Cable tray grounding measures must be safe and reliable. First, the material and cross-sectional area of ​​the grounding protection wire must meet the requirements, and the second setting must be correct. Cable trays, their pylons and the introduction or extraction of metal cable conduits must be protected and grounded and must comply with the following requirements:
(1) The length of the metal cable tray and its support and hanger shall be not less than 2 and connected to the grounding trunk.
(2) The minimum allowable cross-section of the copper conductor or braided copper wire at both ends of the connecting plate between the non-galvanized cable trays shall be not less than 4 mm2.
(3) There shall be no grounding jumper at both ends of the connecting plate between the galvanized cable trays, but each connecting plate shall have not less than 2 connecting fixing bolts with anti-loose nut or anti-loose washer.
The bridge grounding must meet the following requirements:
1. The grounding resistance of each cabinet and chassis is not more than 1 ohm.
2, the bridge grounding method, the application of copper plastic wire not less than 2.5mm and the main steel bar grounding.
3. The equipment room equipment adopts two independent bridge grounding methods, and the grounding of the working grounding. The working grounding resistance is not more than 4 ohms, and the combined grounding resistance is not more than 1 ohm.