Installation Specifications and Precautions for Spray‑Painted Cable Trays

The installation of spray‑painted cable trays focuses on coating protection, standardized grounding, strict spacing control, and reliable corrosion & fire protection. The complete specifications and key precautions are as follows:

1. Pre‑Installation Preparation (Core: Protect the Spray Coating)

• Material inspection: Verify tray specifications, thickness, and coating uniformity; ensure no scratches, dents, or peeling. Accessories (connecting plates, bolts, jumpers) shall be complete and compliant.
• Handling & protection: Use nylon slings for lifting; dragging and metal collision are strictly prohibited. Place soft pads under stacking areas and prevent welding slag spatter. After cutting, deburr and repair with spray paint or zinc‑rich paint immediately.
• Support/hanger setting: Horizontal spacing ≤ 1.5 m (≤ 1.2 m if width ≥ 400 mm); vertical spacing ≤ 2 m. Install supports 300–600 mm at bends and branches. Add anti-sway brackets within 0.5 m on both sides of deformation joints.

2. Tray Installation Specifications (Core: Straightness, Firmness, Anti‑Damage)

• Horizontal & vertical alignment: Horizontal deviation ≤ 2 mm/m; vertical deviation ≤ 1.5 mm/m. Nuts shall be installed uniformly on the outer side to keep the inner surface smooth and avoid cable abrasion.
• Connection requirements: Use special connecting plates and M8 bolts; each end shall have ≥ 2 bolts with lock washers. Straight‑section joint gap ≤ 0.5 mm. Install expansion joints every 25 m (joint width 20 mm).
• Multi‑layer & pipe crossing: Reserve operating space ≥ 300 mm between layers. Install above water pipes and below heat pipes. Maintain clearances parallel to or crossing with pipelines in accordance with standards.
• Lifting safety: Manual lifting for sections ≤ 3 m; two‑point lifting for sections > 3 m (lifting points at 0.2L from each end). Secure immediately after positioning to prevent sliding.

3. Electrical Grounding (Core: Bonding & Continuity – Mandatory)

• Jumper requirements: Spray‑painted cable trays must be grounded by bonding using copper braided wire ≥ 4 mm² or BV yellow‑green wire. Remove coating at grounding holes and use serrated washers for reliable contact.
• Overall grounding: Connect to PE main line at ≥ 2 points along the entire length; add connections every 20–30 m if total length exceeds 30 m. Both start and end points must be grounded. Section resistance ≤ 0.00033 Ω; total length resistance ≤ 0.5 Ω.
• Bonding locations: Both ends of connecting plates, bends, branches, reducers, and expansion joints.

4. Cable Laying and Filling Ratio

• Filling ratio: Power cables ≤ 40%; control cables ≤ 50%; reduce by an additional 10% at bends.
• Separate routing: Install galvanized partitions when high/low voltage or strong/weak current cables are laid on the same tray. Cables shall be arranged neatly without crossing.
• Bending radius: ≥ 10 times the cable outer diameter to avoid insulation damage from excessive bending.

5. Key Precautions (Anti‑Corrosion, Fireproof, Anti‑Damage)

• Coating protection: Scraping and impact are strictly prohibited during installation. Repair damaged areas immediately. Use insulating spacers where dissimilar metals (e.g., galvanized supports) contact to prevent electrochemical corrosion.
• Fireproof sealing: Seal wall and floor penetrations with firestop materials to prevent chimney effect. Use fireproof trays and fireproof coatings in fire zones.
• Corrosion protection: For outdoor or humid environments, use hot‑dip galvanized + spray‑coated dual‑layer protection. Avoid long‑term immersion or exposure to strong acids/alkalis.
• Acceptance key points: Continuous grounding, firm supports/hangers, intact coating, compliant filling ratio, and tight fireproof sealing.