Earthing Strips & Wire

IS 3043 requires GI strip used as a buried earth conductor to be hot-dip galvanized to IS 4759 (minimum 610 g/m² or 85 µm coating weight). Bare mild steel strip degrades rapidly in soil and is not acceptable. Our GI strip is drawn from IS 2062 E250 base material, hot-dip galvanized, and batch-certified to IS 4759 with thickness readings at three points per coil. Copper strip and tinned copper strip are used without a coating requirement, the base material is the corrosion protection.

IS 3043 clause 5.5 and IEC 62561-1 (clamps) both cover jointing. A bolted joint using stainless or galvanized hardware with a bimetallic washer is the minimum code-compliant method for accessible joints inside chambers. For buried joints, exothermic welding (Cadweld, Thermoweld or equivalent) creates a molecular-fusion connection that does not loosen, corrode or develop contact resistance over time, it is the gold standard for buried earth grid connections and is required by many utility and petrochemical specifications. We supply both jointing methods and the exothermic moulds, positioned for the strip size and joint angle.

Direct GI-to-copper contact in damp soil or condensation-prone conditions creates a galvanic cell that destroys the zinc coating on the GI within months, accelerating the steel underneath. IS 3043 and IEC 62561-1 both require bimetallic or transition connections at every GI-to-copper interface. The correct approach is either a tinned-copper-to-GI transition lug (friction-welded or bolted with brass hardware) or a coated transition joint. We supply IEC 62561-compliant bimetallic transition lugs as part of our earthing accessories range, specifying them on the BOQ avoids the site shortcut of bolting the two metals together with a standard washer.

Flat strip has lower inductance per unit length at the high frequencies generated by lightning impulse and high-speed fault current, that makes it better for LPS down-conductors, substation earth grid loops and any run where the path inductance affects current distribution. Stranded wire is more flexible and routes through conduit or cable tray more easily, it suits equipment bonding tails (transformer body, motor frames, panel boxes). Most substation and outdoor industrial earthing uses both: flat strip for the buried grid and main down-conductors, stranded tinned copper for the equipment connection tails.