How to Avoid Failing Cable Tray Grounding Inspection

1. Pre‑Work Confirmation: Control Non‑Compliance at Source

• Clarify grounding scheme
   
  All metal cable trays must be equipped with PE protective grounding; grounding shall not be omitted.
• Determine grounding points by length
   
  ≤ 30 m: Ground at both ends.
   
  ＞ 30 m: Add one grounding connection every 20–30 m.
• Prepare correct materials in advance
   
  Galvanized tray: Bolts, flat washers, spring washers, lock nuts.
   
  Spray‑painted / painted tray: Yellow‑green copper core flexible wire ≥ 4 mm².
   
  Deformation joints: Braided copper wire ≥ 16 mm².
• Clarify construction requirements
   
  Do not tighten only one bolt.
   
  Do not crimp without removing paint/coating.
   
  Do not ground only one end.

2. 8 Strict Standards During Installation

1. Full electrical continuity along the entire length.
2. All joints must be metal‑to‑metal contact (no paint, plastic or insulation blocking).
3. Galvanized cable tray connections:
    
   Each end ≥ 2 bolts; must use lock washers/nuts; nuts installed outward.
4. Spray‑painted / non‑galvanized cable tray:
    
   Each section must be bridged; paint must be removed at jumper positions before crimping.
5. Jumper wires: Yellow‑green, ≥ 4 mm², firmly fixed without looseness.
6. Sufficient grounding points:
    
   Start and end must be grounded; extra‑long sections require intermediate grounding;
    
   Boxes, cabinets and shafts must be grounded.
7. Deformation/expansion joints:
    
   Use flexible braided copper jumpers with slack to avoid tension failure.
8. Supports/hangers must be equipotential; no insulated suspension.
9. Grounding conductors must be yellow‑green; no other colors, iron or aluminum wires allowed.
10. Penetrations through walls/floors: no breaks in grounding continuity.

3. 4‑Step Post‑Installation Self‑Inspection (Guarantees Pass)

1. Check grounding points:
    
   Start, end, middle sections and incoming cabinet positions all grounded.
2. Check connections:
    
   All joints double‑bolted, locked, and properly bridged.
3. Check continuity:
    
   Use multimeter to verify continuity between any two sections;
    
   Tray and main grounding line must be continuous.
4. Check resistance:
    
   Grounding resistance ≤ 4 Ω; common grounding system ≤ 1 Ω.

4. Easy‑to‑Remember Summary