Ground wires in a distribution box should be connected to ensure continuity, but they are not required to be connected strictly in series; proper bonding and parallel connections are acceptable and often preferred.

Proper Grounding Practices

In a distribution box, all equipment grounding conductors (EGCs) must provide a continuous path back to the source to ensure that protective devices, such as breakers or fuses, operate correctly in the event of a fault . This does not mean that all ground wires must be connected in a single series chain. Instead, they can be grouped and bonded together using wire nuts, bus bars, or grounding terminals, as long as continuity is maintained .

Code Requirements

According to the National Electrical Code (NEC) Section 250.148, when multiple circuits enter a box, the grounding conductors must be "connected together" to maintain a reliable path, but this can be achieved with a single jumper between groups of grounds rather than connecting every wire in series . Metal boxes and devices should also be bonded to the grounding system to ensure effective fault current paths .

Practical Implementation

• Parallel or grouped connections: In multi-circuit boxes, grounds can be separated into groups and connected with a jumper wire to maintain continuity. This avoids excessive wire clutter and ensures a low-resistance path .
• Resistance considerations: The total ground resistance should be low enough to allow fault currents to trip protective devices. For example, in industrial setups, the resistance between system parts is often kept below 0.1 ohm .
• Connection to devices: Each device's grounding terminal should be connected to the box or grounding bus to ensure proper protection .

Key Takeaways

• Ground wires do not need to be connected strictly in series; parallel or grouped connections with proper bonding are acceptable.
• Continuity and low resistance are critical for safety and code compliance.
• Use appropriate wire sizes and bonding methods to ensure all devices and the box itself are effectively grounded. By following these practices, the distribution box will provide a safe and code-compliant grounding system.