Materials used in external lightning protection
Materials
The following materials are preferred for use in external lightning protection systems: Hot-galvanised steel, rustproof steel (VA), copper and aluminium.
Corrosion
A risk of corrosion occurs especially when joining different material types. For this reason, no copper parts may be installed above galvanised surfaces or above aluminium parts as copper particles worn away by rain or other environmental influences can penetrate the galvanised surface. In addition, a galvanic element is created, which accelerates corrosion of the contact surface.
Examples
As you can see from the examples, the copper connection on the steel water pipe is corroded and could become detached. If two different materials that are not recommended need to be joined, bi-metal connectors can be used. The example shows the use of bi-metal connectors on a copper gutter to which an aluminium round conductor is attached. Points at increased risk of corrosion, such as insertion points into the concrete or soil, must be corrosion-protected. A suitable coating must be applied as corrosion protection to connection points in the ground. Aluminium must not be placed directly (without a distance) on, in or under plaster, mortar or concrete, or in the earth − the potential consequences of doing so are shown in our example. In the “Material combinations” table, possible metal combinations are evaluated with regard to contact corrosion in air.
