Passive lightning protection systems (LPS) provide structures with the engineered conductive pathway that intercepts a lightning strike at a designed attachment point, conducts the strike current safely down the external structure surface and dissipates it into the earth — preventing the catastrophic damage that an uncontrolled lightning current would cause through internal building wiring, structural members and finishes. The term "passive" distinguishes traditional Franklin-rod and meshed-conductor protection (recognised by IEC 62305 and NFPA 780) from "active" Early Streamer Emission (ESE) products marketed under NF C 17-102. IEC 62305 and NFPA 780 do not recognise ESE air terminals — making conventional passive air termination, down conductor and earth termination the standards-compliant approach for lightning protection of buildings, telecommunications structures, fuel storage, chemical facilities and industrial installations across Europe.
A complete passive LPS comprises three external system components — air termination system (the strike-intercept network of rods, meshed conductors and catenary wires installed at the structure's highest points), down conductor system (the vertical conductive paths routing the lightning current from the air termination to the earth termination), and earth termination system (the buried electrodes that dissipate the lightning current into the surrounding soil) — plus internal protection (equipotential bonding, separation distance and surge protective devices). All components supplied by DAS Company are manufactured to IEC 62561 requirements for lightning protection system components — the international standard defining the test requirements that confirm individual product capability to handle lightning current without failure during the design lifetime of the LPS.
IEC 62305 defines four Lightning Protection Levels (LPL I–IV) corresponding to different design parameters and protection efficacies — selected based on the structure's risk assessment outcome under IEC 62305-2. LPL I (highest) applies to critical facilities, hospitals, structures storing explosive materials, irreplaceable cultural heritage and locations with very high lightning density (more than 10 flashes per km² per year) — designed with rolling sphere radius of 20m, mesh size 5×5m and down conductor spacing maximum 10m. LPL II applies to industrial facilities, commercial buildings with significant infrastructure value — rolling sphere 30m, mesh 10×10m, down conductor spacing 10m. LPL III applies to most standard residential and commercial buildings — rolling sphere 45m, mesh 15×15m, down conductor spacing 15m. LPL IV (lowest) applies to structures with limited consequence of lightning damage — rolling sphere 60m, mesh 20×20m, down conductor spacing 20m. Higher LPL classes require denser air termination coverage, more down conductors and tighter material specifications — DAS Company provides material specification matched to the designed LPL for each project.
The air termination system intercepts lightning before it strikes vulnerable building components. IEC 62305-3 recognises three accepted air termination methods: air terminals (Franklin rods), meshed conductors, and catenary wires. The rolling sphere method determines air terminal positioning — a virtual sphere of radius matching the LPL class (20m for Class I through 60m for Class IV) is rolled across the structure surface; any point that the sphere touches requires protection by an air terminal positioned higher than that contact point. The protective angle method provides a simpler design approach for smaller structures — air terminals protect a conical volume below them with the cone angle decreasing with mounting height and increasing with LPL class.
Franklin air terminal rods (tapered cylindrical rods, typically 250mm to 1500mm height above the protected surface) are the standard air termination component — installed at roof corners, ridge ends, chimney tops, parapet edges and other protruding building features that require protection. Materials cover copper (lower contact resistance, higher corrosion resistance, premium specification for premium buildings and corrosive environments), aluminium (cost-effective for most general installations, suitable where the rod connects to aluminium down conductors), stainless steel (best corrosion resistance for coastal and chemical environments) and galvanised steel (cost-effective for industrial structures with high replacement potential). Rod installation accessories — concrete bases, tripod supports, parapet clamps, hinged base supports for items projecting above roof level (such as air conditioning condensers and rooftop plant) — enable secure rod installation across the complete range of roof types and surface materials. Rod variants with hinged tripod supports are designed for wind speed up to 145 km/h, ensuring stability in exposed building locations.
Meshed conductor air termination uses a grid of horizontal conductors installed on the roof surface — providing coverage of the entire roof area with mesh size determined by the LPL class (5×5m for Class I through 20×20m for Class IV). Meshed conductor air termination is the standard approach for flat-roof commercial and industrial buildings where individual Franklin rods would not provide acceptable coverage. The mesh conductors connect through down conductors to the earth termination system, with the mesh creating an equipotential plane on the roof surface that prevents side-flashing between conductors during a strike. Conductor support brackets (concrete blocks, adhesive-base mounts, screw-fixed supports) hold the mesh conductor at the required separation from the roof surface — preventing direct conductor contact with roofing membrane that would damage the membrane during the high-temperature strike event.
Down conductors drive the lightning current from the air termination system to the earth termination system — installed vertically on the external building surface or routed through internal voids where the building structural design permits. IEC 62305-3 specifies minimum down conductor cross-section (50mm² for copper, 70mm² for aluminium, 50mm² for stainless steel and 70mm² for galvanised steel) and maximum spacing along the building perimeter (10m for Class I through 20m for Class IV). The total down conductor count depends on the building perimeter — larger buildings require multiple down conductors distributed around the perimeter to share the lightning current and reduce the current carried by any single conductor.
Down conductor material options include round copper rod and copper tape (the premium specification with lowest electrical resistance and highest corrosion resistance for long-life installations), copper-steel composite (Cu 25%) (maintains the electrical characteristics of electrolytic copper with the superior mechanical properties of steel — appropriate for installations exposed to mechanical impact), aluminium rod and aluminium tape (cost-effective for general installations, suitable where the down conductor connects to aluminium air terminals), PVC-coated copper or aluminium tape (used to blend the down conductor visually into the building facade — important for architecturally sensitive premises and listed buildings), stainless steel tape (strongly recommended in highly corrosive environments — coastal, chemical and food processing facilities), and hard-drawn copper bars (suitable for rigid connections to building structure or to test joint locations). Down conductor support clips, brackets and fixings (matched to the conductor material and the building surface — masonry, render, metal cladding, timber) provide the mechanical attachment from the conductor to the building at the specified maximum spacing (typically 1m on vertical runs, 500mm at corners and bends).
