Air-termination positioning methods
The 2024 edition clarifies the three accepted positioning methods—Rolling Sphere, Mesh and Protective Angle—and moves detailed positioning information into Annex D. The appropriate method depends on the geometry and complexity of the structure.
Mesh is not an air-rod grid
A mesh dimension controls the conductor network. It does not mean a vertical air terminal must be installed at every mesh intersection. Additional strike receptors or masts are project-specific where protrusions, equipment or protected-volume checks require them.
Down-conductor system
Down conductors must provide suitable current paths from the air-termination system toward earth termination. Planning spacing, exposed corners, current sharing, natural components and separation-distance considerations all affect the final quantity and routing.
Earth termination and bonding
The final earth-termination arrangement may use Type A or Type B concepts depending on the project. A separate earth pit for every down conductor is not a universal IEC rule. Bonding and separation distance must be coordinated with metallic services and internal systems.
2024 edition design notes
IEC highlights clarified general/simplified separation-distance methods, updated air-termination positioning for complex structures, green-roof information, tall-building façade protrusions and closer cross-reference to the IEC 62561 component series.
Engineering Reference Table
| LPS Class | Rolling sphere radius | Mesh reference | Typical down-conductor planning spacing |
|---|---|---|---|
| I | 20 m | 5 × 5 m | 10 m |
| II | 30 m | 10 × 10 m | 10 m |
| III | 45 m | 15 × 15 m | 15 m |
| IV | 60 m | 20 × 20 m | 20 m |
Project Implementation Checklist
For an actual project, record the applicable standard edition, risk-assessment assumptions, approved drawings, selected design method, calculation revision, component specification, inspection/testing requirements and final engineering approval.
Official Source
Use the official issuing body's publication for the controlled standard text and current status.