Detailed Explanation of Wiring Process for Distribution Electric Cabinet

The centerline height of components on the panel and door panels must conform to specifications. Installation must consider both ease of operation and maintenance, while ensuring that electrical clearances and creepage distances meet standards, and distinguishing between primary and secondary wiring installation distances. Fasteners used for assembly must have a protective layer. Screw holes and edge burrs must be smoothed and coated with conductive paste. Appropriate tools must be used to tighten bolts, and torque must be controlled. Special attention must be paid to grounding specifications when installing cabinet power distribution components; reactors and transformers must be grounded, while circuit breakers do not.

Heating components must be installed considering heat dissipation requirements. Tubular resistors with a rated power of 75W and above must be mounted horizontally. All electrical components and accessories must be fixed to brackets or base plates and must not be suspended from electrical appliances or wiring. Each component must have a label that matches the drawings, with complete and clear markings. Component labels on the panel and door panels must be affixed to the lower or left side of the back of the component, maintaining consistent positioning. Component labels on the consumer distribution board must be affixed correctly for easy identification during later maintenance.

Protective grounding continuity is crucial for the safety of distribution cabinets. When any two metal components inside the cabinet are connected by screws, grounding washers must be used if there is an insulation layer, ensuring tooth contact. "Grasp pads" must be added at the grounding point on the door, and connecting wires should be kept as short as possible. Components susceptible to vibration damage should be fitted with rubber pads for shock absorption. Components with operating handles must be properly adjusted to prevent jamming. Pre-installed wiring bolts on busbars and components must be tightened. The grounding design of the distribution board cabinet must strictly adhere to specifications to eliminate potential grounding problems.

Rectangular copper busbars are preferred for primary circuit wiring. Insulated conductors can be used for currents ≤100A. The cross-sectional area of ​​the grounding copper busbar should be half the cross-sectional area of ​​a single phase of the incoming busbar. Busbars and branch busbars must be selected according to design requirements. The current carrying capacity of copper busbars must have a margin based on actual operating conditions. Busbars must avoid arcing areas. When three-phase busbars pass through the metal frame, they must pass through the same frame opening. Rubber washers must be added to the points where cables rub against the cabinet metal. Primary wiring in outdoor fiber distribution cabinets must be properly protected to prevent damage to the insulation layer.

Secondary circuit wiring must be constructed according to the drawings, with correct connections, secure and reliable joints, and wire harnesses arranged horizontally and vertically with clear hierarchical distinctions. The wiring method for identical components within the same contract must be consistent. Wire cross-sectional area must meet requirements: single-strand wires no less than 1.5 mm², multi-strand wires no less than 1.0 mm², current loops and protective grounding wires no less than 2.5 mm², and low-voltage loops no less than 0.5 mm². Secondary circuit wiring in the cable distribution cabinet must avoid intermediate joints. Each component connection point should have a maximum of two wires, and terminal connections should ideally not have two or more wires connected.

The electrical cabinet layout must adhere to EMC zone principles, separating power components from control components. Ensure all equipment is properly grounded. Contactors must have arc-extinguishing capabilities, and EMC filters can be installed in sensitive environments. Signal lines must enter the cabinet from one side only, with shielding layers grounded at both ends. Motor cables must be routed independently, maintaining a safe distance from control cables. Equipment generating high heat should be installed near air vents and equipped with appropriate cabinet climate control devices to prevent the effects of condensation and dust.