A downed electrical line coming into contact with a building or person can result in electrical shock or fire. In order to protect buildings and the occupants inside them from injury or death, the National Electrical Safety Code (NESC) created clearance regulations for electrical lines that hang over or run next to buildings.
The NESC, published by the Institute of Electrical and Electronics Engineers, is considered the industry standard for electrical safety regulations. Most state regulatory commissions adopt the NESC.
The NESC publishes both vertical clearance requirements for electrical lines running over buildings and horizontal clearance regulations for electrical lines running adjacent to buildings. The vertical clearance regulation is dependent on whether or not the roof is available to pedestrians. If the roof is not accessible to pedestrians, the electrical line must be no less than 12.5 feet from the highest point of the roof. Whereas if a roof is accessible to pedestrians, the electrical lines must be no less than 13.5 feet from the highest point of the roof. The NESC considers a roof to be accessible to pedestrians if it can be casually accessed through a doorway, ramp, window, stairway, or permanently-mounted ladder by a person on foot who does not need to use extreme physical force or any special tools or devices to gain entry.