Safety Requirements
When cables cross each other, high-voltage cables should be placed below the low-voltage cables. If one cable is protected by conduit or separated by a baffle within 1 meter of the crossing point, a distance of 0.25 meters is permissible.
When cables and thermal pipelines are adjacent or intersect, a parallel distance of 0.5m and a crossing distance of 0.25m are required if insulation measures are in place.
When cables intersect with railways or roads, they should be protected with conduits, and the protective conduit should extend 2 meters beyond the track or road surface.
4. The distance between the cable and the building foundation should ensure that the cable is buried outside the building's runoff area; when introducing the cable into the building, it should be protected with a conduit, and the protective conduit should also extend beyond the building's runoff area.
5. Cables directly buried underground should be spaced 0.25 to 0.5 meters from general grounding devices; the burial depth of cables directly buried underground should generally not be less than 0.7 meters, and should be placed below the frost layer.
Protection Measures
As the rapid development of underground power cable laying projects, higher requirements are placed on cable protection. The cable protection sleeve is made from polyethylene (PE) and steel pipes, which undergoes sandblasting and shot peening pre-treatment, dipping or coating, and heat curing processes. It is a commonly used electrical insulating tube for protecting wires and cables. Due to its excellent insulation properties, high chemical stability, resistance to rust and aging, and adaptability to harsh environments, it is widely applied.
Cable protection sleeves offer the following advantages: 1. Excellent corrosion resistance and long service life, suitable for use in humid, saline-alkali areas. 2. Flame retardant and heat-resistant, capable of withstanding long-term use at 130 degrees Celsius without deformation or combustion. 3. High strength and rigidity, allowing direct burial under roadways without the need for a concrete protective layer, thus speeding up the cable construction process. 4. Cable protection sleeves, both in terms of pipes and fittings, are flexible and can withstand external pressures and foundation settlements without damage. 5. Excellent resistance to external signal interference. 6. Smooth inner walls prevent damage to cables. The design employs a socket-and-spigot connection method for easy installation and connection. The joints are sealed with a rubber gasket, which accommodates thermal expansion and contraction and prevents the entry of dirt and sand.
Storage Method
Cables that are to be stored long-term should be considered based on their placement:
1. Under the eaves. Standard LAN cables can be used as long as they are not directly exposed to sunlight or high temperatures; it is recommended to use conduits.
2. On the exterior walls. Avoid direct sunlight exposure and human damage.
3. Inside pipes (plastic or metal). If inside pipes, be mindful of damage to plastic pipes and heat conduction in metal pipes.
4. Suspended Applications/Aerial Cables. Considering the sag and pressure of the cables, what type of bundling method will be adopted, and whether the cables will be directly exposed to sunlight.
5. Directly laying in the underground cable trench, this environment has a limited control range. Regular checks for dryness or humidity levels must be conducted on the cable trench installations.
6. Underground Pipelines. Installing auxiliary pipelines is a good method for future upgrades, cable replacements, and isolation from surface pressure and surrounding environments. However, do not expect the pipelines to remain dry, as this will affect the selection of cable types.