1,027,707. Electric conductors. INSUL-8- CORPORATION. Sept. 25, 1964 [Oct. 14, 1963 (2)], No. 39119/64. Heading H1A. [Also in Division B7] In a system of bus-bars, each bus-bar 24 is of figure-of-8 crosssection with an electrical resistance heater wire 52 in the lobe 50 to maintain a longitudinal pick-off surface 25 free of ice, for example. An electrical insulating sheath 53 of low heat conductivity forms, with the busb ar 24, air pockets 54.