Copper Busbar

Mostly corrosion, the contact resistance at bolted joints stays stable over years. Current rating in still air is unchanged. In humid or polluted environments tinning preserves the joint torque-vs-resistance relationship, which protects against long-term heating drift.

For 4000 A continuous in still indoor air, a typical sizing is 2 × 100×10 mm tinned copper bars per phase, with a temperature rise of ≤65 K above 35 °C ambient. The exact sizing depends on enclosure ventilation, bar spacing and the harmonic content. We size on request against IEC 61439 type-test data.

A compliant MTC for IS 1897 / ASTM B187 ETP busbar must show: copper purity ≥99.9 % (chemical analysis with heat/cast number), electrical conductivity ≥100 % IACS tested per IEC 60468 or ASTM B193, dimensional check (cross-section area, mass per metre), tensile strength, and an NABL-accredited lab stamp or ISO 17025 equivalent. Reject on the spot if conductivity is absent or stated only as '>98 %', there is no heat or batch number, no lab stamp, or the composition shows Sn, Pb or Zn above trace levels, those impurities directly reduce conductivity and accelerate joint corrosion. We supply fully compliant MTCs with every export batch, including the NABL lab reference number.

Standard cut-punch-bend busbars ship in 2–3 weeks. Complex assemblies (multi-bend, riser bars, off-set joints with brackets) take 3–4 weeks. We share a CAD-step file for verification before machining so there's no rework at panel build.