For facility managers, EHS officers, and plant heads responsible for lightning-risk compliance across commercial and industrial sites in India.
Many facility managers assume their existing lightning protection report still passes muster. It often doesn’t. BIS withdrew IS 2309 in favor of IS/IEC 62305, a risk-based standard that changes how a lightning protection audit is actually performed. This guide explains what a modern lightning protection audit checks, how often you need one, and how Singh Isotech runs IEC 62305-compliant audits across India.
Why Lightning Risk Is a Serious Concern in India
It’s easy to file lightning under “acts of God” and move on, but the numbers tell a different story. India sits in one of the most lightning-active regions on the planet, and the activity isn’t holding steady, it’s climbing. The Annual Lightning Report 2024-25 recorded roughly a 400% jump in lightning strikes between 2019 and 2025.
The human cost is just as stark. Lightning kills more people in India every year than any other natural hazard, and government figures cited in the Lok Sabha put the toll at around 1,300 deaths in 2024 alone, with several independent estimates running closer to 2,000 a year once injuries and indirect deaths are factored in. Some stretches have been worse than others: parts of Bihar and Uttar Pradesh saw over a hundred deaths in just three days during April 2025.
None of that lands evenly on a factory rooftop or a hospital ward the way it lands on a farmer caught in an open field, but it should still give facility owners pause. A manufacturing plant, a warehouse full of inventory, a hospital running on uninterrupted power, a crowded mall or high-rise, these are exactly the structures where a single uncontrolled strike turns into equipment loss, downtime, or worse. The risk isn’t hypothetical. It’s measurable, it’s rising, and it’s precisely what IS/IEC 62305’s risk-based approach is built to quantify.
Why the Shift from IS 2309 to IEC 62305 Actually Matters
IS 2309:1989 treated lightning protection as a blunt exercise. Install a few air terminals, run some down conductors, ground them, done. It never asked how likely a strike was or what it would cost in lost equipment or lives.
BIS adopted IS/IEC 62305 in 2015 as the current standard for lightning protection in India, and it works very differently. It’s risk-based: you calculate the probability of a lightning event and its consequences, then assign a Lightning Protection Level (LPL) from I through IV based on that calculation.
A BIS archived copy of IS 2309 carries an explicit withdrawal notice naming IS/IEC 62305 as its replacement. Yet plenty of older installations across Indian factories and commercial buildings were never re-evaluated after the switch.
The Four Parts of IS/IEC 62305
- Part 1 – general principles of how lightning interacts with structures.
- Part 2 – risk assessment and the formulas behind your Lightning Protection Level.
- Part 3 – physical protection: air terminals, down conductors, earthing.
- Part 4 – protection of electrical and electronic systems via SPDs.
What Does a Lightning Protection Audit Actually Check?
A competent auditor walks the site with calibrated test equipment and follows a defined sequence, not a vague visual glance from the parking lot.
1. Risk-Level Calculation (IEC 62305-2)
Before touching a conductor, the auditor calculates your risk profile using building height, local ground flash density, occupancy, and the value of what’s inside. This decides which Lightning Protection Level (LPL) applies, or whether you need an LPS at all. Skipping this step is the most common shortcut in cheap audits, and the one that matters most.
2. Air Terminals and Down Conductors
Auditors check placement and condition of air terminals, conventional or ESE type, then trace every down conductor for corrosion, loose clamps, and continuity. A conductor that looks fine from the ground can still have a failed joint behind a parapet wall.
3. Earth Pit and Earthing System Testing
This is where older systems quietly fail. Earth resistance is measured using the Wenner four-point method, confirming whether your earth pits actually meet the resistance values your protection level requires, not just whether a pit physically exists.
4. Surge Protection Devices and Bonding
Internal protection under Part 4 matters as much as the rods on your roof. The audit verifies SPDs are installed at incoming power lines and checks whether they’ve quietly expired after absorbing a previous transient.
It also confirms metal pipes, ducts, and structural steel near the LPS are bonded, so current can’t side-flash to an unintended path.
Quick gut-check: does your last report mention a calculated LPL, or does it just say “system found satisfactory”? The latter is a visual inspection wearing an audit’s name tag.
A typical finding
Example: a Pune-based factory’s last report still quoted IS 2309. A current IEC 62305 audit found corroded down conductors and two failed SPDs. Fixing both brought the facility back into compliance with its required protection level and eliminated several high-priority findings., easing the testing cycle from annual to biennial. This is a generic, anonymized example used to illustrate a common pattern, not a specific client case.
Not sure where your facility stands? Schedule a free site consultation with Singh Isotech’s audit team. Call +91-9999888902 or get in touch online to book your lightning protection audit
Commercial vs. Industrial Lightning Protection Audits: What's Different
People often assume one audit format fits every building. It doesn’t. The gap between a commercial lightning protection audit and industrial lightning protection audits is wider than most realize.
