Requirements for direct burial laying of wires and cables

What are the requirements for direct burial of cables?

1. Directly buried cables should use armored cables, and the metal sheath of the armored cable should be grounded with a grounding resistance not exceeding 10 Ω.

2. When the bottom of the excavated trench is a soft soil layer, cables can be directly laid. Generally, the cable burial depth should not be less than 0.7m, and when crossing farmland, it should not be less than 1m. If there are stones or hard debris, 100mm thick soft soil or fine sand should be laid.

3. After cable laying, a 100mm thick layer of soft soil or fine sand should be laid on top, and then covered with a concrete protective plate. The coverage width should exceed 50mm on both sides of the cable.

4. Clear directional signs or stakes should be set up every 50-100m in straight sections, cable joints, bends, and when entering buildings for buried cables.

5. When cables intersect with each other, non thermal pipes and pipelines, and cross roads and walls, they must be threaded in protective pipes. The length of the protective pipe should exceed the intersection point by 1 meter, and the clear distance between intersections should not be less than 250mm. The inner diameter of the protective pipe should not be less than 1.5 times the outer diameter of the cable. It is strictly prohibited to lay cables in parallel above or below pipelines.

6. The joint positions of cables laid in parallel should be staggered with each other. The joint when the cable is laid openly should be fixed with a support plate. There should be a protective box outside the buried cable junction box to prevent mechanical damage (except for epoxy resin junction boxes).