintenance and supervision ensure that the tray system will only be serviced by qualified personnel and that the cable tray

In hazardous locations (classified). Cable trays in hazardous locations

(Classified) shall only contain the types of cables permitted in Articles 501-4, 502-4, 503-3, and 504-20.

E) Cable trays, not of metal. Non-metallic cable trays are allowed to be used in corrosive areas and where voltage isolation is required.

CONSTRUCTION SPECIFICATIONS.

A) Strength and stiffness. The cable tray must have sufficient strength and rigidity to provide adequate support for all cables installed in them.

B) Rounded edges. The cable tray should have no sharp edges, burrs or protrusions that could damage the cable linings or insulation.

C) Protection against corrosion. The cable tray must be of a corrosion resistant material or, if they are of metal, be suitably protected against corrosion.

D) Side rails. The cable tray should have side rails or other

Structural members.

E) Hardware. The cable tray must have hardware or other suitable means to be able to change the direction and elevation of the cables.

F) Cable trays, not of metal. The non-metallic cable tray should be made of flame-retardant material.

INSTALLATION

A) Complete system. The cable trays must be installed forming a complete system. If they are made during the bend installation or modifications, they must be done in a way that maintains the electrical continuity of the cable tray system and the cable support. Cable trays are allowed to have mechanically discontinuous segments between the cable runs or between cables and equipment. The system must support the cables as established in the corresponding Sections.

B) Finished before installation. Each length of the cable tray must be terminated prior to cable installation.

C) Supports. When cables come from the tray to pipes or other enclosures, supports must be installed to avoid stresses on them.

D) Lids. For parts or sections where more protection is required, protective covers or enclosures of a material compatible with that of the cable tray should be installed.

E) Multiconductor cables with nominal 600 V or less. Multiconductor cables with nominal 600 V or less can be installed in the same tray.

F) Cables with more than 600 V nominal. Cables of more than 600 V nominal with other cables of 600 V nominal or less should not be installed in the same tray.

G) Through walls and partitions. Cable tray is allowed to be extended

Transversally through walls and partitions or vertically through floors and platforms in wet or dry places when installing.

H) Exposed and accessible. Cable trays must be exposed and accessible.

I) Adequate access. Around the cable trays should be left and maintained a sufficient space that allows adequate access for the installation and maintenance of cables.

J) Conduits and cables supported in the trays. In industrial installations, when supervision and maintenance conditions ensure that the cable tray system is serviced only by qualified personnel and the trays are designed so that they can withstand the load, conduit pipes and cables are allowed to be supported in the trays. A certified clamp or adapter must be used for the termination of the conduit tubes in the tray and no support shall be required less than 0.9 m. For tubes and cables that are parallel to the tray, next to it or below, the supports must meet the requirements established in the corresponding.