When it is allowed to use the cable tray system to form the grounding trunk circuit, the following requirements should be met. The connection resistance between the ends of cable trays should not exceed 0.00033 ohms, and the insulating coating should be removed from the grounding holes.

1. The cable tray system should have a reliable electrical connection and be grounded (only for metal cable trays).

2. When it is allowed to use the cable tray system to form the grounding trunk circuit, the following requirements should be met. The connection resistance between the ends of cable trays should not exceed 0.00033 ohms, and the insulating coating should be removed from the grounding holes. In the 1KV and below neutral point direct grounding system, the grounding of the powered equipment is connected to the system neutral line grounding. When equipped with a dynamic cut-off power supply device, the metal cross-sectional area of the bridge frame in the step direction should not be less than the specified value.

3. When another grounding trunk line is laid along the entire length of the cable tray, at least one point of each cable tray (including the non-linear section) should be reliably connected to the grounding trunk line.

4. For vibrating places, a spring coil should be installed at the connection of the grounding part.