Commercial Lightning Protection Audit
Office towers, malls, hospitals, and hotels usually fall into LPL III or IV. The priority is occupant safety, continuity of fire alarms and lifts, and meeting NBC and local fire NOC requirements. Audits focus on rooftop terminals, lift machine room bonding, and SPDs protecting IT and life-safety circuits.
Industrial Lightning Protection Audit
Factories and process plants are a different animal. Many fall under OISD GDN 180, which works alongside IS/IEC 62305-2 and states that any area with an explosive or hazardous atmosphere needs lightning protection regardless of the overall risk calculation. That’s a non-negotiable line, not a recommendation.
These audits also run on tighter cycles, as a rule of thumb rather than a fixed rule for every site. LPL I and II facilities should typically be audited annually, not once every two or three years. SPDs protecting equipment in explosive atmospheres typically need checks roughly every seven months.
Quick frequency rule of thumb
Higher risk, more frequent checks: LPL I-II sites annually, LPL III-IV sites every 1-2 years, explosive-atmosphere SPDs every 6-7 months.
Signs Your Facility Needs a Lightning Protection Audit Now
- Your last LPS documentation references IS 2309 instead of IS/IEC 62305.
- Nobody recalls the last earth pit resistance test.
- Visible corrosion, missing clamps, or a down conductor that vanishes behind cladding.
- New rooftop equipment (solar, chillers, antennas) added since the LPS was installed.
- Your insurer or fire department wants current compliance proof you can’t locate.
Want to check your own site first? Ask Singh Isotech for the Lightning Protection Audit Checklist (PDF) covering air terminals, down conductors, earthing, and SPDs, point by point.
How to Choose a Lightning Protection Audit Company in India
Not every firm that advertises lightning protection audit services actually runs a full IEC 62305 risk assessment. Before you sign off on a quote, here’s what separates a thorough audit partner from a box-ticking one.
Experience with IEC 62305
Ask directly: does the auditor calculate a risk level and assign an LPL, or do they just inspect what’s already installed? A provider who’s worked through IEC 62305-2’s risk formulas across multiple sectors will talk about your specific risk factors, not a generic checklist.
Calibrated Testing Equipment
Earth resistance testing, SPD diagnostics, and continuity checks all require properly calibrated instruments, not a visual once-over. Ask when their equipment was last calibrated and whether they can show calibration certificates.
Risk Assessment Capability
This is the heart of IEC 62305-2. A capable auditor should be able to explain, in plain terms, how your building’s height, occupancy, and contents fed into the LPL they assigned, and what would change that number.
PAN India Support
If you operate across multiple states, a provider with PAN India reach saves you from juggling different local contractors with inconsistent reporting standards for each site.
Detailed Reporting
A strong report includes calculated risk values, earth resistance readings, photographed deficiencies, and recommendations tied to specific IEC 62305 clauses, not a one-line “system found satisfactory.”
Knowledge of OISD Requirements
For industrial and process sites, the auditor needs working familiarity with OISD GDN 180 alongside IS/IEC 62305-2, since the two standards apply together for hazardous-atmosphere areas.
If you’re comparing quotes, ask each provider to walk you through their risk-calculation method before discussing price. The answer usually tells you everything you need to know.
How Singh Isotech Approaches a Lightning Protection Audit
Against those six criteria, here’s where Singh Isotech stands. Our lightning protection audit follows the full IEC 62305 risk-assessment methodology, not a quick visual pass. Our team calculates your actual risk level, tests earth resistance with calibrated instruments, checks every SPD, and reports exactly where you stand against the current standard.
This sits alongside our broader electrical safety audit and fire safety audit services, since lightning risk rarely exists in isolation from a building’s wider electrical picture. Our team has handled lightning protection audits and related lightning protection studies for manufacturing plants, hospitals, malls, and warehouses across Delhi NCR, Mumbai, Pune, Bengaluru, and PAN India.
Across these sectors, the same pattern shows up again and again: an LPS designed correctly on paper years ago, never re-tested against the current standard.
Frequently Asked Questions
No. BIS withdrew IS 2309:1989 in favor of IS/IEC 62305. Any report still citing IS 2309 alone is working from a retired standard.
LPL I or II facilities should be audited annually. LPL III and IV facilities can usually go every one to two years.
A lightning arrestor is just the air terminal that intercepts the strike. A complete LPS also includes down conductors, earthing, bonding, and SPDs, and an audit checks all of them.
Usually, yes. Audits typically find specific weak points, like corroded conductors or missing SPDs, that can be fixed without a full teardown.
Your calculated risk level and LPL, earth resistance readings, photographed deficiencies, and recommendations mapped to specific IEC 62305 clauses, not just a satisfactory/unsatisfactory verdict.
Increasingly, yes. Fire departments and insurers are starting to expect current lightning protection documentation as part of overall facility safety records.
Ready for a clear picture of your facility’s risk? Request your free site consultation with Singh Isotech, or call +91-9999888902. |
