Indal Handbook For Aluminium Busbar Hot |link|

Busbars are rarely in open, free air. They are housed inside metal switchgear panels, and this enclosure traps heat. A general thumb rule from the INDAL design practice states that if the cross-sectional area of the busbar is , a derating factor of roughly 0.91 is applied. More restrictive enclosures would require a lower factor.

: Factors in whether the busbar is in a sheet steel enclosure or has a protective coating/sleeving. Continuous Current Ratings indal handbook for aluminium busbar hot

The layout of the busbars directly affects their cooling. For example, using provides a greater surface area for heat dissipation than a single, very thick bar. Busbars are rarely in open, free air

Instead of a single massive thick bar (e.g., 120x10mm), use multiple thinner bars (e.g., 120x5mm x 2) separated by a gap equal to their thickness. This reduces AC resistance and lowers the operating temperature by 15-20°C. More restrictive enclosures would require a lower factor