The field problem
Water-Treatment Plant — Hazardous Chemicals
Conventional directly attached lightning protection was proposed on containers/structures containing hazardous chemical or flammable material.
why the obvious answer can be misleading
Direct lightning-current routing on or immediately adjacent to hazardous contents can introduce heating, sparking, side-flash and electromagnetic effects. The risk must be assessed as a hazardous-facility problem, not a normal roof detail.
Why it failed
Direct lightning-current routing on or immediately adjacent to hazardous contents can introduce heating, sparking, side-flash and electromagnetic effects.
The risk must be assessed as a hazardous-facility problem, not a normal roof detail.
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
Use an engineered non-attached/interception arrangement where required, with free-standing masts/catenary concepts, calculated protection volume, separation distance, controlled down-conductor paths and coordinated bonding/earthing.
Correction & verification
Use an engineered non-attached/interception arrangement where required, with free-standing masts/catenary concepts, calculated protection volume, separation distance, controlled down-conductor paths and coordinated bonding/earthing.
Verification recorded in the case
- Verify protection geometry, separation and bonding before commissioning.
- Record as-built topology and connection points.
- Repeat the measurement or functional test under a defined condition.
- Confirm continuity and mechanical integrity of the corrected path.
- Document instrument/setup, environmental condition and test method.
- Close the NCR/case only when evidence supports the conclusion.
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.
IEC 62305-3; NFPA 780 where contractually applicable; hazardous-area requirements.
PIS reviewed field handbook · PIS-CS-018
The engineering lesson
In hazardous facilities, interception location is part of ignition-risk control.
Take the lesson into your next design review.