Installation steps for cable trays in shafts

Cable tray supports in shafts should be installed using properly spaced hangers or brackets, ensuring load capacity compliance and secure attachment to the shaft structure.

Planning and Preparation

Before installation, determine the cable tray route through the shaft, considering bends, tees, and elevation changes. Inspect the shaft for obstructions such as pipes, ducts, or structural elements, and ensure the pathway is clear. Select the appropriate cable tray type (ladder, ventilated trough, or solid-bottom) based on cable type, ventilation needs, and environmental conditions .

Support Selection

• Center-hung supports are commonly used in shafts for vertical runs, allowing cables to be deposited from either side and simplifying installation .
• Wall-mounted brackets or suspended supports can also be used depending on shaft width and structural availability .
• Ensure supports are made of steel, stainless steel, or corrosion-resistant materials suitable for the shaft environment .

Support Spacing and Load

• Standard support spacing is typically 1.5 to 2 meters (5–6.5 feet) for ladder or perforated trays, but always check the manufacturer's specifications for your tray type and load .
• Maximum load per hanger is generally 318–340 kg (700–750 lbs) for center-hung supports .
• For vertical shafts, ensure supports are aligned and level to prevent tray sagging and maintain proper cable routing.

Installation Steps

1. Mark Support Points: Use a chalk line or laser level to mark the exact locations for hangers or brackets along the shaft.
2. Install Anchors: Drill and install anchor bolts or threaded rods into the shaft walls or ceiling, ensuring secure attachment.
3. Attach Supports: Mount brackets, hangers, or center-hung supports to the anchors, verifying alignment and level.
4. Install Cable Tray Sections: Place tray sections onto the supports, using couplers or splice plates to join sections. Ensure proper spacing between rungs or tray bottoms for cable support .
5. Secure and Ground: Fasten trays to supports with bolts or clamps, and connect grounding straps as required by NEC Article 392 .
6. Check Clearances: Maintain minimum bend radii for cables and ensure trays do not interfere with other shaft utilities .

Safety and Compliance

• Always wear PPE including gloves, safety glasses, and a hard hat during installation .
• Follow NEC guidelines for cable fill ratios (typically max 50%) and grounding requirements .
• Verify that all supports can withstand mechanical loads, environmental conditions, and potential vibration within the shaft . By carefully planning the route, selecting appropriate supports, and adhering to spacing and load requirements, cable trays in shafts can be installed safely, efficiently, and in compliance with electrical codes.