Lightning does not send a calendar invite before striking. It arrives unannounced, dramatic, and unforgiving. In India, lightning causes thousands of incidents every year, damaging plants, stopping production, and endangering lives. Yet, many industrial facilities believe they are “safe enough” because they installed a lightning arrester years ago.
That belief is risky.
A Lightning Risk Assessment as per IEC 62305 and NBC decides whether your plant can truly handle a lightning event. In reality, most plants fail this test. Not because lightning is unpredictable, but because compliance is often misunderstood, ignored, or treated as a checkbox exercise.
Let’s unpack the logic, the standards, and the uncomfortable truth behind widespread non-compliance.
Understanding Lightning Risk: More Than a Tall Building Problem
Many plant managers assume lightning protection only matters for tall chimneys or exposed structures. That assumption costs money and sometimes lives.
Lightning affects:
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Electrical systems
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Instrumentation and PLCs
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Data and communication lines
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Fire-prone storage areas
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Personnel working outdoors
Even a nearby strike can induce surges that destroy sensitive electronics. No direct hit required. Lightning plays dirty.
A proper lightning risk assessment evaluates direct strikes, indirect effects, and surge propagation paths. If your assessment ignores any one of these, it already violates IEC 62305.
What Is Lightning Risk Assessment as per IEC 62305?
The International Electrotechnical Commission developed IEC 62305 as a global standard for lightning protection. It is not advisory. It is systematic, mathematical, and brutally honest.
IEC 62305 consists of four parts:
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General principles
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Risk management
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Physical damage and life hazard
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Electrical and electronic systems protection
The heart of compliance lies in Part 2: Risk Management.
This section calculates risk using:
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Structure dimensions and location
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Lightning ground flash density (Ng)
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Occupancy and human presence
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Type of services entering the building
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Fire and explosion consequences
The output is not a feeling. It is a number.
If calculated risk exceeds tolerable risk, lightning protection measures become mandatory. Skipping this calculation makes the entire protection system technically invalid.
NBC Requirements in India: Where Many Go Wrong
India follows the National Building Code of India (NBC), which aligns closely with IEC 62305 for lightning protection.
NBC requires:
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Lightning risk assessment for vulnerable structures
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Design based on risk level, not guesswork
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Proper air termination, down conductors, and earthing
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Surge Protection Devices (SPDs) for incoming services
Here is the catch. NBC does not accept “installed lightning arrester” as proof of compliance. It demands engineering justification.
Many plants install systems without:
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Risk calculation reports
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Drawings linked to risk outcomes
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SPD coordination studies
On paper, they look protected. In audits, they are exposed.
Why Most Plants Are Non-Compliant (The Real Reasons)
Let’s address the elephant in the control room.
1. No Risk Calculation Was Ever Done
This is the biggest failure.
Plants often install lightning protection based on:
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Vendor recommendations
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Old drawings
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Copy-paste designs
IEC 62305 does not allow assumptions. Without a formal risk assessment, protection levels (LPL I–IV) become meaningless.
No calculation means no compliance.
2. Outdated Standards Still in Use
Some facilities still rely on IS 2309 or legacy methods without cross-checking with IEC 62305 updates.
Standards evolve. Lightning behavior data improves. Risk factors change. Using outdated references creates a silent compliance gap.
Auditors notice. Insurance companies notice faster.
3. Surge Protection Is Ignored or Misapplied
Plants love air terminals. SPDs? Not so much.
Common issues include:
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No SPDs on data and control lines
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Incorrect SPD class selection
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No coordination between Type 1, 2, and 3 SPDs
IEC 62305 treats surge protection as equal to structural protection. Ignoring it breaks the system logic.
Lightning does not stop at the roof. It travels through cables like gossip in a factory canteen.
4. Earthing Resistance Meets Numbers, Not Physics
“Earth resistance is below 2 ohms, so we are safe.”
That statement sounds confident but often hides deeper problems.
