How should lead-in conductors for transmitting stations enter buildings when not protected with a metallic shield?

Lead-in conductors for transmitting stations must be properly routed when entering buildings, especially when they are not shielded by metallic protection. The option indicating that any method is acceptable reflects the flexibility in the installation of these conductors as long as some fundamental guidelines are adhered to.

When lead-in conductors enter through a wall, they can be well-sealed to prevent any potential ingress of water and foreign materials, which helps maintain the functionality of the equipment. Entering at the ceiling allows for minimal disruption within the living or working space of the building and can facilitate a neat and tidy installation while keeping the conductors high and out of the way.

Using underground routes for lead-in conductors is often preferable in terms of protecting these cables from environmental factors, reducing risks of damage from external elements, and providing better grounding opportunities. As such, all these methods—through walls, at ceilings, or underground—are deemed acceptable when the conductors are not protected by a metallic shield, making it permissible to choose any of these options based on specific circumstances and codes that might apply to different installations. Each of these entry methods serves to preserve the structural integrity and safety of the installation without compromising the system's performance.