The test joint (a removable connection installed in each down conductor approximately 1m above ground level) enables periodic earth resistance measurement of the LPS without disturbing the buried earth electrode — essential for the IEC 62305 mandated annual maintenance inspection that verifies continued LPS functionality across the system service life. Modern test joints incorporate a lightning strike counter on the most direct (shortest) down conductor — recording the number of strikes the LPS has dissipated since installation, providing inspection evidence that the system has performed correctly and maintenance evidence of the actual strike loading on the installed system.
The earth termination system dissipates the lightning current into the surrounding soil — IEC 62305-3 recognises two fundamental approaches. Type A arrangement uses vertical or horizontal earth electrodes installed outside the structure to be protected, connected to each down conductor or to foundation earth electrodes without forming a closed loop. Type A arrangements require not less than two earth electrodes total — the minimum to ensure system functionality if one electrode fails. Type B arrangement uses a ring earth electrode installed in a trench at least 0.5m deep and approximately 1m from the structure foundation — providing the most reliable performance across varying soil conditions because the ring creates an equipotential plane around the structure base that reduces step and touch voltages during a strike, protecting people walking near the building during the event. Type B is the preferred approach for new construction where foundation excavation provides easy access to install the ring electrode; Type A is typical for retrofit installations on existing structures where ring excavation is impractical.
Standard earth electrode components include copper-bonded steel earth rods (1.5m, 2.4m, 3m lengths with threaded couplers for driving deeper combined lengths, the most widely installed electrode type), solid copper earth rods (premium specification for chemically aggressive soils where copper-bonded steel would corrode through to the steel core), copper earth plates (typically 600×600mm and 1000×1000mm, used in rocky soil where rod driving is impossible), copper earth tape (laid in trenches as horizontal radial electrodes or as ring earth electrodes around the structure foundation), and chemical earth electrodes (proprietary salt-filled hollow electrodes that maintain low earth resistance in high-resistivity soils where conventional electrodes would not achieve the IEC 62305 target of less than 10Ω). Earth bar and earth pit accessories — earth bars (rigid copper bars for connecting multiple down conductor terminations and equipotential bonding), earth pits (concrete or plastic chambers providing access to underground earth connections for inspection and measurement) — complete the earth termination system installation.
Beyond the external LPS components, IEC 62305-3 requires internal lightning protection through equipotential bonding — the connection of all metallic services entering the structure (water pipes, gas pipes, structural steelwork, cable trays, telecommunications cables) to a common earth bonding point. Equipotential bonding prevents side-flashing (lightning current jumping between conductive items inside the structure due to high voltage differences during a strike) that would cause fires and electrocution hazards in occupied buildings. Equipotential bonding bars (EBB) are the central connection point for all bonded items — copper bus bars with multiple drilled connection holes, installed in cable risers, plant rooms and electrical service entry points throughout the building. Bonding strips and conductors (typically 25mm² to 50mm² copper or copper-strap) provide the connection from each metallic service to the nearest EBB.
The separation distance requirement of IEC 62305-3 specifies the minimum air or insulation distance that must be maintained between the LPS components (air terminals, down conductors) and other conductive items inside the structure — calculated from the lightning current, the geometry and the routing factor. Where the separation distance cannot be physically achieved (in densely serviced buildings), bonded interconnection with SPDs at the bonding point provides an alternative solution. DAS Company supplies the EBBs, bonding conductors, mounting accessories and SPDs required for compliant internal lightning protection installation alongside the external LPS components.
IEC 62561 is the international standard series defining the test requirements for individual lightning protection system components. The series covers eight parts addressing different component types: IEC 62561-1 (connection components), IEC 62561-2 (conductors and earth electrodes), IEC 62561-3 (isolating spark gaps), IEC 62561-4 (conductor fasteners), IEC 62561-5 (earth electrode inspection housings), IEC 62561-6 (lightning strike counters), IEC 62561-7 (earthing enhancing compounds), and IEC 62561-8 (components for telecommunications systems). Each component supplied by DAS Company for LPS installation is tested and certified to the applicable IEC 62561 part — providing the documented evidence that the individual component will perform under the specified lightning current loading without failure. For LPS designers preparing the IEC 62305-2 risk assessment and the IEC 62305-3 system design, component IEC 62561 certification is the basis for confirming that the designed protection level will be achieved by the installed system.
DAS Company provides competitive B2B pricing for passive lightning protection across Europe. Product categories with available pricing include Franklin air terminal rods (copper, aluminium, stainless steel, galvanised steel variants from 250mm to 1500mm with mounting accessories), down conductor materials (copper round rod, copper tape, copper-steel composite, aluminium, stainless steel, PVC-coated variants), conductor support clips and brackets (for masonry, render, metal cladding, timber), test joints and lightning strike counters, earth electrode rods (copper-bonded steel and solid copper, 1.5m through 3m lengths with couplers), earth plates and earth tape, chemical earth electrodes, equipotential bonding bars and bonding conductors, and complete project material packages calculated from LPS design drawings. Contact our engineering team for material schedule preparation from project drawings and volume pricing for industrial, commercial and infrastructure project supply.
