Abstract: A floor box wiring fitting incorporating a novel carpet flange possessing a self-closing flap cover assembly, whereby the fitting is adapted to be cast into a concrete floor of a building for the conductance of electrical power or telecommunication signals between the work spaces of buildings. The self-closing action of the flap covers which are hingedly connected to the flap cover plate structure, the latter of which consists of a carpet flange, is essentially implemented through an angular operative contacting relationship between the wall surfaces of the openings receiving the hinging portion of the flap covers and the contiguous or adjacent wall surface of the flap cover which, in effect, will inhibit the flap covers from being opened or swing upwardly from a closed horizontal position to an acute opening angle greater than about 85.degree..