Guide · Lightning protection
Lightning Arrester Guide for Kerala Homes and Buildings
Quick answer: a lightning arrester is a metal terminal fixed at the highest point of a building and connected, through a copper down conductor, to an earth electrode. It intercepts a lightning strike and carries the current safely into the ground. In Kerala, IS 2309 and IS/IEC 62305 govern how it is designed, installed and earthed.
This guide covers what a lightning arrester is, how it works, the two types you will be offered, ELSAFE’s packages, and what Indian standard IS 2309 requires for a house, flat, school or factory in Kerala.
At a glance
What is a lightning arrester?
A lightning arrester is the part of a lightning protection system that gives a strike a deliberate, low-resistance path to the ground so the current bypasses the building and everything inside it. It does not stop lightning; it decides where the lightning goes. The term is used for two different devices, and a complete system uses both.
The rooftop arrester (air terminal)
A rod or ESE head on a mast at the highest point of the building. It intercepts the direct strike. This is what Kerala homeowners mean by “lightning arrester for a house”.
The panel-side arrester (surge arrester / SPD)
A small device inside the distribution board that clamps the voltage surge a strike induces in the wiring. It protects the inverter, TV and computers; it does nothing against a direct hit.
How does a lightning arrester work?
Every arrester works on one principle: very high resistance in normal conditions, very low resistance the instant a surge appears. The terminal intercepts the strike, the down conductor carries the current down the outside wall, the earth electrode disperses it into the ground, and the arrester returns to its idle state ready for the next strike.
Interception
The terminal, the highest conductive point, launches an upward streamer that meets the descending leader, so the strike attaches to it instead of the roof.
Conduction
A down conductor, typically a 50SQmm OR 20 × 3 mm copper or GI strip, carries the current down the outside wall by the shortest straight route.
Dispersion
An earthrod or electrode dumps the current into the ground. IS 2309 requires the whole system to measure 10 ohms or less.
Recovery
The arrester returns to its high-resistance state, ready for the next strike. A well-made unit survives many strikes.
The design pulse in IEC 62305 is 10/350 microseconds with peaks up to 200 kA. Getting that to earth without a side-flash into pipes, rebar or wiring is why bonding and earthing matter as much as the rod itself.
Lightning arrester types: conventional vs ESE
You will be offered two kinds of air terminal. A conventional Franklin rod is a passive copper rod that protects a cone or rolling-sphere zone beneath it and is fully covered by IS/IEC 62305. An ESE head claims to launch its streamer earlier and so cover a wider radius; it is certified to NF C 17-102 but that extra radius is not recognised by IEC 62305.
| Feature | Conventional (Franklin rod) | ESE (early streamer emission) |
|---|---|---|
| What it is | Pointed copper or copper-bonded rod, 1–2 m, on a mast | Head with a triggering device that launches its upward streamer earlier |
| Stated coverage | Cone below the rod (IS 2309 uses 45°) or the rolling-sphere zone | 20 to 60 m radius depending on model and mast height |
| Standards | IS/IEC 62305 and IS 2309 | NF C 17-102 (France), UNE 21186 (Spain); not recognised by IEC 62305 |
| Best for | Houses, small buildings, anywhere several rods can be placed | Large roofs, campuses, open sites where one unit replaces many rods |
| ELSAFE models | Copper Franklin rod, Teksai TEK1000 spherical gap | LSG PROTECT ThunderGuard ELITE, Alltec TerraStreamer |
The honest caveat. IEC 62305-3 sizes an ESE head as a plain rod of the same height, and a 2000 review by the US National Institute of Standards and Technology called the scientific basis for ESE claims “far from certain”. ESE is legal and widely used in India and suits large open sites. Our advice: insist on the NF C 17-102 test certificate, and for a critical building treat the ESE radius as a margin, not the design basis.
How much area does a lightning arrester cover?
Coverage depends on the terminal’s height and the protection level you design to. IEC 62305 defines four levels with rolling-sphere radii of 20, 30, 45 and 60 m; a 0.5 m rod at level IV protects about 15 m between rods. ESE makers quote 20 to 60 m radii, but any radius quoted without mast height, level and tested advance time is marketing, not engineering.
For a rod of height h under sphere radius r, the maximum spacing between rods is d = 2√(2rh − h²). We run this check for every roof we survey and show you the drawing before quoting.
ELSAFE lightning arrester packages and prices
All packages include a fibre-reinforced non-conductive mast with GI mast and base, earthing to the NF C 17-102 standard and a 15-year replacement warranty on the arrester.
