The indoor distribution box has several grounding points

An indoor distribution box typically has at least two grounding points: one on the housing and one on the mounting plate, with additional connections to the central grounding system.

Grounding Configuration

For proper grounding of an indoor distribution box:

• Primary grounding point: Attach a ground wire from one of the threaded studs at the bottom of the housing to the mounting plate .
• Secondary grounding point: Connect a second grounding wire from the mounting plate to the factory central grounding point . This ensures that all metal parts of the distribution box are effectively bonded and the total ground resistance remains below 0.1 Ohm .

Additional Considerations

• LV panels and feeders: Each LV feeder is grounded through a minimum of four ground rods, and all accessible metal parts of LV network equipment, including panels and enclosures, are bonded to the neutral conductor .
• Wire specifications: In the US, a 10 AWG (5.26 mm²) ground wire is used, while in other markets a 6 mm² wire is standard .
• System safety: Proper grounding protects personnel from electric shock, stabilizes voltage levels, and ensures reliable operation of protective devices .

Summary

In practice, an indoor distribution box has at least two dedicated grounding points—one on the housing and one on the mounting plate—plus connections to the central grounding system. For LV distribution systems, additional grounding rods and bonding to the neutral conductor are required to meet safety and regulatory standards .