A steel metal cable tray serving as an equipment grounding conductor must have what minimum cross-sectional area?

The minimum cross-sectional area for a steel metal cable tray serving as an equipment grounding conductor is 0.40 square inches. This requirement is established to ensure that the cable tray can adequately handle fault currents without overheating or becoming ineffective at providing a grounding path. The cross-sectional area must be sufficient to safely conduct any fault current that might occur during a fault condition, thereby maintaining system safety and equipment protection.

The choice of 0.40 square inches is based on recognized standards in the National Electrical Code (NEC), which specifies grounding conductor sizing based on the type of equipment and its safety requirements. A larger cross-sectional area ensures lower resistance and improved conductivity for grounding purposes, which is vital for electrical safety.

Understanding this requirement is crucial for electrical contractors, as it impacts the design, installation, and maintenance of electrical systems, ensuring compliance with safety standards and guidelines.