Can the ground wires of the distribution box be connected simultaneously

Yes, all ground wires in a distribution box should be connected together to maintain a continuous protective path.

General Rule

In any junction or distribution box, all equipment grounding conductors (EGCs) must be electrically connected to ensure the continuity of the protective grounding system. This applies to both metallic and nonmetallic boxes, although metallic boxes also require a connection to the box itself via a grounding screw or clip . The connection ensures that if a device is removed or replaced, the grounding path remains uninterrupted .

Methods of Connection

• Wire Nut or Connector: Multiple ground wires can be twisted together and secured with a green-colored wire nut or other listed connector. If there are too many wires for a single connector, you can split them into groups and use a short jumper (pigtail) to connect the groups together .
• Pigtail to Device: A short conductor (pigtail) is used to connect the bundle of ground wires to the device's grounding terminal. In metallic boxes, a second pigtail connects the bundle to the box itself .
• Size Consideration: When using a jumper between groups of grounds, the conductor should match the size of the largest wire in the box or the smaller of the largest wires in each group .

Special Considerations

• Multiple Circuits: If multiple circuits enter the same box, it is not strictly required to tie all grounds together for each circuit, but it is generally recommended for safety and code compliance .
• Neutral Wires: Unlike grounds, neutral wires must be kept separate for each circuit and only connected pairwise; they are not tied together like grounds .
• Self-Grounding Devices: Some modern receptacles or switches have self-grounding features that make direct contact with a metallic box, simplifying the connection process .

Summary

Connecting all ground wires together in a distribution box ensures continuous grounding protection, complies with NEC requirements, and enhances safety. Use wire nuts, pigtails, and proper sizing to manage multiple conductors, and always bond metallic boxes to the grounding system. This approach prevents interruptions in the protective path even when devices are removed or replaced.