DIN 43671

DIN 43671 rates copper busbars for continuous current. Its tables are given at a reference condition of 35 °C ambient and 65 °C busbar temperature, with correction diagrams covering ambient temperatures from 0 to 60 °C and operating temperatures up to 125 °C, together with factors for bar arrangement and the number of bars per phase. The correction factors are the part that matters in practice and the part most often skipped: a bar rated comfortably at the reference condition can be well outside its limit once enclosure temperature, bar spacing and multi-bar arrangement are applied.