is a base preferably composed of an electrically insulating material on which the bus bar 7 is mounted the bus bar is a metal member such as copper from which the several stabs 9 extend at equally spaced intervals on one side thereof the stabs 9 are an integral part of the bus bar 7 and are so spaced as to provide for the connection of circuit breakers not shown in a conventional manner in accordance with this invention the shield 11 is a relatively thin member having a thickness of 0 007 to 0 012 inch it is comprised of a resinous material such as polyvinylchloride or polystyrene which is formed by vacuum molding the material over a die into the desired form that form comprises a sheet like base 13 and a plurality of upwardly extending projections or blisters 15 disposed to cover the several spaced stabs 9 the shield 11 is semi rigid and slightly flexible to enable yielding conformity with the overall shape of the bus bar and stabs as shown in fig3 and 4 each blister 15 comprises a flared portion or tapered walls 17 adjacent to the base 13 as well as a cup shaped portion at the apex of the tapered walls 17 and formed by opposite side walls 19 21 the side walls 19 21 and the flared portions 17 are integral with the base 13 and form small chambers into which the stabs 9 project thus.