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When designing low-voltage distribution systems, electrical designers need to have a thorough understanding of the technical requirements related to the wiring of such systems. In this article, CHANGHUI INSTRUMENTS introduces the wiring methods and characteristics of low-voltage distribution systems, in the hope of being helpful to everyone. There are four types of wiring for low-voltage distribution systems: radial wiring, trunking wiring, \"transformer-main group\" wiring, and chain wiring. Below is a brief overview of the advantages and disadvantages of each of these four wiring methods. Changhui Instruments yunrun.com.cn/ 1. Radial wiring: An example of radial wiring is shown in Figure 1 (the diagram illustrates a three-level radial wiring configuration). Its main advantages include: ① It is relatively easy to meet the requirements for fault protection. ②Selective actions are easier to implement, and the scope of the fault interruption is small. ③It is easy to locate the faulty area, facilitating inspection and repair. Its main disadvantages are: ① Slightly poor flexibility. ②A large number of wires, cables, and conduits are required. http://yunrun.com.cn/upload/202011/15/202011150239106296.png Figure 1: Radial wiring. 2. Trunk wiring. An example of trunk wiring is shown in Figure 2. http://yunrun.com.cn/upload/202011/15/202011150240224096.png Figure 2: Trunk-type wiring. Trunk-type wiring includes the following forms: ① Enclosed busbars installed vertically in the shafts of high-rise and multi-story buildings. ②Pre-branch cables laid vertically in the shafts of multi-story buildings. ③Exposed busbars or enclosed bus ducts installed on the roof trusses of industrial buildings (or in other high locations); exposed busbars are rarely used these days. ④Plug-in enclosed busbars installed above (at a height of about 2.5 m) the small to medium power equipment arranged in rows in industrial buildings. ⑤Road lighting uses a trunking wiring system in which cables or overhead lines branch off to the luminaires. ⑥A movable trunking system in which sliding busbars are used to connect movable lighting fixtures or low-power electrical devices in a movable manner (usually, the busbars also serve as supports for mounting the fixtures). Its main advantages are: ① Good flexibility, suitable for changes, movement, or addition of electrical equipment. ②The amount of wires, cables, and conduits required is small. Its main drawback is that a fault in the main line and its branch lines (the segments between the branch points and the protective devices) results in a large area being affected by power outages. 3. “Transformer-main line group” wiring: The “transformer-main line group” is a form of the trunking type; it is used when the transformer supplies power to the entire main line or almost the entire part of it. An example of this wiring is shown in Figure 3. http://yunrun.com.cn/upload/202011/15/202011150242115036.png Figure 3: Wiring of “transformer-main trunk group”. The characteristics of this wiring method are the same as those of the trunk-type wiring, but it requires less equipment and space in low-voltage distribution cabinets. 4. Chain wiring: Chain wiring is mainly suitable for electrical devices with low reliability requirements and low power consumption (see Figure 4), socket circuits (see Figure 5), as well as lighting distribution boxes in multi-story buildings (see Figure 6). Its main advantage is saving on the use of wires, cables, and conduits ； The main drawback is that it expands the area affected by power outages in the event of a failure in the connection lines. http://yunrun.com.cn/upload/202011/15/202011150247543325.png Figure 4: Chain wiring (suitable for electrical devices with low reliability requirements and low power consumption). http://yunrun.com.cn/upload/202011/15/202011150248357801.png Figure 5: Chain wiring (suitable for applications with low reliability requirements and socket circuits). http://yunrun.com.cn/upload/202011/15/202011150249138217.png Figure 6: Chain wiring (suitable for lighting distribution boxes in multi-story buildings). The above provides a brief introduction to the four common wiring methods for low-voltage distribution systems; in electrical design, it is necessary to select and design according to the actual operating conditions.