Designing Cable Tray Systems for UAE Summers: Heat Load, Expansion & Airflow Considerations

Cable tray design in the UAE cannot be treated as a fixed, one-time calculation. During the summer months, exposed metal is in continuous motion expanding under intense daytime heat, contracting after sunset, and repeating this cycle for weeks at a time. Systems that ignore this behaviour rarely age well and often show signs of stress far earlier than expected.

In UAE summer conditions, cable tray design comes down to three things: thermal movement, support restraint, and airflow. Miss one and the system starts to deform.

At BonnGulf, this is not a theoretical concern but a practical reality we account for in every design decision. We manufacture and supply cable tray systems used across rooftops, plants, data centres, and infrastructure projects in the region, and we work alongside cable tray manufacturers in uae who see the same patterns. What we see on site aligns closely with what standards and field data already tell us: heat load, thermal expansion, and airflow are the main drivers of long-term performance failures in cable tray installations.

Why Heat Is A Constant Factor

On UAE rooftops, surface temperatures of steel trays routinely exceed 50°C. Under direct solar radiation, they often climb higher. This matters because steel expands by roughly 12 micrometers per metre for every degree Celsius increase. Over a 40-metre run, a daily temperature swing from 20°C to 55°C produces close to 17 mm of linear movement. Aluminium trays experience nearly double that movement.

This expansion is not gradual over seasons. It happens every day. Designs that ignore this treat trays as fixed cable supports rather than long mechanical members under thermal stress. The result is predictable: bowed side rails, elongated bolt holes, cracked coatings, and misaligned supports.

Industry guidance already accounts for this. NEMA VE-1 limits continuous tray lengths between expansion joints to roughly 39 m for steel and 20 m for aluminium under a 55°C differential. Despite this, site audits across the UAE still show uninterrupted runs of 60–80 m, rigidly clamped at every support.

Why Expansion Joints Must Be Able To Move

Installing an expansion joint alone does not solve thermal movement. The joint must be part of a controlled movement system.

Each expansion zone requires one fixed anchor point. Other supports must guide the tray while allowing axial movement. Supports should be located close to either side of the expansion joint, typically within 600 mm.

When trays are rigidly clamped at every hanger, the expansion joint cannot function. Stress transfers into splice bolts and side rails instead. The tray “snakes” between supports, and the joint becomes the weak point rather than the relief point.

Field observations across GCC industrial projects show that most tray deformation issues originate not from missing expansion joints, but from incorrect restraint philosophy. The joint is present, but the system has nowhere to move.

How Heat Alters Tray Performance

High ambient heat also affects material stiffness. Steel loses measurable yield margin above 40 °C. Aluminium softens earlier. Manufacturer span tables, typically derived at 25–30 °C, become optimistic once trays are exposed to summer conditions.

In practice, experienced designers in the UAE shorten outdoor spans by 15–25%, especially for heavily loaded power trays. A ladder tray rated for a 3.0 m indoor span often performs more reliably at 2.2–2.5 m outdoors. Expansion joints should never coincide with maximum span midpoints, and splice locations perform better closer to quarter-span positions where bending stress is lower.

These adjustments are rarely mandated by code, but they show up consistently in post-installation inspections. Trays detailed with realistic outdoor spacing hold alignment longer and require fewer corrective works during the first years of operation.

How Airflow Affects Electrical Performance

Ambient heat is only one part of the problem. Cables also generate heat as they carry load. When trays are overfilled, airflow drops, cables derate faster, and insulation ages sooner.

In UAE conditions, conservative fill ratios are not wasted space. A 40–50% fill ratio allows heat to dissipate and leaves room for later circuits without forcing a reroute. Tray type matters. Ladder trays and wire mesh trays release heat effectively. Perforated trays offer a balance between support and ventilation. Solid-bottom trays, while useful for sensitive circuits, require careful derating when used for power cables in hot environments. Airflow is not a comfort issue. It directly affects current-carrying capacity and long-term reliability.

How Electrical Continuity Is Maintained During Movement

Thermal movement must never compromise earthing. Expansion joints interrupt metallic continuity and require bonding jumpers sized for full fault current, not just continuity checks.

This is frequently missed during extensions and retrofits. The joint is installed correctly, then someone adds a section later and assumes continuity still holds. In high-fault environments such as data centres, substations, and solar installations, undersized bonding across expansion joints becomes a latent safety risk. Bonding conductors should be selected to match the tray’s side-rail fault capacity, ensuring future circuit additions do not silently exceed grounding limits.

Why UAE Conditions Accelerate Failure

The UAE combines extreme daytime heat, rapid night-time cooling, direct solar exposure, and long unobstructed tray runs. This produces daily expansion–contraction cycles rather than seasonal ones. Fatigue accumulates faster. On poorly detailed rooftop runs, visible deformation often appears within a few years. Properly detailed systems routinely exceed ten years with minimal intervention.

Cable tray systems in this region must be treated as dynamic structures. Expansion joints, airflow, support spacing, tray selection, cable tray accessories, and bonding are interconnected design decisions. Addressed together, they reduce maintenance costs and extend service life. Addressed in isolation, they create systems that fight themselves.

At BonnGulf, we design and manufacture cable tray systems for these exact conditions. Heat is not an edge case here. It is the operating environment. Systems that allow controlled movement, manage heat load, and maintain airflow remain aligned, bonded, and serviceable long after the first summer has passed.