The very basic idea on how to size a copper busbar is 2 Amps/1 Sq. in (in2), these can be different in some countries. Of course this is like a “first-aid” decision, but the final decision should count on more factors. You should check the catalog of the manufacturer. They carry large currents and must be properly sized to ensure safety, performance, and. While selecting busbar one should keep in mind the application, current carrying capacity and budget as under sized busbar can cause heating and damage in bus bar while over sized busbar can affect the cost of project. Types of busbar On the basis of material, busbar is of five types: AC & DC. All our manuals recommend the DC battery cable size (and fuse size) that needs to be used for the product.