Street light power distribution is generally carried out by placing a main cable next to or inside each light pole, and then leading out an upper light line from the cable. The following is a comparative analysis of the advantages and disadvantages of the cable lead-out methods commonly used in street light power distribution.
There are two types of methods for handling street light cables to each light pole: direct placement and cut-off.
In the direct placement method, like the overhead line, the cable ends are placed all the way to the end of the line without cutting in the middle. There are three common methods for leading out power from the cable core.
(1) Breaking insulation lead-out method. A working well is added next to each light pole. The cable is broken and the lead-out line is drawn out. Regardless of whether the cable is two-core to five-core, the cable is placed in the working well. The cable sheath is broken and the cable cores are separated. The cable insulation layer of each core is removed by about 10mm. The upper light line is broken and tightly wrapped around the cable core for 4 to 5 turns. It is twisted with the own line and then led out. Wrap the broken cable insulation with waterproof insulation tape and plastic insulation tape. After the core insulation layer is broken, wrap the upper lamp wire around the core and connect the street lamp electric wire in the working well. Advantages: Save cable cost, simple construction process, no need to purchase other connectors, easy to replace cables. Disadvantages: Increase the cost of the working well. The joint is in the working well, the working well is low, easy to accumulate water, and has extremely high waterproof requirements. The cable cannot be disconnected and checked when it fails. The cable sheath cannot be sealed after being peeled off, and it cannot be effectively protected. Poor sealing of the working well increases the risk of rats biting the cable.
(2) Needle method (puncture wire clamp) The needle holder and the needle piston are pressed from high-strength plastic. After the needle piston is removed, the cable core can enter from the piston mouth, and then the piston is installed. The hand-tightening frame is manually tightened to make the brass needle pierce the cable insulation and make good contact with the cable core. The lead is fixed between 6 (hand-tightening frame) and 7 (brass nut). The contact part between the tip of the needle and the aluminum core of the cable is specially treated to prevent the battery effect between copper and aluminum. Currently, this method is widely used and can also be used on overhead cables. Advantages: Save cable costs, simple construction process, easy construction with special piercing wire clamps, and easy replacement of main cables in the working well. Disadvantages: The contact area between the piercing wire clamp needle and the wire conductor is small, which can easily cause heating at the joint. Increase the cost of the working well, the joint is in the working well, the working well is low, and it is easy to accumulate water, which requires high waterproofing. Cable faults cannot be disconnected and checked. The cable sheath cannot be sealed after peeling, and it cannot be effectively protected. The working well is not well sealed, and there is a risk of rats biting the cable. (3) On the basis of the needle method or the broken insulation lead method, the cable is filled with glue. It makes up for the lack of waterproofness of the previous two cable joint positions and the protection of the cable protective layer at the broken position. Advantages: Save cable costs, and easy replacement of main cables in the working well. Disadvantages: Increase the cost of the working well, and cable faults cannot be disconnected and checked. The glued section must be cut after the cable is disconnected, and the working well is not well sealed, and there is a risk of rats biting the cable. Cut-off type: the cable is cut off when it is led out of the control cabinet to the first light pole, and then the cable is led from the first light pole to the second light pole and so on until the last light pole. Most of the cut-off type uses the internal connection method of the light pole, and the cable enters the light pole. It is also the most commonly used lead-in method.
(1) Connect with a wire nose. After cutting the cable, remove the insulation layer and use a wire nose of the same specification (copper nose for copper core cable, copper and aluminum nose for aluminum core) to press the wire nose inserted into the cable core part with a hydraulic pliers. The method is shown in the figure. The lead-out wire should be pressed between the two flat washers. A spring washer should be added between the outer flat washer and the outer nut to maintain good contact. A transparent soft plastic tube or insulating cap with one end heat-sealed is put on the entire outside.
Advantages: The cable lead-in light pole joint is not easily soaked by water, and the cable fault is easy to disconnect. Low cost
Disadvantages: The cable is introduced into the light pole, which increases the cable cost. The cable cut produces too many joints, which increases the potential risk of joint position. There are gaps between the wires and it is not effective to waterproof
(2) Connect with a copper tube. Strip off some insulation at both ends of the cut cable, insert the core wire of equal length into the copper tube, insert the copper core of the light load into the copper tube at the middle end, and use hydraulic pliers to press the copper tube and the cable core wire together. The copper tube should be straight after pressing. Wrap the outside of the copper tube with insulating tape. Advantages: The cable introduction lamp pole joint is not easy to be soaked by water, the waterproof performance is slightly better than the cable nose, and the cost is low. Disadvantages: The cable introduction into the lamp pole increases the cable cost, the cable cutting produces too many joints, which increases the potential danger of the joint position, and the copper tube connection cannot be disconnected and can only be cut, resulting in multiple faults. The cable in the lamp pole is cut shorter and shorter.
(3) Use a special street light cable waterproof joint to connect, upgrade the original cable nose and copper tube connection, ensure the waterproof performance of the joint, and meet the disconnection performance of the cable troubleshooting. Advantages: The cable introduction lamp pole joint is not easy to be soaked by water, easy to install, good waterproof performance, easy to install and disconnect for troubleshooting without adding consumables. Disadvantages: Route the cable inside the light pole, increasing cable costs, which are slightly higher than using lugs and copper tube crimping.
There are also other, less commonly used methods, such as the twisted-on method with cut cables and the junction box method, which are not listed here.
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