1. There must be a clear grounding mark at the protective grounding point.
2. The grounding device is connected to the metal reinforcement core, metal moisture barrier layer, and armor layer in the optical cable, and the cross-sectional area of the grounding wire must not be less than 6mm2.
3. Voltage withstand level: The voltage withstand between the grounding device and the box and frame shall not be less than 3000V (DC), and there shall be no breakdown or arcing for 1 minute.
4. Insulation resistance: The insulation resistance between the grounding device and the metalworking parts of the box must not be less than 2 × 104M Ω, test voltage is DC 500V.