Standard Installation Specifications for Cable Trays

1. Pre‑Installation Preparation, Positioning and Layout

Height and Clearance Requirements

• Horizontal installation: Bottom elevation ≥ 2.2 m above finished floor (exceptions allowed inside distribution rooms and vertical shafts).
• Vertical installation: Protective covers are required where height is less than 1.8 m.
• Clearance to ceiling ≥ 150 mm; clearance to beam bottoms ≥ 50 mm.

Supports and Hangers

• Horizontal spacing: Normally 1.5–2.0 m; permitted up to 3.0 m for heavy‑duty loads.
• Vertical fixing: Spacing ≤ 2.0 m; the lowest bracket ≤ 300 mm above the floor.
• Alignment: Horizontal deviation ≤ 5 mm; directional deviation ≤ 10 mm on the same row.

Pipeline Avoidance

• Avoid routing above hot pipelines or below liquid pipelines.
• Parallel to thermal pipes: ≥ 0.5 m with insulation; ≥ 1.0 m without insulation.
• Crossing air ducts: Net clear distance ≥ 300 mm.

2. Assembly and Mechanical Connection

Joint Requirements

• Connecting‑plate bolts shall be fully tightened, with nuts facing outward; each end fitted with ≥ 2 anti‑loosening components.
• Joints shall not be arranged at wall or floor penetrations.

Bending Radius

• The turning radius shall comply with the minimum bending requirement of the contained cables (e.g., ≥ 10D for YJV cables).

Expansion and Deformation Joints

• Install expansion joints for steel trays over 30 m and aluminum / FRP trays over 15 m.
• Install compensated flexible connections across structural building deformation joints.

3. Multi‑Layer and Side‑by‑Side Arrangement

Vertical inter‑layer spacing

• Between power cable trays: ≥ 300 mm
• Between control cable trays: ≥ 200 mm
• Between strong‑current and weak‑current trays: ≥ 500 mm (strong current arranged above)

Same‑level arrangement

• Net spacing between adjacent parallel trays ≥ 200 mm for maintenance access.
• Cables of different voltages or applications (above / below 1 kV, power / signal) shall be separated by layers or metal partitions.

4. Grounding and Electrical Continuity (Mandatory)

• All metal trays shall achieve reliable continuous protective (PE) grounding.
• Length ≤ 30 m: at least 2 grounding points (both ends).
• Length > 30 m: add intermediate grounding points every 20–30 m.

Bonding rules

• Non‑galvanized / coated trays: bonded at each joint with ≥ 4 mm² copper flexible jumpers.
• Galvanized trays: ≥ 2 locked bolts per end permitted without separate jumpers.
• Grounding resistance: protective grounding ≤ 4 Ω; combined lightning‑protection grounding ≤ 1 Ω.

5. Fire Protection and Sealing

• All penetrations through floors, walls, and fire compartments shall be tightly sealed using certified firestop materials or fire bags.
• Fire emergency circuits shall adopt fire‑rated trays together with complete surrounding fire blocking.

6. Installation Quality and Acceptance Criteria

• Trays aligned horizontally and vertically, free from twisting or deformation; cut edges smooth and deburred.
• Brackets and hangers firmly fixed; bolts tightened with 2–3 exposed threads.
• Outdoor runs constructed with drainage slope ≥ 0.5%.
• Additional anti‑corrosion coating applied to cut and welded surfaces.