The following minimum material dimension values are widely used and field-proven to conduct lightning currents to ground without excessive heating or physical damage in majority of installations. These dimensions may not fulfill national or international standards.
Table 1. Air Terminal Minimum Dimensions
| Material |
Dimension |
| Copper, aluminum |
Tube with a 16 mm (0.63 in) diameter, minimum wall thickness of 2 mm (0.08 in) |
| 8 mm (0.31 in) solid round |
| Steel |
10 mm (0.39 in) steel |
Table 2. Down Conductor Minimum Dimensions
| Material |
Dimension |
| Copper |
25 mm2 (AWG 4) solid or stranded wire or solid tape |
| Aluminum |
35 mm2 (AWG 2) in solid or stranded aluminum |
| Steel |
35 mm2 (AWG 2) solid steel or stranded wires |
Table 3. Minimum Thickness of Tapes
| Material |
Thickness |
| Copper |
1 mm (0.04 in) |
| Aluminum |
2 mm (0.08 in) |
| Galvanized steel |
2 mm (0.08 in) |
| Stainless steel |
2 mm (0.08 in) |
Table 4. Minimum Thickness of Strand Diameters in Stranded Cables
| Material |
Thickness |
| Copper |
1 mm (0.04 in) |
| Aluminum |
1.6 mm (0.06 in) |
| Steel |
1.6 mm (0.06 in) |
Table 5 and Table 6 show two examples of practical minimums for ground electrodes.
The materials are preferred because they are fairly corrosion-resistant, not because they
provide optimum conductivity.
The following table is applicable to an
arrangement of three ground rods in a triangle layout at 6-m (20-ft) spacing.
Table 5. Ground Rod Minimum Dimensions
| Material |
Thickness |
| Copper |
Solid round 15 mm (0.59 in) |
| Pipe 20 mm (0.79 in) diameter with a minimum wall thickness of 2 mm (0.08 in) |
| Copper clad solid steel |
14 mm (0.55 in) |
| Galvanized steel |
16 mm (0.63 in) |
| Galvanized steel, pipe |
25 mm (0.98 in) diameter with a minimum wall thickness of 2 mm (0.08 in) |
The following table is applicable to an
arrangement of three 10-m (33-ft) horizontal ground electrodes in Y-shape.
Table 6. Horizontal Ground Electrode Minimum Dimensions
| Material |
Thickness |
| Cu |
25 mm2 (AWG 4) solid/strand/tape with a minimum 2 mm (0.08 in)
thickness |
| Galvanized steel, round wire |
50 mm2 (AWG 1) with a minimum 8 mm (0.31 in) diameter |
| Galvanized steel, stranded |
50 mm2 (AWG 1) with a minimum strand diameter of 1.7 mm (0.07 in) |
| Galvanized steel, tape |
50 mm2 (AWG 1) with a minimum thickness of 2 mm (0.08 in) |