Electrodynamic forces affecting lightning protection system components and structures

Electrodynamic (ED) forces influencing upon lightning protection (LP) components in some typical LP system configurations and conditions are studied. These include: various angles between conductors, their finite lengths, round and flat bar cross-section, grid of conductors, various heights of conductor holders, placement of conductors above metallic cladding and reinforced concrete, various materials, etc. Some practical formulas and examples (grid; conductor going from roof to wall and other) are included, and the scale of stresses affecting the components is discussed. For various current magnitudes and waveforms according to [1], ED forces are estimated by analytical formulas and numerical simulation. In typical LP components, stresses may reach a few units, tens and up to ∼180 kN/m, for maximal currents corresponding to LPL 1. For some fastening elements (screws, expansion anchors), the critical levels of current magnitudes (tens of kiloamperes), which able to pull out holders from typical base materials (wood, concrete/brick), are determined. Results are discussed and recommendations provided.