Equipment grounding and distribution box connection

Equipment grounding should be connected to the distribution box via a continuous, low-resistance path using a green or bare copper conductor bonded to the panel's ground bus and all metal enclosures.

Steps to Connect Equipment Grounding

1. Identify the Grounding Conductor: Use a separate, insulated green or bare copper conductor for equipment grounding. This conductor should run continuously from the main service ground or grounding electrode system to the distribution box and all connected equipment . 2. Connect to the Ground Bus: Inside the distribution panel, locate the ground bus bar. Attach the equipment grounding conductor to this bus using a green hexagonal terminal screw, pressure connector, or approved grounding lug . Ensure the connection is secure and not easily removable. 3. Bond Metal Enclosures and Conduits: All metal conduits, raceways, and equipment enclosures entering or exiting the panel must be bonded to the ground bus. Use conduit grounding bushings and locknuts that cut through paint to ensure a reliable electrical path . For expansion or deflection fittings, install bonding jumpers to maintain continuity. 4. Connect Branch Circuits: Each branch circuit should include a grounding conductor connected to the ground bus in the panel. Wiring devices, such as outlets or switches, must have their ground terminals connected to this conductor to ensure safety . 5. Verify Continuity: Ensure the grounding system is electrically continuous from the service equipment to all downstream panels, devices, and metal enclosures. This allows fault currents to safely travel to the earth, enabling protective devices like circuit breakers to operate correctly . 6. Compliance with NEC: Follow NEC Sections 250.30, 250.50, 250.130, and 250.134 for grounding and bonding requirements. The equipment grounding conductor must not be interrupted, and connections should be made at accessible points within the service or distribution equipment .

Key Considerations

• Use UL-approved clamps and connectors for all grounding connections.
• Maintain proper conductor sizing according to NEC Table 250.122.
• Bond all communications and metal piping systems to the grounding system where required.
• Ensure that the neutral conductor is only bonded to the ground at the main service disconnect to prevent dangerous neutral currents on equipment . By following these steps, the equipment grounding will provide a safe, low-resistance path for fault currents, protecting both people and equipment from electric shock and damage.