GI Earthing Strip (GI Earthing Flat)
Product Overview
A GI earthing strip is a flat, rectangular conductor made from mild steel and coated with a layer of zinc through hot dip galvanization. It’s used to interconnect earth electrodes, earth pits, and equipment bodies so that fault current and lightning energy have a low-resistance path into the ground. In the electrical trade, the same product is just as often called a GI earthing flat, hot dip earthing flat, or simply an earthing strip the terminology changes by region and by the engineer specifying it, but the product, the standard, and the function are identical.
Thunder Earthing supplies GI earthing strips manufactured to IS 3043, the Bureau of Indian Standards code of practice for earthing. Each strip is hot dip galvanized rather than electroplated, which is the detail that actually determines how long it lasts underground.
Hot Dip Galvanization vs Electro-Galvanization (why the coating process matters)
Not all GI earthing flats are made the same way, and this is where most buyers get caught out. There are two ways to zinc-coat a mild steel strip:
- Hot dip galvanization — the steel strip is fully immersed in a bath of molten zinc, forming a thick, metallurgically bonded coating of 85+ microns. This is what “hot dip earthing flat” specifically refers to, and it’s the process required for long-term underground earthing under IS 3043.
- Electro-galvanization (electroplating) — zinc is deposited electrically as a thin surface layer, typically 5–25 microns. It’s cheaper but far less durable — the coating can flake or delaminate under soil pressure and mechanical stress, cutting service life dramatically.
Thunder Earthing’s GI earthing strips are hot dip galvanized only — we don’t supply the electroplated variant for earthing applications, because it doesn’t hold up in real soil conditions over a project’s lifetime.
Key Features of GI Earthing Strip
- Hot dip galvanized zinc coating of 85+ microns for genuine long-term corrosion resistance
- Manufactured from mild steel strip for high mechanical strength and current-carrying capacity
- IS 3043-compliant cross-sectional area for every listed size
- Suitable as an earth conductor, earth grid interconnection, and lightning protection down conductor (under IS 2309)
- Consistent, uniform coating thickness — tested before dispatch
- Long service life: 12–20 years depending on soil resistivity and conditions
- Available as GI earthing strip / GI earthing flat in multiple standard sizes
Available Sizes of GI Earthing Flat
We supply GI earthing strips in a range of standard cross‑sections to suit residential, commercial, industrial, and substation applications. Each size is available as a hot dip galvanized GI earthing flat manufactured to IS 3043.
How to Choose the Right GI Earthing Flat Size
The right cross-sectional area depends on the prospective fault current at your installation and the earth resistivity of your soil — both of which are calculated as part of IS 3043 earthing design. As a general guide: 25×3mm and 25×6mm suit low-fault-current residential and small commercial sites, while 40×6mm and above are specified wherever a project engineer needs to safely carry higher fault currents for substations, industrial plants, and grid infrastructure. If you’re unsure which size your installation requires, our team can review your fault level and soil resistivity data and recommend the correct GI earthing strip size.
Applications of GI Earthing Strip
- Substation and grid earthing — GI earthing flat used as the main earth grid conductor connecting electrodes, transformers, and switchgear bodies
- Industrial plant earthing — interconnecting earth pits and equipment across factory floors
- Solar power plant earthing — array frame, inverter, and perimeter earthing conductor runs
- Commercial buildings and IT parks — earthing strip for server rooms, UPS systems, and DG set earthing
- Lightning protection systems — GI earthing strip used as a down conductor under IS 2309 for conventional lightning protection
- Residential earthing — smaller cross-section GI earthing flat for home and small-building earth pit connections
GI Earthing Strip vs Copper Bonded Strip vs Copper Strip
Feature | GI Earthing Strip (Hot Dip) | Copper Bonded Strip | Pure Copper Strip |
Coating/Material | 85+ micron zinc on mild steel | 250-micron copper on steel core | Solid copper |
Service life | 12–20 years | 20–30+ years | 25+ years |
Conductivity | Moderate | High | Very high |
Cost | Low | Moderate | High |
Best for | Standard/budget-conscious earthing | Long-term, corrosive-soil installations | High-conductivity, critical infrastructure |
IS 3043 compliance | Full (hot dip only) | Full | Full |
GI earthing strip remains the most widely specified conductor in India because it balances cost and compliance for the vast majority of standard earthing installations — copper bonded and pure copper options exist for projects where soil conditions or budget allow for a longer-life upgrade.
Standards & Compliance
Every GI earthing strip we supply is manufactured to IS 3043 (Code of Practice for Earthing), the standard Indian electrical inspectors and consulting engineers check against on every project.
When used as a lightning protection down conductor, the strip also meets the cross-sectional requirements of IS 2309. We supply mill test certificates confirming zinc coating thickness and steel composition on request—this is the documentation project engineers typically ask for during inspection and handover.
Why Choose Thunder Earthing
Thunder Earthing was founded in 2019 in Salem, India, by E. Vinothkumar, an electrical engineer with hands-on field experience specifying and installing earthing systems before starting the company. That field background is why we insist on hot dip galvanization only for earthing applications — we’ve seen electroplated strips fail in the ground within a few years, and we don’t supply that risk to our customers.
- Hot dip galvanized GI earthing strip only — no electroplated substitutes
- Sourced from suppliers whose coating thickness we verify batch-by-batch before dispatch
- Direct factory-gate pricing — no unnecessary middleman markup
- Bulk supply capability across India, with custom sizes available on request
- Technical support for size selection based on your fault current and soil resistivity data
Frequently Asked Questions
What is a GI earthing strip?
A GI earthing strip is a flat, hot dip galvanized mild steel conductor used to interconnect earth electrodes, earth pits, and equipment bodies in an electrical earthing system, in accordance with IS 3043.
Is GI earthing flat the same as GI earthing strip?
Yes. GI earthing flat and GI earthing strip are two names for the same product — a flat rectangular galvanized iron conductor used for earthing. The terms are used interchangeably across Indian electrical projects and supplier catalogues.
What is hot dip earthing flat, and how is it different from other GI strips?
Hot dip earthing flat refers to a GI earthing strip coated by hot dip galvanization — full immersion in molten zinc, producing an 85+ micron coating. This is different from electro-galvanized strips, which have a much thinner 5–25 micron zinc layer applied electrically and don’t last as long underground. When you’re specifying for a real installation, hot dip is the version you want.
What sizes of GI earthing strip are available?
We supply GI earthing strip / GI earthing flat in 25×3mm, 25×6mm, 32×6mm, 40×6mm, 50×6mm, 75×6mm, and 100×6mm, with custom sizes available on request.
How long does a GI earthing strip last underground?
In standard Indian soil conditions, a hot dip galvanized GI earthing strip typically lasts 12–20 years. In aggressive soils — saline coastal or acidic industrial sites — service life is shorter, and copper bonded strip is often recommended instead.