What method is recommended for ensuring that bonding fittings in lightning protection systems are secured?

The recommended method for ensuring that bonding fittings in lightning protection systems are secured is compression under bolt or screw heads. This method is effective because it provides a reliable mechanical connection that can withstand the forces generated during a lightning event. The compression created by tightening bolts or screws ensures a strong electrical bond, which is crucial for the effective operation of the lightning protection system.

Using compression also allows for easy inspection and maintenance of the fittings, which is essential for ensuring ongoing reliability and safety in the system. This method aligns with the standards established in lightning protection practices, emphasizing the importance of secure and conductive connections in the overall performance of the system.

The other methods mentioned may not provide the same level of reliability or electrical continuity. For instance, welding can create a strong bond, but it may not be as easily assessable for maintenance and inspection. Adhesive compounds might not withstand the environmental conditions and mechanical stresses that lightning protection systems face, and wrapping with insulating tape does not offer a proper electrical connection, which is critical in this context.