Spacings between Busbars: The spacings between busbars are critical to prevent electrical shock and ensure safe operation. ANSI switchgear standards are generally performance standards. Dielectric tests, power frequency withstand for all voltages and impulse. The Busbar Size Calculator helps engineers and electricians find the right copper or aluminum busbar dimensions based on current capacity, material type, and environmental conditions. This article explains how the calculator works, the standards it follows (IEC and NEC), and what factors influence. d air (e=0. 35), corresponding to usual indoor temperatur Vertical bar ampacity based on work by House nd Tuttle. For dc ratings of other alloys, multiply by: For 6101-T, 0.