Cable trays especially
perforated cable trays
and baskets are designed to help support and
organize cable bundles along with ceilings or walls.
Cable tray systems
for running large amounts of power or data cables above or below ground. Hutaib Electricals
types of cable trays
which have applications in different
Methods used for installation of cable trays are an important aspect for effectively using cable
tray systems. We have discussed below some basic standards and guidelines to follow while installing
cable tray supports at various locations.
In case you have not checked our
part 1 of this blog. Have a look at it before reading below.
Horizon Tee Support: NEMA Standard
Support holders for horizontal T-mount accessories must be placed no more than 610mm (24″) from
each end of the accessory on the supplied ladder. The conduit must also be supported once on
each side rail. For tees with a radius of 305mm (12), support position no more than 610mm (24)
from each end of the attachment on the included ladder.
Horizon Cross Support: NEMA Standard
Support Holders for crosshairs shall be located no more than 610mm (24 ″) from each end of the
connector on the supplied ladder.
The fitting conduit must also be supported once on each side rail. For a 305mm (12) radius
cross, place the brackets no more than 610mm (24 ″) from each end of the fitting on the supplied
Reducer Support: NEMA Standard
Fix the horizontal supports (2) at a distance no more than 610 mm (24″) from each of the ends.
Horizontal Y Support: NEMA Standard
Locate horizontal supports at a distance no greater than 610 mm (24″) from each of the three
openings and at the center of the fitting at 22.5°.
Vertical Inside / Outside Support: NEMA Standard
Vertical cable tray elbows at the top of runs must be supported at each respective end. At the
bottom of runs, they should be supported at the top of the elbow and within 610 mm (24″) of the
lower extremity of the elbows. Both Inner and outer fittings should be additionally supported at
a distance no more than (24″) from each end.
Offset Reducing Connection & Tray to Box / Floor Connection:
Cable Tray Installation
Make sure that conductors, dimensions, heights and other accessories are leveled and coordinated
other utility equipment.
The width of the cable tray/trunk/ladder should be wide enough to accommodate cables without
must allow for 25% clearance in the future. Cables should not be stacked.
If the conductors of the cable tray or ladder belong to different systems, the ELV and data
or have different insulation, the ladder or cable tray must be separated. Use insulation barriers
necessary. However, engineer approval is required.
Earth soil continuity must be ensured over the entire length of the tray and trunking.
Cable Tray Installation on Roof / Floor: Cable trays should not be placed directly on the ground or on the roof.
Cable trays installed on the roof must be supported by GI supports or concrete blocks.
It should be mounted far enough off the ground or roof to allow water to drain.
The cables must exit from the bottom of the cable tray.
When cable trays are installed on roofs or exposed to sunlight, factory-manufactured covers
should be installed to protect cables from direct sunlight.
Cable trays must be arranged so that the cover is always on top or on the side. The cover must
be secured to the trunking with a factory-fitted clamp.
The open ends of the tray/trough must be covered with a specially designed end cap.
Cable Tray Accessories: Where cutting of the trays is needed, round saws may be used. Different types of Cable tray
edges may be rasped or welded if it's far necessary, galvanized factors may be wiped clean then
is going to be sprayed with galvanizing spray immediately.
Cut part of trays and trunking, will be made free from sharp edges through submitting and
with zinc abundant and pinnacle coat and joined the usage of fish-plates with bolts and nuts.
Any slicing at the cable tray to be accomplished alongside the strong region and now no longer
throughout the perforation of the cable tray. Burrs want to be eliminated and cuts want to be
included with anti-rust galvanized paint to save you rust.
The minimal radius of the cable tray needs to be identical to the minimum bending radius of the
cables. Depending on the variety of cables to be located withinside the device it could be
to apply the following maximum radius.
Installation of Splice Connectors Splice couplers shall be positioned according to the manufacturer's recommendations.
Splice Joints should be designed and placed to maximize the rigidity of the cable tray.
Splice connections shall be secured with button/hexagon head bolts with nuts and washers
located on the outside of the tray or ladder unless otherwise specified by the manufacturer.
Thermal expansion splice joints should be installed wherever expansion joints are available.
All straight joints, elbow joints and offset couplings must be performed with care using
standard accessories (fish-plate and couplings). Only where it is not suitable should use
Cleaning of Work Area: After installation, there must be a visual inspection of the trunk line from the inside. This
is to ensure that it is free of debris, burrs, and litter.
There are no sharp edges that could damage the cable during installation.
Galvanized coating damaged by excessive roughing during transportation and erection should be
repaired using at least two coats of good quality zinc rich paint in accordance with BS 4652.
Upon completion of the installation of cable trays/trunks in an area, the completed work must be
presented for inspection and must be protected by the provision of a polythene cover.
Codes and Standards:
IS 4759: Hot-dip zinc coating on structural steel and other related products
IS 2629: Recommended practice for hot-dip galvanized iron and steel
IS 2633: Test method for uniformity of coating of zinc-coated products
IEC 61537: Cable Management Cable Tray System and Cable Ladder System
BS 4652: Specification for zinc-rich primer
National Electrical Manufacturers Association (NEMA) Standard