Requirements For The Installation Of Three-phase Five-wire System In Distribution Boxes

All low-voltage power supply systems that use protective grounding in High And Low Voltage Distribution Cabinets are within the scope of application of three-phase five-wire power supply. Relevant national departments stipulate that all new construction, expansion, enterprises, commercial, residential, intelligent buildings, infrastructure construction sites and temporary lines shall adopt three-phase five-wire power supply, and the protective neutral line and working neutral line shall be laid separately. Existing enterprises should gradually change from three-phase four-wire to three-phase five-wire power supply, and the specific measures should be implemented in accordance with the requirements for three-phase five-wire laying.

The requirements for the laying of three-phase five-wire system in the distribution box are as follows: 1. When wiring with insulated wires, the protection neutral wire should be yellow-green two-color wire, and the working neutral wire should generally be black wire. When wiring vertically along the wall, the protection neutral wire should be set at the bottom, and when wiring horizontally, the protection neutral wire should be at the end close to the wall; 2. At the power transformer, the working neutral wire is led out from the neutral porcelain bushing of the transformer, and the protection neutral wire is led out from the lead-out wire of the grounding body; 3. Repeated grounding should be connected to the protection neutral wire as required, and repeated grounding on the working neutral wire is prohibited; 4. When using low-voltage cables for power supply, five-core low-voltage power cables should be used; 5. At the terminal power supply (such as gates, sockets, wall distribution Box, etc.) The working neutral line and the protective neutral line must be connected to the neutral main line respectively; 6. The transformation of old enterprises should gradually implement the method of separating the protective neutral line and the working neutral line. For example, the neutral main line is repeatedly grounded when entering the workshop. After repeated grounding, the working neutral line is laid separately, and the protective neutral line is led out from this repeated grounding body; use a four-pole leakage protection circuit breaker. The premise of circuit breaking is a three-phase four-wire system, which is changed to a three-phase five-wire system after the circuit breaker; in the overhead line power supply, the power electricity and lighting electricity are separately installed (two-shed lines), the neutral line installed with the lighting line crossbeam can be used as the working neutral line, and the neutral line installed with the power line crossbeam can be used as the protective neutral line.