By “Lightning rod” is a single phrase covering several quite different devices. Before you specify one, it helps to know which types of lightning rods exist, what each is actually good at, and what the standards say about them. This guide walks through the main air-termination types used on buildings and structures in India, and how to pick between them.
First: what a lightning rod is (and is not)
A lightning rod — properly, an air termination — is only the capture point of a complete lightning protection system. It does not “attract” or “prevent” lightning; it offers a controlled, low-impedance path so that if a strike happens, the current is intercepted at a chosen point and taken safely to earth. A rod without correctly sized down conductors and a low-resistance earth is not protection at all. (For what the rod itself is made of, see our guide to lightning rod materials.)
The main types of lightning rods
1. Franklin rod (simple vertical air terminal)
The original and still the most common: a solid pointed or blunt rod mounted on the highest point of a structure and bonded to down conductors. It is simple, standards-recognised and cheap. Its protected volume is calculated by the rolling sphere or protective-angle method under IS/IEC 62305, which means one rod protects a limited zone — larger roofs need several.
Best for: small buildings, houses, tanks, chimneys, individual roof plant.
2. Mesh (Faraday cage) system
Rather than one tall capture point, a grid of horizontal conductors is laid over the roof and around the perimeter, with down conductors at regular intervals. Mesh size is set by the protection level chosen (a stricter level means a tighter grid). It is unobtrusive and very robust, but it is the most material- and labour-intensive option.
Best for: large flat roofs — factories, warehouses, malls, data centres.
3. Catenary / suspended wire system
One or more horizontal conductors are strung on masts above the structure so the protected zone hangs below the wire. This suits structures you cannot or should not drill into, and open areas.
Best for: fuel and chemical storage, explosive stores, open yards, and fabric/tensile structures where nothing can be fixed to the membrane itself.
4. Mast-mounted air terminal (GI or aluminium mast)
A rod raised on a GI mast or tubular pole so the capture point sits well above roof plant, and the protected cone widens. Masts are commonly 3–9 m, guyed or base-plated, and must be bonded into the same down-conductor network. The mast is a mounting method, not a different physics — but it is often the cheapest way to bring an awkward roof inside a protected zone.
Best for: rooftops crowded with HVAC and antennae; substations; standalone equipment.
5. ESE (Early Streamer Emission) lightning arrester
An ESE terminal is designed to initiate an upward leader earlier than a passive rod, and is specified with a claimed larger radius of protection under NF C 17-102. In practice a single ESE mast can replace several Franklin rods, which is why it is popular on large sites where roof-top conductor runs are impractical. It is important to be straight about this: ESE is a contested technology. IS/IEC 62305 does not recognise the enhanced radius claim, so many Indian consultants specify ESE only where the design also stands up on conventional rolling-sphere grounds, or use it alongside a compliant system. Ask for the NF C 17-102 test report, and design the down conductors and earthing exactly as you would for a conventional system.
Best for: large campuses, stadiums, plants and open sites — where the design is verified, not assumed.
6. Natural components
Standards allow metal parts of the structure itself — profiled metal roofing, handrails, structural steel — to act as air terminations and down conductors, provided thickness and continuity requirements are met. Using them can cut cost significantly on steel-framed industrial buildings.
Comparison at a glance
| Type | Typical use | Standard basis | Relative cost |
|---|---|---|---|
| Franklin rod | Houses, small buildings, roof plant | IS/IEC 62305 | Low |
| Mesh / Faraday | Large flat roofs, industrial sheds | IS/IEC 62305 | High |
| Catenary wire | Tanks, fabric structures, open yards | IS/IEC 62305 | Medium |
| Mast-mounted | Crowded roofs, substations | IS/IEC 62305 | Low–Medium |
| ESE arrester | Campuses, plants, stadiums | NF C 17-102 (not in IEC 62305) | Medium–High |
| Natural components | Steel-framed buildings | IS/IEC 62305 | Lowest |
How to choose
- Start with a risk assessment (IEC 62305-2) — it sets the protection level, which sets mesh size, rolling-sphere radius and down-conductor spacing.
- Match the type to the roof. Flat and large → mesh. Tall and narrow → rod or mast. Nothing to fix to → catenary.
- Count the down conductors, not the rods. Most under-performing systems in the field fail on down-conductor spacing and bonding, not on the air terminal.
- Design the earth to match. A capture point is only as good as the earth it discharges into — low, stable earth resistance with proper electrodes and backfill.
- Add surge protection. The rod protects the structure; SPDs protect what is inside it.
For the full step-by-step procedure — risk class, rolling sphere, conductor sizing, earthing and SPD coordination — see our guide to lightning arrester design for buildings. For high-rise-specific issues, see lightning protection for tall buildings, and for domestic installations, lightning arrester for home.
Need help choosing? Ashlok supplies both conventional and advanced air-termination systems, with the down conductors and earthing to match — see Lightning Protection Systems, Conventional Lightning Protection and the THOR Safe Protection lightning rod.
Frequently asked questions
How many types of lightning rods are there?
In practice six: the Franklin (simple vertical) rod, mesh/Faraday systems, catenary suspended wires, mast-mounted terminals, ESE lightning arresters, and natural components of the structure. The first four and natural components are all recognised air-termination methods under IS/IEC 62305.
Is an ESE lightning arrester better than a conventional rod?
It can cover a larger area with a single mast, which reduces rooftop conductor work. But its enhanced radius of protection is claimed under NF C 17-102 and is not recognised by IS/IEC 62305, so it should be specified with evidence and with a conventional design check. Down conductors and earthing must be engineered to the same standard either way.
What is a GI mast for a lightning arrester?
A galvanised-iron tubular pole (commonly 3–9 m) that raises the air terminal above roof-top equipment so the protected zone covers the whole roof. It is a mounting arrangement — the mast itself must be bonded into the down-conductor network and earthed.
How do you protect a fabric or tensile structure from lightning?
Usually with a catenary (suspended wire) system or masts placed outside the membrane, because nothing should be fixed to or penetrate the fabric. The protected zone is then established above the structure and the down conductors run down the supporting masts to their own earth electrodes.
Does the type of rod change the earthing requirement?
No. Whatever the air termination, the system needs a low and stable earth resistance, correctly sized conductors and proper bonding. That is where most retrofits actually need work — see our guide to checking earthing resistance and Ashlok Safe Earthing Electrodes.