When transitioning from aluminum to copper, what type of fittings must be used?

When transitioning from aluminum to copper, bi-metallic fittings are essential because they are specifically designed to provide a reliable and efficient connection between two different metals. The use of bi-metallic fittings helps to mitigate the risk of galvanic corrosion, which can occur when dissimilar metals are in contact with each other in the presence of an electrolyte, leading to deterioration of one of the metals.

Bi-metallic fittings typically consist of a small section of each metal—aluminum and copper—bonded together. This allows for mechanical and electrical continuity while combating corrosion issues. They also help maintain a strong and effective electrical connection in lightning protection systems where connectivity is crucial for safety and performance.

In contrast, using copper-only connectors would not address the necessary interface for aluminum wiring, and polymeric fittings might not provide the required electrical conductivity or resist corrosion appropriately in this specific scenario. Aluminum screws do not offer any solution for transitioning between the two metals, as they are not designed for that purpose. Therefore, bi-metallic fittings are the most suitable choice for this transition in lightning protection applications.