CABLE TRAY INSTALLATION PROCEDURE

This article is about cable tray installation as per international standard of NEMA VE1, NEMA VE2 and ARAMCO standards.

CABLE TRAY INSTALLATION PROCEDURE / METHOD STATEMENT

1. All cable trays & accessories received at site shall be inspected, handled and stored upon receipt in accordance with Project Procedure for Material Control.

2. Inspections shall be conducted by the Electrical contractor, Electrical QC Inspector and Company representative in accordance with Inspection & Test Plan (ITP) inspection test plan.

3. Cable trays and covers for electrical & instrumentation cables shall be manufactured from hot dip galvanized carbon steel matching to project requirement specifications.

4. Cable tray installation shall be self supporting type with a wide flange (48mm or 72mm or 100mm) in accordance with cable cross section.

5. Cable tray installation shall preferably be installed flat in buildings or operating structures.  Tray shall run as far as possible under flooring and walkways.  Only in special cases shall cable trays be installed vertically or on edge.  On vertical cable trays and on edgewise – horizontal cable trays, each cable shall be fixed with 20mm wide stainless steel strips (two per meter).  On horizontal cable trays, laid flat cables are fixed in group (one fastening for every two or three meters).  On pipe racks, cable tray shall run on the top most level(s).

6.  Cable trays shall be fixed onto standard steel shapes, welded to steel structures or fixed on to concrete structures with self-drilling dowels.  Distance between fixing points and cable tray support spacing shall be a maximum of three meter for ladder type tray and two meter maximum for perforated tray so as to avoid strain on cable trays.

7. Cable tray installation shall be designed to carry a load of 100kg/m. All cable trays shall be perforated or ladder type to avoid the retention of water and to allow fastening of the cables.

8.  Cable trays shall be provided with covers where there is high risk of mechanical damage during normal operation or maintenance periods.  Cover fabrication shall be the same as that of cable trays themselves and shall be fixed on cable trays with proper clips recommended by cable tray Manufacturer/Vendor and comply with project required specification.

9.  The number of single or multi-conductor cables rated 11kV, 6.6kV, 1kV or less in cable trays shall include an allowance of 20% extra space for future expansion.

10.  Separate racking/trays shall be installed for the following electrical systems, generally arranged top to bottom manner.
a.) HV and MV cables
b.) LV Power, Lighting and Control cables for non-instrument cables
c.) Instrument Cables (Electronic and Signal Cables)
d.) Telecommunication Cables

The cable tray system shall be installed in accordance with the project specification, manufacturer’s instruction and the referenced standard installations details.
Locate the area where cable tray shall be installed as per the Issued For Construction (IFC) drawings.

Prepare the required tools and materials to be used for the installation of the cable tray. Inspect tools for proper working condition.
Install cable tray supports for the stability of the cable tray.

Ensure sufficient space provided and maintained for cable tray to permit adequate access for installing & maintaining the cable.

Ensure that cable trays are exposed and accessible for installation.

Cable tray sections, fittings and connected raceways shall be bonded using bolted mechanical connectors or bonding jumpers.

Testing Procedure for cable tray

The test method shall be conducted for minimum requirements for the installation of cable tray system applied as follows:

• Testing of  Cable Tray installation
• Confirmation of materials to specifications and Issued For Construction (IFC) drawings.
• Visual inspection of finish/coating & dimensional check of cable tray width, rung space, height, & run length.
• Check all braces and supports are adequate to handle weight of the tray & cables in accordance with the detailed drawings.
• Inspect the installed supports to ensure that it is levelled and aligned vertically and the whole assembly is rigid.
• Check the expansion joints or connectors are properly installed.
• Check of cable tray installation if it does not conflict with other services or equipment.
• Where supports are bolted to structural steel, ensure that all bolts, nuts, etc. are correctly installed & securely fixed.
• Hold down clamps shall be installed properly and are anchored on required locations.
• Ensure no sharp edges & burr that would cut or damage the cables.
• All metallic cable tray systems shall be bonded at every 25m of length. Coupler plates or bonding jumpers shall be used with every section and across each tray joint to give electrical continuity.
• Earth bonding jumpers are checked for proper connection and bonded to main grounding grid.

Test results will be recorded on following basis.

1.   CHECK THE SIZE, MATERIAL AND ACCESSORIES AS PER ISSUED FOR CONSTRUCTION (IFC) DRAWINGS AND PROJECT SPECIFICATION REQUIREMENTS.
2.   CHECK FITTINGS, BENDS & SUPPORTS ARE CORRECTLY INSTALLED AS PER DRAWINGS/SPECIFICATIONS.
3.   CHECK PROPER SPACING OF SUPPORTS & CLEARANCES FROM OTHER STRUCTURE/EQUIPMENT OF CABLE TRAY/LADDER.
4.  VERIFY CORRECT ROUTING OF CABLE TRAY/LADDER AS PER ISSUED FOR CONSTRUCTION DRAWINGS.
5.  CHECK BONDING JUMPER & COVER WAS PROPERLY INSTALLED.
6.  ENSURE NO SHARP EDGES & BURR THAT WOULD CUT OR DAMAGE THE CABLES.
6.  CHECK EARTHING CONNECTION TO MAIN GRID & CONTINUITY OF CABLE TRAY/LADDER AS PER SPECIFICATION.
7. CHECK COMPLETE CABLE TRAY/LADDER SYSTEM INSTALLATION.

INTERNATIONAL REFERENCES FOR CABLE TRAY

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