How are the vertical shaft distribution boxes divided

Vertical shaft distribution boxes are divided based on the type of rising mains, load requirements, and building design, including single rising main, grouped supply, individual floor supply, ring main, and double feed systems.

Overview of Vertical Shaft Distribution

Vertical shafts, also called risers, are dedicated conduits or shafts in buildings that carry electrical cables and other utilities from the main supply to each floor . In large buildings, the vertical supply system (rising mains) is a key part of the electrical distribution network, connecting the main low-voltage or high-voltage boards to floor-level distribution boards . The arrangement of these shafts depends on the building size, shape, and load distribution, and must be coordinated with architectural design to ensure proper cable routing and safety .

Types of Vertical Shaft Distribution Boxes

1. Single Rising Main: A single vertical main cable or bus duct runs through the shaft, supplying all floors. It is simple and cost-effective, but a fault affects all floors, offering low supply security .

2. Grouped Supply: Floors are divided into groups, each served by a separate vertical main. This balances loads within each group and limits the impact of faults to a few floors .

3. Individual Floor Supply: Each floor has its own dedicated vertical supply from the main board. This provides higher reliability and easier maintenance but requires larger shafts and more complex installation .

4. Ring Main Supply: Vertical shafts are connected in a loop, allowing power to flow from multiple directions. This enhances supply security and reduces downtime during maintenance .

5. Double Feed Supply: Two independent vertical mains feed the same floors, often from separate substations. This is used in critical buildings where uninterrupted power is essential .

Design Considerations

• Load Distribution: The type of vertical shaft division depends on the load concentration per floor and the importance of supply security .
• Shaft Size: Must accommodate cables, bus ducts, ladders, and ventilation, with sufficient clearance for safety and maintenance .
• Transformer Placement: Transformers may be installed at the ground floor, intermediate floors, or top floors to bring high-voltage supply closer to load centers .
• Safety and Maintenance: Proper shaft design ensures easy inspection, maintenance, and future upgrades without disrupting building operations .

Summary

Vertical shaft distribution boxes are strategically divided to optimize load balancing, reliability, and maintenance. The choice of single, grouped, individual, ring, or double feed systems depends on building height, load density, and the required level of supply security. Proper planning ensures efficient power distribution while minimizing the risk of outages and facilitating safe operation .