Lead-in conductors entering a building without a grounded, continuous metallic shield are allowed to enter by which methods?

• A. Any of the above
• B. through a rigid noncombustible nonabsorbent insulating tube or bushing
• C. 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
• D. through a drilled window pane

Answer: (A)

Lead-in conductors entering a building without a grounded, continuous metallic shield must be protected and secured as they pass from outside to inside. The NEC allows several compliant entry paths as long as the conductors remain protected from physical damage, moisture, and abrasion, and are properly fastened.

Using a rigid noncombustible, nonabsorbent insulating tube or bushing creates a dedicated, protective conduit that shields the conductors from damage and environmental exposure. Entering through an opening provided for the purpose and securing the conductors so there is at least a 2-inch clearance from the edges prevents chafing and ensures adequate insulation and separation from sharp edges. Entering through a drilled window pane is another permissible route because the pane can serve as a barrier while the conductors are properly secured and protected at the entry.

Because each method provides a compliant way to protect and support the conductors at entry, any of them may be used.