According to NEC® 310.15(B)(2), what is the minimum clearance between the bottom of the conduit and the surface of a roof required to avoid adding ambient correction factors?

The minimum clearance between the bottom of the conduit and the surface of a roof required to avoid adding ambient correction factors, as specified in NEC® 310.15(B)(2), is 7/8 inch. This requirement is designed to ensure that the conduit's positioning allows air circulation around it, thus preventing the heat buildup that can occur if the conduit is placed too close to the roof surface. Excessive heat can lead to a decrease in the current-carrying capacity of the conductors inside the conduit. By maintaining this clearance, installers can minimize the potential for thermal accumulation and maintain safe and efficient operation of the electrical system. This understanding is essential for compliance with the National Electrical Code and for ensuring the longevity and reliability of electrical installations.