Design basis
Risk assessment and LPS design under IS/IEC 62305
Lightning protection
Conventional lightning protection for roof and parapet layouts
Conventional lightning protection designed around IS/IEC 62305, with roof conductors, air terminals, bonding, down paths and earthing.
Request a specification reviewDirect answer
What should you know about conventional lightning protection for roof and parapet layouts?
Conventional lightning protection uses air terminals and a planned conductor network to intercept a strike and carry current to earth.
3E supports layouts based on IS/IEC 62305. The approved roof scheme may use 25 x 3 mm GI strip or 8 mm aluminium conductor along the parapet, with down paths, bonding and earth termination drawn together.
Roof conductor examples
25 x 3 mm GI strip or 8 mm aluminium conductor where approved
Air termination
Franklin rods, mesh or rolling-sphere arrangement as the design requires
Technical view
How is a conventional layout prepared?
Survey the real roof. Parapets, tanks, solar arrays, plant, access routes and nearby structures alter the interception and conductor layout, so a generic rectangle rarely survives contact with the building.
Why do down-conductor routes matter?
Lightning current dislikes detours. Sharp bends, long loops, hidden joints and poor bonding can spoil the planned path, which is why routes need coordination before facade and civil work close them.
Specification
What belongs in a conventional LPS schedule?
The conductor examples are documented options, not universal sizes for every structure. Risk and layout calculations remain project-specific.
- Design basis
- Risk assessment and LPS design under IS/IEC 62305
- Roof conductor examples
- 25 x 3 mm GI strip or 8 mm aluminium conductor where approved
- Air termination
- Franklin rods, mesh or rolling-sphere arrangement as the design requires
- Current path
- Down conductors, test joints, bends, bonding and earth termination
- Coordination
- Equipotential bonding and surge protection addressed alongside the external system
- Enquiry inputs
- Roof plan, levels, use, incoming services, equipment and existing earthing
Applications
Where is conventional lightning protection used?
Use the application to settle the duty, material, dimensions and evidence required in the offer.
- 01
Industrial buildings
Roof networks shaped around plant, services, access and the assessed protection level.
- 02
Solar facilities
Air termination and conductor routes coordinated with arrays, inverter areas and earth networks.
- 03
Commercial and institutional buildings
Parapet and roof layouts integrated with bonding and surge coordination.
Questions from site and procurement teams
What should be clear before you proceed?
Is one Franklin rod enough for a building?
Not by assumption. Air-terminal count and position follow the risk assessment, roof geometry and selected design method.
Can 8 mm aluminium replace 25 x 3 mm GI everywhere?
No. Both are documented roof-conductor options, but the approved design, joints, exposure and metal interfaces control the final choice.
Does conventional LPS need separate earthing?
The earth arrangement follows the complete design. It must be coordinated with bonding, spacing, test points and the site's existing earth network.
Bring us the drawing
Have a roof plan for review?
Send roof levels, exposed equipment, building use, conductor preference and existing earthing. We will begin with the risk and route, not a rod count.
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