The NEC generally requires all metal enclosures and raceways for service conductors to be grounded, with an exception for certain metal components. What is the minimal cover distance specified for isolation?

The minimal cover distance specified for isolation is important in ensuring the safety and integrity of electrical systems. The choice of 18 inches reflects the National Electrical Code's consideration of potential hazards that could occur if metal enclosures and raceways were to become unintentionally energized.

By maintaining a distance of 18 inches, the NEC aims to provide adequate physical separation between the grounded parts and other conductive surfaces that might be accessible or in proximity to people or other equipment, thus reducing the risk of electrical shock or equipment damage.

This distance also considers installation practices and environmental factors, allowing for enough isolation in various conditions. Other distances, such as 6, 12, and 24 inches, do not align with the specific requirements set forth by the code, which focuses on the balance between safety and practical installation methods.