The field problem
Defective Down-Conductor Installation on a Multi-Level Hotel Façade
site / existing installation
Hotel in Sharm El Sheikh with multiple façade levels and projections. The installed route included long horizontal runs, repeated direction changes, near-90-degree bends at critical edges, fixing intervals reported at approximately 5-7 m, long unsupported spans, a transition from 25 x 3 mm copper tape to 70 mm² copper cable, and a mix of bare and insulated sections.
engineering analysis
A lightning down conductor is a high-impulse-current path. Performance depends on route length, bend geometry, horizontal deviations, joint quality, mechanical fixing and electrical continuity. Long horizontal runs increase inductive effects and local potential differences; abrupt bends and poorly supported spans create electrical and mechanical weak points.
Why it failed
Engineering Analysis
A lightning down conductor is a high-impulse-current path. Performance depends on route length, bend geometry, horizontal deviations, joint quality, mechanical fixing and electrical continuity. Long horizontal runs increase inductive effects and local potential differences; abrupt bends and poorly supported spans create electrical and mechanical weak points.
Failure Scenario
Long horizontal/unsupported route -> wind movement and vibration -> stress at clamps, joints and bends -> loose/damaged connection -> higher-impedance point -> local voltage rise, sparking or side flash -> façade or nearby-service damage.
Follow the engineering
Switch between the field condition and the engineering concept. Trace the path and examine what changes.
Inspect the engineering detail
What changes
Re-study façade geometry; minimize horizontal travel; reroute around multi-level edges; smooth sharp bends; increase fixing points; eliminate long free spans; standardize conductor type where practicable; use approved transitions; coordinate the insulation philosophy; and review coastal corrosion risks.
Correction & verification
Re-study façade geometry; minimize horizontal travel; reroute around multi-level edges; smooth sharp bends; increase fixing points; eliminate long free spans; standardize conductor type where practicable; use approved transitions; coordinate the insulation philosophy; and review coastal corrosion risks.
Verification recorded in the case
- Visual route inspection; fixing-interval measurement; bend-radius verification; continuity testing; transition inspection; conductor-dimension confirmation; corrosion-compatibility review; test-joint verification; pre-closure inspection; updated as-built drawing.
References & project context
References are reproduced from the PIS casebook. Select the governing edition and project acceptance criteria before using them for a design. The diagrams explain the concept, rather than define construction dimensions.
The supplied case references IEC 62305-3:2024 and IEC 62561-2/-4/-8 editions. Exact edition and applicability must be verified against the project governing standard before publication.
PIS reviewed field handbook · PIS-CS-029
The engineering lesson
A down conductor is not successful because it eventually reaches the ground. It must reach the ground through a short, smooth, mechanically secure and electrically continuous path.
Unsupported spans, sharp bends and uncontrolled conductor transitions turn a lightning-current path into a chain of weak points.
Take the lesson into your next design review.