| Package | Arrester and stated radius* | Down conductor | Earthing | Surge arrester | Extras | Price |
|---|---|---|---|---|---|---|
| Teksai Premium | Teksai TEK1000 spherical gap, 20 m | 25 m of 50 mm² copper cable, HDPE clamps | 2 × 2 m copper-bonded rods with Teksai graphite compound | LSG 50 kA, Class 1+2, three-phase | — | ₹73,350 |
| Teksai Ultimate | Teksai TEK1000 spherical gap, 20 m | 25 m of 50 mm² copper cable, HDPE clamps | 2 × 2 m copper-bonded rods with Teksai graphite compound | LSG 100 kA, Class 1+2, three-phase | Strike counter | ₹93,350 |
| LSG ESE | LSG PROTECT ThunderGuard ELITE ESE, 60 m | 25 m of 50 mm² copper cable, stainless clamps | 2 × 2 m copper-bonded rods with Teksai graphite compound | LSG 50 kA, Class 1+2, three-phase | — | ₹91,750 |
| LSG France Ultimate | LSG PROTECT ThunderGuard ELITE ESE, 60 m | 25 m of 50 mm² copper cable, stainless clamps | 2 × 2 m copper-bonded rods with Teksai graphite compound | LSG 100 kA, Class 1+2, three-phase | Strike counter, EQB50 equipotential bonding | ₹1,05,750 |
| ALLTEC USA ESE | Alltec TSP20 ESE, 60 m | 25 m of 50 mm² copper cable, HDPE clamps | 2 × 2 m copper-bonded rods with Teksai graphite compound | LSG 100 kA, Class 1+2, three-phase | Strike counter | ₹1,25,750 |
| ALLTEC USA Ultimate | Alltec TSP20 ESE, 60 m | 25 m of 70 mm² copper cable, stainless clamps | 2 × 2 m copper-bonded rods with Teksai graphite compound | LSG 100 kA, Class 1+2, three-phase | Strike counter, EQB50 bonding, exothermic earthing bonds | ₹1,56,250 |
Prices as listed on keralalightningprotection.com during a limited-period offer; installation and GST as quoted. *Manufacturer’s stated radius; actual coverage depends on mast height, protection level and site conditions. See the full package comparison on our Kerala service page.
Lightning arrester for a building: what IS 2309 requires
India’s code of practice, IS 2309:1989, has largely been superseded by IS/IEC 62305, but it is still what most installers and inspectors work to, and its rules are easy to check on site: terminal at the highest point, copper strip or rod conductors, one down conductor per 30 m of perimeter, the whole system earthed to 10 ohms or less, and a test joint on every conductor.
| Requirement | IS 2309 rule | What it means on a Kerala site |
|---|---|---|
| Terminal position | Highest point; no part of the roof more than 9 m from a conductor | Corners first, then mid-points on long roofs |
| Conductor size | 20 × 3 mm copper, aluminium or GI strip, or 8 mm rod | Copper or copper-bonded near the coast; bimetallic connectors where aluminium meets copper |
| Down conductors | One per 30 m of perimeter; no more than 10 m apart on buildings over 20 m tall | Outside the walls, shortest straight path, bends of 20 cm radius or more |
| Earth resistance | Whole system 10 Ω or less | On laterite or rock the code allows a ring conductor or drilled, backfilled electrodes; we use chemical earthing compound |
| Test joint and records | A test joint on every down conductor; inspection and earth test at intervals not exceeding 12 months; log book | We measure the resistance in front of you and hand over the reading |
| Bonding and surge protection | Bond all roof metal to the system | Plus SPDs on the incoming line and, for solar, at the inverter |
Two Kerala points: coastal air is salt-laden, so use bimetallic connectors wherever aluminium meets copper; and earth resistance rises sharply in the dry months, which is why we put a chemical earthing electrode with backfill compound under every arrester we install.
Why this matters in Kerala
The highest strike frequency is in Kottayam and the midland-foothill belt, with Pathanamthitta, Idukki, Ernakulam and Thiruvananthapuram also named in CUSAT research reported by Mongabay. The Kerala State Disaster Management Authority recommends a lightning arrester on the building and surge protectors on electrical lines, alongside the IMD’s Damini warning app. See what a complete lightning protection system costs in Kerala, or find your district on our Kerala lightning protection service page.
Frequently asked questions
Which type of lightning arrester is best for a house in Kerala?
A conventional rod or a small ESE unit on a 2 to 3 m mast, one or two copper down conductors, a chemical earth pit and a Type 2 surge protector at the meter board. Larger or coastal buildings need an IS/IEC 62305 design.
How many down conductors does my building need?
Under IS 2309, at least one per 30 m of perimeter and no more than 10 m apart on buildings over 20 m tall. A small house needs one; a 60 by 20 m apartment block needs at least six.
How much does a lightning arrester cost in Kerala?
Complete residential packages run from Rs 73,350 (Teksai spherical-gap, 20 m) to Rs 1,56,250 (Alltec USA ESE, 60 m), including mast, 25 m copper conductor, two earth rods with compound, surge arrester and installation. A site survey confirms the exact figure.
Is an ESE lightning arrester approved in India?
There is no Indian standard for ESE. Units are certified to NF C 17-102 and UNE 21186 and are widely installed and accepted. IEC 62305 does not recognise the extended radius, so for critical buildings we size the system as if the ESE head were a plain rod.
How much area does one lightning arrester cover?
It depends on terminal height and the protection level. A conventional rod protects the rolling-sphere zone around it (20 to 60 m sphere radius). ESE makers state 20 to 60 m radius for their heads; we confirm the real coverage for your roof during the survey.
Sources
- IS 2309:1989, Code of practice for the protection of buildings and allied structures against lightning (Bureau of Indian Standards)
- IEC 62305-3, Protection against lightning: physical damage to structures and life hazard (IEC)
- Early Streamer Emission Lightning Protection Systems: An Overview (NIST, 2000)
- Centre for Earth Science Studies figures on Kerala lightning deaths, reported by The Wire Science
- Pre-monsoon storms intensify (Mongabay India, February 2026, CUSAT research)
- NCRB 2023 lightning death data (Down To Earth)
- Lightning warning and precautions (Kerala State Disaster Management Authority)
Get an IS/IEC 62305 design for your building
ELSAFE Protection & Control Systems, Kochi, has installed lightning protection and earthing at more than 1,000 sites across South India. ISO 9001:2008 certified, CPRI-tested arresters, 15-year replacement warranty.