IEC 62305 focuses on:
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Earth electrode configuration
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Equipotential bonding
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Step and touch voltage control
Low resistance alone does not guarantee safety. Poor bonding can still cause dangerous voltage differences during strikes.
Nature does not read your test report.
5. Plant Modifications Without Reassessment
Plants grow. Processes change. New panels appear. Data lines multiply.
Yet, lightning risk assessments remain frozen in time.
IEC 62305 requires reassessment when:
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Building dimensions change
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Equipment density increases
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Hazardous areas expand
No reassessment means your old compliance certificate expires quietly.
Real Consequences of Non-Compliance
Non-compliance does not always announce itself with a lightning strike. Sometimes it whispers through smaller failures.
Common consequences include:
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Repeated PLC failures during storms
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Instrument drift and communication errors
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Fire incidents without clear ignition sources
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Insurance claim rejections
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Adverse findings in statutory safety audits
When lightning finally hits hard, post-incident reports often reveal what audits could have prevented.
How a Proper Lightning Risk Assessment Should Look
A compliant assessment includes:
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Site-specific lightning density data
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Structure classification and usage
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Risk calculations for loss of life, service, and economic value
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Defined Lightning Protection Level (LPL)
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Design justification linked to risk outcomes
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SPD strategy and earthing philosophy
This report should stand up to:
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Third-party safety audits
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Insurance inspections
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Regulatory scrutiny
If it cannot, it is not a risk assessment. It is a document.
Why Lightning Protection Is a System, Not a Product
Many plants treat lightning protection like buying a fire extinguisher. Install it once and forget it.
IEC 62305 treats it as a system:
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Air termination captures lightning
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Down conductors control current paths
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Earthing dissipates energy
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SPDs protect internal systems
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Bonding equalizes potentials
Remove one element, and the system weakens.
Lightning respects physics, not procurement shortcuts.
Trusted Sources and Standards Used
This article is based on:
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IEC 62305 series (Parts 1–4)
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National Building Code of India (NBC)
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CIGRÉ and IEC technical guidance on lightning protection
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Indian statutory audit practices and insurance risk frameworks
No assumptions. No filler. Only verified engineering logic.
Final Thoughts: Compliance Is Cheaper Than Recovery
Lightning risk assessment feels invisible until it saves your plant. When done correctly, nothing happens. That silence is success.
Most plants are non-compliant not because standards are complex, but because they underestimate lightning. Nature does not negotiate. It only tests.
If your plant has never undergone a formal lightning risk assessment as per IEC 62305 and NBC, you are not unlucky. You are just untested.
And lightning always tests eventually.
About the Technical Review and Authorship
Elion Technologies & Consulting Pvt. Ltd. is a professional Lightning risk assessment company in India providing NBC-compliant Lightning risk assessment and risk assessments across industrial, commercial, and institutional facilities, along with other established fire safety consultants in the country.
This blog is technically authored and peer-reviewed by certified Elion Lightning risk assessment safety professionals, ensuring compliance with applicable codes, statutory requirements, and recognised industry best practices. The content is intended to support informed decision-making and responsible management.
FAQs: Lightning Risk Assessment as per IEC 62305 & NBC
1. Is lightning risk assessment mandatory in India?
Yes. NBC mandates lightning protection for vulnerable structures, and IEC 62305 provides the accepted risk assessment methodology.
2. How often should lightning risk assessment be done?
Whenever structural changes, process expansions, or major electrical modifications occur. Periodic review is also recommended.
3. Is installing a lightning arrester enough?
No. Without risk calculation, SPD coordination, and proper earthing design, it does not meet IEC 62305 compliance.
4. Does low earth resistance ensure lightning safety?
No. Equipotential bonding and current dissipation paths matter as much as resistance values.
5. Can insurance claims fail due to non-compliance?
Yes. Insurers increasingly demand proof of compliance with IEC 62305 and NBC during claim evaluations.