Polarizing means for busway plug

Claim 1

A BRANCH PLUG-IN DEVICE FOR ATTACHMENT TO A BUSWAY COMPRISING A HOUSING HAVING LONGITUDINALLY EXTENDING BASE FLANGES SPACED APART TO PROVIDE AN OPEN SLOT THEREBETWEEN AND HAVING SPACED APART LONGITUDINALLY EXTENDING BUSBARS WITHIN SAID HOUSING ACCESSIBLE THOUGH SAID SLOT, ONE OF THE LONGITUDINAL EDGES OF ONE OF SAID FLANGES AND THE CORRESPONDING LONGITUDINAL EDGE OF THE OTHER OF SAID FLANGES BEING UNEQUALLY DISTANT FROM THE LONGITUDINAL CENTRAL PLANE OF SAID HOUSING, SAID PLUG-IN DEVICE COMPRISING: (A) AN INSULATING BODY PROVIDED WITH A PAIR OF TAB CONTACTS FOR ENGAGEMENT WITH A PRESELECTED PAIR OF SAID BUS BARS AND HAVING A BASE FOR MOUNTING SAID CONTACTS, (B) A POLARIZING PLATE HAVING UPTURNED OPPOSITE LATERAL FLANGES DISPOSED ON SAID BASE WITH ITS LATERAL FLANGES IN POSITION FOR ENGAGING THE OUTSIDE LONGITUDINAL EDGES OF SAID BASE FLANGES OF SAID HOUSING, (C) MEANS FOR SELECTIVELY SECURING SAID POLARIZING PLATE IN EITHER A FIRST OR A SECOND POSITION ON SAID BASE, AND (D) INDICATING MEANS IN COOPERATIVE RELATIONSHIP WITH SAID SECURING MEANS FOR PROVIDING AN INDICATION OF THE POSITION IN WHICH SAID POLARIZING PLATE IS SECURED.