What is the smallest copper wire used to ground devices or equipment?

The smallest copper wire commonly used for grounding devices or equipment is #4 copper (cu). This size is recognized by electrical standards because it provides the necessary conductivity and safety for grounding applications. Grounding wires have specific size requirements based on the National Electrical Code (NEC), which take into account factors such as the amount of current a wire can safely carry and the potential fault conditions it might encounter.

Using a smaller gauge wire, such as #6, #8, or #10, may not provide adequate safety and could lead to overheating, increased resistance, or even failure to properly ground the device, which can pose significant risks including electrical shock and fire hazards. Therefore, #4 copper wire is the minimum recommended size to ensure that grounding systems are effective and meet safety standards. This emphasis on choosing the correct wire gauge underscores the importance of adhering to electrical codes and safety practices in electrical installations.