What is NOT a recommended type of connection for lightning down conductors?

Soldering is not a recommended method for connecting lightning down conductors due to its potential to introduce weak points in the electrical connection. Unlike bolting, brazing, or welding, which create strong, durable connections that can withstand high currents and temperatures associated with lightning strikes, soldering relies on a lower melting point alloy that could easily weaken or fail under the extreme conditions present during a lightning event. This can compromise the effectiveness of the lightning protection system, making it unreliable.

In contrast, bolting creates a mechanical connection that is both strong and easily inspectable. Brazing offers a metallurgical bond that is robust and resistant to mechanical stress, while welding provides a solid and permanent electrical connection, critical for ensuring that the down conductor can safely carry the lightning strike current to the ground without any interruptions. Each of these methods supports the reliability and integrity of a lightning protection system, crucial for protecting structures from lightning damage.