Grounding location of the distribution box

The optimal grounding point in a distribution box is the dedicated threaded studs at the bottom of the housing, connected to the mounting plate and then to the central grounding system.

Recommended Grounding Points

For effective grounding, attach a ground wire from one of the threaded studs at the bottom of the distribution box housing to the mounting plate. Then, connect a second grounding wire from the mounting plate to the factory or central grounding point. This ensures that all metallic parts of the system are at the same potential and maintains a ground resistance of less than 0.

1 Ohm, which is critical for safety and equipment protection.

Wire Sizing and Alternatives

In the US, use a 10 AWG (5. 26 mm²) ground wire; in other markets, a 6 mm² wire is recommended. For longer tool cables or multiple spindles, an additional ground wire between the mounting plate and spindle plate may be required.

For example, a 16 mm² wire (or 6 AWG in the US) ensures proper grounding regardless of cable length. If the application allows, this extra wire can sometimes be omitted, but always verify total resistance to ensure it remains below safe limits.

General Grounding Practices

Bond all metal parts of the distribution box, including enclosures, busbars, and terminal blocks, to a continuous grounding system. Use copper conductors for buried or exposed runs to prevent corrosion and maintain low resistance. Avoid double-tapping neutrals or using undersized wires, as this can compromise safety and system stability.

Test the grounding system after installation to ensure resistance is within recommended limits (typically