When a set of 120/240V overhead service conductors terminates at an approved support, what is the minimum clearance required above the roof for these conductors?

The minimum clearance requirement for overhead service conductors, such as those carrying 120/240V, is critical to ensure safety and compliance with the National Electrical Code (NEC). When these conductors terminate at an approved support and pass over a roof, they must maintain a specific vertical clearance above the roof surface to prevent accidental contact and to accommodate the potential for material build-up or other obstructions.

According to NEC Article 230, a minimum clearance of 18 inches is typically required above the roof surface where conductors pass. This clearance is designed to both protect the conductors from physical damage and reduce the risk of electrical hazards, especially due to the potential presence of people or equipment on the roof.

This requirement helps ensure that the overhead conductors are sufficiently elevated to prevent any interaction with roof traffic, ventilation systems, or potential weather-related issues such as snow accumulation. Compliance with this clearance helps maintain a safe electrical environment while allowing for maintenance and inspection of overhead service conductors.