How to connect the vertical shaft cable trays

Vertical cable tray connections require careful planning, proper support, and safety measures to manage cable weight and prevent mechanical damage.

Planning and Layout

When connecting cable trays vertically, start with a main vertical riser in the shaft, from which horizontal branches can extend at each floor or equipment level. Horizontal runs typically begin with a downward bend from the vertical tray to allow cables to sweep smoothly onto the horizontal tray without sharp bends, maintaining the minimum bend radius for the cables ( ).

Support and Fixation

Vertical cable trays must be securely supported to handle the weight of the cables. Use center-hung supports, brackets, clamps, or cleats to maintain alignment and prevent sagging. Ladder-type trays are preferred for vertical runs because their rungs provide convenient anchor points for tying down cables and maintaining position ( ). Maximum support spacing should follow manufacturer guidelines, typically around 3.6 meters for heavy loads ( ).

Cable Handling and Safety

Cable pulling in vertical shafts is highly hazardous. The weight of the cable can cause it to accelerate dangerously if it slips. To mitigate risk:

• Use high-tensile steel wires or pulling grips to support the cable during installation.
• Implement fail-safe breaking mechanisms to prevent free fall in case of rupture.
• Consider pushing the cable with synchronized pushers instead of pulling, especially for long vertical runs ( ).
• Avoid closed loops of ferromagnetic steel when fixing cables to metal structures to prevent mechanical stress.

Installation Techniques

• Begin with a vertical riser and connect horizontal trays using elbows or bends to maintain smooth cable transitions ( ).
• Ensure proper snaking of the cable to accommodate thermal expansion and contraction.
• Use spring-loaded clamps or cleats to maintain constant lateral clamping force on the cable after installation ( ).
• For multiple floors, consider tee or elbow fittings to branch horizontal trays from the vertical riser ( ).

Material and Environmental Considerations

Select cable tray materials based on the environment. Aluminum and galvanized steel are common for corrosion resistance, while ladder trays allow maximum airflow and heat dissipation ( ). Ensure that tray widths and rung spacing are appropriate for the cable type and load.

Summary

Connecting cable trays in a vertical shaft requires careful design, secure support, and strict adherence to safety protocols. Proper bends, supports, and cable fixation prevent mechanical damage and ensure safe, reliable operation. Always involve qualified personnel familiar with vertical installations and local electrical codes ( ).