What ambient temperature increase should be applied for conduits exposed to direct sunlight on rooftops?

When determining the ambient temperature increase that should be applied for conduits exposed to direct sunlight on rooftops, the correct value is 60°F. This adjustment is crucial because conduits on rooftops can experience significantly higher temperatures due to direct exposure to solar radiation.

The National Electrical Code (NEC) recognizes that these conditions can lead to overheating of the conductors within conduits, potentially resulting in insulation damage or reduced lifespan. The 60°F increase is a conservative measure designed to ensure that electrical systems remain safe and operate efficiently under extreme conditions.

This adjustment accounts for both the direct heat from the sun and the various factors influencing temperature, such as the color and material of the conduit, wind exposure, and the geographic location. Adhering to this guideline helps electricians and engineers design more reliable systems that can withstand the thermal stresses experienced in rooftop environments.

Understanding and applying these temperature adjustments in your designs is essential for compliance with safety codes and ensuring the longevity of electrical installations.