Copper busbar, field width (+ 40mm), suitable for busbar supports FST901N and FST903N. Width 4. Rated current (A) 1200 (985). Copper size L1 - 3 60 x 10mm. PU 1. Copper busbars. For 185mm busbar kits. Pre-assembled copper busbars in the sizes 30 x 10, 40 x 10, 50 x 10, 60 x 10mm in the following variants:. Horizontal design: - Field width. - Extended on one side (perforated copper from 20/30mm). - Extended on both sides (perforated copper from 20/30mm).