No, you cannot generally wire nut four equipment grounding conductors (EGCs) to a single EGC and then connect that single EGC to the ground block or grounding busbar. Here's why, along with compliant alternatives

Why It's Not Allowed (and Dangerous):
Compromised Conductivity

A wire nut connection, while common for circuit conductors, isn't designed or tested to reliably handle the fault current that multiple EGCs might carry during a ground fault. A poor connection can introduce resistance, limiting the effectiveness of the grounding system and potentially leading to overheating and fire.

NEC Requirements

The National Electrical Code (NEC) emphasizes the importance of a low-impedance path for fault current to quickly trip the circuit breaker or GFCI. Wire nutting multiple EGCs onto one violates this principle.

Single Point of Failure

If the wire nut connection fails, all the equipment connected to those EGCs lose their ground connection, creating a severe shock hazard.

Listing Issues

Wire nuts are not listed for multiple grounding conductors.

Compliant Alternatives


Add a Grounding Busbar

This is the best solution. Install a separate grounding busbar (often a metal bar with multiple screw terminals) in the panel. Connect each EGC individually to the busbar.

Installation

The busbar must be securely bonded to the metal enclosure of the panel.2.

Pig-Tailing

If you have enough length on the EGCs, create a "pig-tail" connection. Use an approved splicing method and listed for the purpose, for example, crimp-type connector with set screws. Extend a short length of grounding conductor, splice it to the combined EGC's and land that one wire on the grounding block. The "pigtail" should be sized to handle the available fault current of the largest circuit involved.3.

Double-Lug Terminals

Some ground bars have lugs designed to accept two conductors.

Ensure the lug is specifically rated for this purpose.4. Panel Grounding Kit (If Applicable)

Some panel manufacturers offer grounding kits specifically designed to add grounding capacity to their panels. These are usually a short grounding busbar and attachment hardware.

Important Considerations



EGC Size

Ensure the EGCs are sized correctly according to the overcurrent protection device (breaker or fuse) protecting the circuit. The NEC provides tables for this (typically Table 250.122).

Continuous Run

EGCs must be continuous and unbroken from the equipment they serve back to the service equipment (main panel) grounding electrode. Splices are only permitted under specific conditions.

Metal Conduit as EGC

If the wiring is in metal conduit (rigid, intermediate, or EMT), the conduit itself can serve as the EGC, provided the connections are made using listed fittings that are suitable for grounding.*

Professional Advice

If you are unsure about any aspect of grounding, consult a qualified electrician. Incorrect grounding can be dangerous and violate electrical codes.

In summary: Never rely on wire nuts to combine multiple EGCs onto a single connection point. Use a properly sized ground busbar or other NEC-compliant method to ensure a safe and effective grounding system. Flag for review