Make sure to use galvanically compatible metals in lightning protection system components and surface materials on which the components are mounted. For example, do not connect copper to aluminum. For more information, see Table 1.
CAUTION Do not use together metals that are not galvanically compatible. Bad matching accelerates their corrosion in the presence of moisture. |
With aluminum conductors, use only connection devices designed for aluminum. Make sure to use the right fastening torque.
Examples of metals to use with copper
- Nickel
- Brass
- Tin
- Lead
- Stainless steel
- Monel (nickel–copper alloy)
Examples of metals to use with aluminum
- Magnesium
- Zinc
- Galvanized steel
- Stainless steel
- Lead
- Wrought iron
- Galvalume (an aluminum-coated sheet steel product)
Table 1 lists generic guidance on materials and their use in different environments and conditions. Consider the conditions and requirements of individual sites when deciding on materials and their use.
Material | Use | Corrosion | ||||
---|---|---|---|---|---|---|
In Open Air | In Earth | In Concrete | Resistance | Increased by | May be destroyed by Galvanic Coupling with | |
Copper | Solid | Solid | Solid | Good in many environments | Sulphur compounds | – |
Stranded | Stranded | Stranded | – | Organic materials | – | |
– | As coating | As coating | – | – | – | |
Hot galvanized steel123 | Solid | Solid | Solid | Acceptable in air, in concrete, and in benign soil | High chlorides content | Copper |
Stranded 4 | – | Stranded 4 | – | – | – | |
Steel with electro-deposited copper | Solid | Solid | Solid | Good in many environments | Sulphur compounds | – |
Stainless steel | Solid | Solid | Solid | Good in many environments | High chlorides content | |
Stranded | Stranded | Stranded | – | – | – | |
Aluminum | Solid | Unsuitable | Unsuitable | Good in atmospheres containing low concentration of sulphur and chloride | Alkaline solutions | Copper |
Stranded | – | – | – | – | – | |
Lead 5 | Solid | Solid | Unsuitable | Good in atmospheres with high concentration of sulphates | Acid soils | Copper |
As coating | As coating | – | – | – | Stainless steel |
1 Galvanized steel may be corroded in
clay soil or moist soil.
2 Galvanized steel
in concrete should not extend into the soil due to possible corrosion of the steel
just outside the concrete.
3 Galvanized steel
in contact with reinforcement steel in concrete should not be used in coastal areas
where there may be salt in the ground water.
4 Stranded
conductors are more vulnerable to corrosion than solid conductors. Stranded
conductors are also vulnerable where they enter or exit earth/concrete positions.
This is the reason why stranded galvanized steel is not recommended in
earth.
5 Use of lead in the earth is often banned or restricted due to environmental
concerns.