Bus duct and plug-in feature

Claim 1

A SECTION OF LOW IMPEDANCE BUS DUCT FOR ELECTRIC POWER DISTRIBUTION, SAID SECTION COMPRISING A HOUSING HAVING OPENING MEANS IN ONE PLANAR SIDE THEREOF FOR RECEIVING A NUMBER OF BUTT TYPE CONTACT ELEMENTS OF A PLUG-IN UNIT, A MULTI-PHASE SET OF BUS BARS COMPRISING A NUMBER OF SUBSTANTIALLY FLAT BUS BARS EQUAL TO SAID NUMBER OF CONTACT ELEMENTS AND SUPPORTED WITHIN SAID HOUSING IN A PARALLEL SPACED MUTUALLY FLATWISE RELATION WITH THEIR FLAT FACES BEING DISPOSED IN PLANES SUBSTANTIALLY PARALLEL TO SAID SIDE OF SAID HOUSING, SAID BUS BARS BEING POSITIONED SUCH THAT AN IMAGINARY STRAIGHT LINE NORMAL TO SAID SIDE OF SAID HOUSING PASSES THROUGH ALL OF SAID BUS BARS, EACH OF SAID BUS BARS COMPRISING A CONDUCTING BAR AND AN INSULATING COVER SUPPORTED ON AND SUBSTANTIALLY COVERING AND CONDUCTING BAR, THE DIMENSION BETWEEN ANY TWO ADJACENT BUS BARS IN SAID SET BEING LESS THAN THE DIMENSION OF THE THICKNESS OF ANY ONE OF SAID BUS BARS, AND SAID BUS BARS BEING CONSTRUCTED AND ARRANGED SO THAT EACH CAN RECEIVE CONTACT WITH ONE OF SAID BUTT-TYPE CONTACT ELEMENTS AT AN UNINSULATED PORTION OF THE FLAT SIDE THEREOF THAT FACES SAID SIDE OF SAID HOUSING.