DID YOU KNOW that a cable tray in a Zone 1 classified area can itself become an ignition source if it is not correctly earthed and bonded? In a hydrocarbon-rich atmosphere, an unbonded metallic cable tray accumulates static charge from cable movement — and electrostatic discharge from the tray edge into the atmosphere is classified as a potential ignition source under IEC 60079-14 Cl. 9.3.4. This is not a theoretical risk. It is the reason Gulf EPC contractors and Saudi Aramco inspection teams check cable tray bonding drawings before almost any other document in the pre-construction package. Here is exactly what the standards require, what ARAMCO and Shell add, and what your documentation package must show.
Zone 1 vs Zone 2 — what changes in cable management requirements
Under IEC 60079-10-1: Zone 1 is where explosive atmosphere is occasionally present during normal operation; Zone 2 is where it occurs only in abnormal conditions. For cable management: in Zone 1, all metallic trays must be electrically continuous and bonded to the earthing system at every joint. A separate 4 mm² minimum copper bonding conductor must run across each tray coupler — standard bolt connections through coupler plates alone are not sufficient. In Zone 2 the same continuity requirement applies, but the inspection documentation standard is generally lower (project-specific). Cable trays are not classified as equipment under IEC 60079 and do not carry ATEX certification marks — they are passive components, and the compliance obligation is in installation method and earthing, not in the tray itself.
ARAMCO SAES-P-104 — what it adds beyond IEC
- Material: SAES-P-104 requires cable tray material in classified areas to be hot-dip galvanized mild steel or fibreglass (GRP). GRP is acceptable for instrumentation cable runs; HDG steel is the default for power and earthing runs.
- Fill ratio: SAES-P-104 specifies a maximum 50% fill for classified area trays — slightly more conservative than IEC 61537's 40% for ladder trays with power cabling.
- Support spacing: maximum 1,500 mm span between tray support brackets; 900 mm maximum for vertical runs. Structural calculations for cantilever brackets on spans exceeding 1,200 mm must be submitted for engineering review.
- Bonding: bonding conductors across every tray joint using stainless steel bonding links — not clip-type spring connections. MTC for the bonding wire must confirm minimum conductivity of 100% IACS.
- Vendor approval: for major ARAMCO projects, cable tray suppliers must be listed in or approved against ARAMCO SAES-A-004 (Approved Vendor List). This is project-specific pre-qualification, not a standing product approval — submit with engineering data sheets.
Shell DEP requirements — where they differ from IEC and ARAMCO
Shell DEP 33.64.10.10 (Engineering Line and Cable Routing) adds fire-load reduction requirements for classified areas. In practice: prefer open-rung ladder construction over enclosed trunking to reduce hydrocarbon pooling risk. Where Shell specifies GRP or aluminium for Zone 2 instrumentation runs: confirm with the project's designated authority — Shell local company authority (LCA) approvals override the generic DEP. For metallic trays in Shell Zone 1 projects: the same earthing bonding requirement applies as ARAMCO, plus Shell requires that tray support design accounts for fire deluge nozzle coverage — cable trays must not obstruct deluge nozzle spray patterns on process equipment.
The earthing specification that most EPCs miss
- Tray-to-earth connection: every cable tray run must be earthed at both ends — not just one end. For runs exceeding 30 m: intermediate earth connections at ≤30 m intervals.
- Bonding link specification: 4 mm² minimum copper bonding conductor across every joint. IEC 61537 Annex D covers bonding continuity — do not rely on coupler bolt connections alone.
- Earthing conductor beneath tray: per IS 3043 / IEC 62305-3, minimum 25×4 mm GI flat strip or 35 mm² stranded copper run continuously below the tray, bonded at each bracket attachment to the tray structure.
- Post-installation test: DC loop resistance test from the most remote tray section to the earthing grid should read <1 Ω. Document in the pre-commissioning test record — this is a standard requirement in ARAMCO, Shell and TotalEnergies handover packages.
Documentation package for a Gulf oil & gas project
- EN 10204 Type 3.1 MTC for structural steel (heat number, chemical analysis, mechanical properties — actual values, not 'complies').
- HDG coating inspection report: XRF or magnetic measurement per ASTM A123, minimum 5 readings per m², confirming ≥85 µm average.
- Dimensional inspection report: width, depth, sheet thickness, rung pitch against confirmed PO specification.
- Earthing bonding schedule: showing bonding conductor specification, joint type and installation interval for the project.
- COO and Preferential COO (CEPA/Saudi origin requirements as applicable).
- Packing list with heat number against every bundle — pre-shipment inspection can then verify physical goods match MTC before loading.
We have prepared cable tray documentation packages for ARAMCO, ADNOC and Shell EPC projects on multiple occasions. Submit your project specification number and we build the compliant document set — engineering data sheet, MTC format, coating report and COO — within 5 working days.