With the development of cable-based power distribution networks, when small-capacity independent loads are concentrated, cable branch boxes can be used to connect multiple branches of the cable, as branch boxes cannot directly operate on each branch.
Cable branching function: On a long line, having multiple small-area cables often leads to cable waste. Therefore, when connecting to the load, a main main cable is often used, and then, near the load, a cable branch box is used to divide the main cable into several smaller-area cables, which are then connected to the load. This wiring method is widely used in urban power grids for powering streetlights and small users.
Cable transfer function: On a long line, if the cable length cannot meet the line requirements, cable joints or cable transfer boxes must be used. For short distances, intermediate cable joints are usually used, but for longer lines, based on experience, on cable lines over 1000m, if there are multiple intermediate joints in the cable, cable branch boxes are considered for transfer to ensure safety.
Cable distribution boxes are widely used outdoors. With the advancement of technology, cable distribution boxes with switches are becoming increasingly common. Urban cables often use a dual-circuit power supply method, so some people directly refer to distribution boxes with switches as outdoor ring main units. However, most of these ring main units cannot currently achieve distribution network automation. Nevertheless, some manufacturers have launched outdoor ring main units that can achieve distribution network automation, which has blurred the lines between cable distribution boxes and ring main units.