According to OSHA, what is the minimum size for single conductors used as equipment grounding conductors?

The minimum size for single conductors used as equipment grounding conductors, according to OSHA and the National Electrical Code (NEC), is typically No. 4 AWG for copper conductors. This specification is designed to ensure that the grounding conductors can effectively conduct fault currents, helping protect both equipment and individuals from electrical shock hazards.

The reasoning lies in the requirement for adequate conductor size to ensure safety in electrical installations. A grounding conductor needs to be robust enough to carry fault current back to the source for the protective devices (like circuit breakers or fuses) to operate correctly. If the grounding conductor is too small, it may not handle these fault currents, which can result in overheating and potentially create fire hazards or failure to clear a fault in the system.

This standard is an essential aspect of electrical safety regulations that aims to protect not only electrical systems but also everyone who interacts with them. It provides clear guidelines for electrical contractors and ensures consistency across installations.