Can a grounded neutral wire be used as an equipment ground?

Using a grounded neutral wire as an equipment ground is not permissible under standard electrical codes and practices due to safety concerns. The neutral wire is primarily designed to carry return current and is grounded at the transformer or service panel to establish a reference point for voltage.

When a neutral wire is used as an equipment ground, there is a risk of overloading that wire with fault current, which could lead to a situation where the neutral wire does not have a low enough impedance to clear the fault effectively. This can compromise the safety of the system, creating a potentially dangerous situation where metal casings or equipment could become energized, leading to electric shock hazards.

In normal, correctly designed circuits, the equipment ground and neutral serve distinct and separate purposes to ensure the safety and reliability of electrical installations. Thus, the prohibition against using a grounded neutral as an equipment ground is a critical aspect of electrical safety codes to prevent any unintended pathways for current that can cause harm.