Cable bus systems are an integral solution for reliable power transmission in demanding industrial and utility environments. For applications up to 33 kV, they provide a safe, efficient, and flexible alternative to conventional bus ducts. Designed for both indoor and outdoor use, these systems are tailored to withstand the environmental extremes and electrical demands found in Saudi Arabia.

System Capacity and Configuration

Cable bus is engineered to carry substantial currents, ranging from 1200 A to 4000 A.

• Low-voltage systems: Up to 4000 A, typically using 7 conductors per phase.

• Medium-voltage systems: Up to 3150 A, typically using 5 conductors per phase.

Conductors are single-core cables with cross-sectional areas between 120 mm² and 400 mm², sheathed in non-metallic jackets. No splices or joints are permitted, ensuring mechanical and electrical integrity throughout the system.

Environmental and Operational Considerations

Saudi Arabia’s climate demands robust design. Cable bus systems must withstand:

• Outdoor pollution and dust with adequate shading.

• Temperature extremes: 50°C indoors without air conditioning, or 35°C indoors with cooling.

• Wind speeds up to 100 km/h in outdoor installations.

Outdoor shading structures should maintain a clearance of at least 150 mm above the cable bus enclosure, protecting cables from direct solar radiation.

Cable Specifications

All current-carrying conductors must be insulated with XLPE (cross-linked polyethylene) or EPR (ethylene propylene rubber). The insulation thickness must be appropriate to the system voltage, with a continuous operating temperature of 90°C, meeting the requirements of IEEE 835-1994, ICEA P-46-426, NEC, and IEC standards.

For low-voltage applications, cables must comply with IEC standards for XLPE/PVC, be flame-retardant, and must not include metallic sheaths or armoring.

Mechanical Supports and Stability

Intermediate cable supports should be fabricated from flame-retardant, non-tracking, moisture-resistant materials, such as molded glass-reinforced polyester or treated hardwood. Fiberglass support blocks are not acceptable.

Cable trays and supports must withstand 100 kA for 1 second of thermal and dynamic stress, ensuring stability during short-circuit events.

Enclosure Requirements

The cable bus enclosure serves as both protection and structural support. Key requirements include:

• Material: Non-magnetic stainless steel or aluminum alloy.

• Thickness: 3.2 mm for aluminum, 2.5 mm for stainless steel.

• Covers and base plates: 2 mm aluminum or 1 mm stainless steel.

• Ventilation: Openings must prevent the passage of rods larger than 6.35 mm.

All enclosures should be ventilated to dissipate heat. Fasteners must be manufactured from 300-series stainless steel to ensure corrosion resistance.

The structure is fabricated from extruded aluminum alloy 6063-T6, with allowable design stress not exceeding 10,000 PSI.

Accessories and Customization

Cable bus systems are delivered in tailored lengths, with welded aluminum housings designed for each installation. A complete package includes:

• Connectors, flanges, cable sealing kits, fire barriers, elbows, offsets, termination kits, and hardware.

• Detailed layout drawings with matching identification marks for fast, error-free installation.

For outdoor terminations, cable sealing fittings and non-magnetic end plates are required. Sealing ensures environmental protection and safeguards equipment.

Sealing and Fire Protection

To maintain safety and reliability, specialized sealing methods are essential:

• Water-tight flanges: RTV silicone sealant is applied to insulate conductors and provide a watertight barrier at wall or floor penetrations.

• MCT fire/water seals: Neoprene blocks installed after cable pulling, UL-listed for 2-hour fire resistance.

These methods guarantee environmental integrity, preventing moisture ingress and containing fire hazards.

Termination and Junction Boxes

Termination enclosures provide the space required to organize phases and connect conductors to equipment. Standard junction boxes are constructed from welded aluminum angle frames with bolted side plates and welded fixed panels.

For outdoor use, junction boxes must comply with NEMA 4 standards, featuring gasketed removable covers, fully welded panels, and sealed fittings to achieve a watertight design.

Conclusion

Cable bus systems in Saudi Arabia are governed by rigorous mechanical, thermal, and environmental requirements. With capacities up to 33 kV and 4000 A, robust enclosures, high-grade insulation, and strict sealing standards, these systems deliver unmatched reliability in harsh climates. Proper selection and adherence to specifications ensure longevity, safety, and efficiency in critical power infrastructure.