An aluminum down conductor should be joined using what type of connector?

When joining aluminum down conductors, using a bimetal connector is the preferred method. Bimetal connectors feature two different metal types, typically aluminum and copper, which help to ensure a secure and conductive connection while minimizing issues related to galvanic corrosion.

Aluminum conductors can undergo significant corrosion when in contact with other metals unless properly managed. Bimetal connectors provide a viable solution because they establish a mechanical bond that allows for expansion and contraction while effectively maintaining electrical continuity. This is crucial in ensuring the reliability and longevity of the lightning protection system.

In contrast, soldered connectors are not ideal because solder typically does not create a sufficiently strong mechanical connection for aluminum and can lead to joint failure. Mechanical connectors are suited for aluminum on their own, but without the inclusion of dissimilar metals, they may not address corrosion issues. Insulated connectors, while providing isolation, do not inherently address the conductivity or corrosion concerns when joining aluminum conductors. Therefore, the use of a bimetal connector is the most effective choice for joining aluminum down conductors in a lightning protection system.