Tamper proof watthour meter enclosure having a permanent locking arrangement

A tamper proof watthour meter enclosure comprising:

• a base assembly supporting a watthour meter movement, said assembly including plural arcuate attachment lugs extending radially at the outer periphery thereof in spaced apart relationship, said attachment lugs having forward and rear side radial surfaces thereon;
• a plastic cup-shaped cover including a closed forward end and an open end, said cover further including a circular mounting flange extending radially outward at said rear open end, a rear radial side surface of said mounting flange mating with said front radial side surfaces of said attachment lugs, said cover further including a locking rim having a forward inturned flange extending around said mounting flange and further having a cylindrical body portion carrying tab members rotationally attaching said cover to said attachment lugs to enclose said watthour meter movement within a protective chamber;
• a permanent locking arrangement including a hole extending into the rear side surface of the cover mounting flange at a radial position behind said inturned flange so as to have a concealed location thereunder, an aperture in said base assembly aligned with said hole of said cover flange, an irremovable fastener means having a threaded shank portion applied through said base assembly aperture and threadedly attached to said cover flange around said flange hole, said fastener means further having a one-way head portion including a partial screwdriver slot terminating at opposite camming surfaces with said head portion being recessed within said base assembly aperture, and covering means applied to said base assembly over said aperture to conceal said fastener and said base assembly aperture.