The requirements for grounding protection of distribution boxes are

Distribution boxes must be grounded with low-resistance connections using appropriately sized conductors to ensure safety and prevent electrical hazards. Key Grounding Requirements1.

Grounding Conductors and Connections

Each distribution box and controller must be grounded using a dedicated ground wire.

In the U

S, a 10 AWG (5. 26 mm²) wire is standard, while in other markets, a 6 mm² wire is recommended. Ground wires should connect from the threaded studs at the bottom of the housing to the mounting plate, and then from the mounting plate to the central factory grounding point.

For multiple spindles or long tool cables, additional ground wires may be required to maintain low resistance and ensure safety. 2.

Ground Resistance Limits

The total resistance between all system parts should be less than 0. 1 Ohm. When multiple grounding paths exist, the parallel resistance of tool cables and grounding wires must be calculated to ensure the total resistance remains below the safe threshold.

3.

Installation Practices

Grounding must be performed by a qualified electrician. All metal parts of the distribution box, including the electrical installation board, metal base, and appliance casings, must be reliably grounded. Protective neutral wires should be connected through the terminal board, and a leakage protector should be installed for additional safety.

4.

Environmental Considerations

Distribution boxes should be installed in dry, well-ventilated areas to prevent corrosion and overheating. In flammable or explosive environments, explosion-proof distribution boxes must be used, following specific material and grade requirements. 5.

Compliance and Testing

Grounding connections should be tested to verify resistance values meet the required limits. Proper grounding ensures the creation of an equipotential zone, reducing the risk of electric shock and protecting both personnel and equipment. By following these requirements, distribution boxes are effectively protected against electrical faults, ensuring safe operation and compliance with electrical safety standards.