Same 1000A Busway Rating, Different Copper Sizes — Why? Understanding Design Logic Within IEC 61439-6 Compliance

We often get asked by clients and consulting engineers:

"Your 1000A busway system uses 2×(60×10 mm) copper bars, but another supplier offers 2×(50×8 mm) for the same rating. Are they cutting corners, or are you over-engineering?"

The short answer: Not necessarily. Both designs can be fully compliant with IEC 61439-6 — they simply follow different engineering design logics.