"Galvanised steel bolts are normally used but brass or bronze bolts have been used because their coefficients of expansion closely match the copper conductor and hence the contact pressure does not vary widely with operating temperature. Amphenol offers high-performing, low-resistance Busbar connectors with designs to conveniently distribute power between busbars, cables, and circuit boards. The design. Bus bar connectors operate by clamping, bolting, or blind-connecting onto the bus bar surface to create a low-resistance electrical path. Low contact resistance:. If there is no chance for corrosion,mild steel bolts are oK. Qualified to meet or exceed all the nationally.