Lead-in conductors for transmitting stations may enter a building by which method(s) if the installation does not include a continuous metallic shield that is grounded?

Lead-in conductors for transmitting stations may enter a building by which method(s) if the installation does not include a 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, the entry of lead-in conductors into a building must be protected and secured in a way that prevents damage, moisture intrusion, and arcing. Using a rigid noncombustible, nonabsorbent insulating tube or bushing provides a dedicated, protected pathway for the conductors, keeping them away from sharp edges and building materials while offering strain relief. Providing an entrance opening specifically for the conductors with at least 2 inches of clearance from the edge helps avoid abrasion and allows a safe, sealed entry with proper securing of the conductors. Drilling through a window pane can also be a permitted method when the pane is noncombustible and the opening is properly protected and sealed. Because none of these rely on a grounded shield, each approach, installed to code with the appropriate protective hardware and sealing, is acceptable.

When there isn’t a continuous metallic shield that’s grounded, the entry of lead-in conductors into a building must be protected and secured in a way that prevents damage, moisture intrusion, and arcing. Using a rigid noncombustible, nonabsorbent insulating tube or bushing provides a dedicated, protected pathway for the conductors, keeping them away from sharp edges and building materials while offering strain relief. Providing an entrance opening specifically for the conductors with at least 2 inches of clearance from the edge helps avoid abrasion and allows a safe, sealed entry with proper securing of the conductors. Drilling through a window pane can also be a permitted method when the pane is noncombustible and the opening is properly protected and sealed. Because none of these rely on a grounded shield, each approach, installed to code with the appropriate protective hardware and sealing, is acceptable.