Lead-in conductors may enter a building by which method(s) when there is no continuous metallic shield that is grounded?

• A. through a rigid noncombustible nonabsorbent insulating tube or bushing
• B. through an opening provided for the purpose in which the entrance conductors are firmly secured so as to provide a clearance of at least 2 inches
• C. through a drilled window pane
• D. Any of the above

Answer: (D)

When there isn’t a continuous metallic shield that’s grounded, lead-in conductors must be protected as they enter the building. The methods shown all provide acceptable ways to achieve that protection and maintain proper clearance. Using a rigid noncombustible insulating tube or bushing gives a dedicated, protected path that keeps conductors from mechanical damage and from contacting surrounding materials. Providing an entrance opening where the conductors are firmly secured and kept with at least a 2-inch clearance ensures there’s a safe gap from edges and framing, reducing the risk of abrasion or heat transfer. Drilling through a window pane can be used as another permitted path when properly implemented and protected. Because each option offers the necessary isolation and protection without relying on a grounded metallic shield, all of the above are allowable entry methods.