Screw connection for fluorescent light fitting - provides both electrical and mechanical connection using knurled nut penetrating paint to provide contact

摘要

Screw connection providing an electrical and a mechanical connection of the metal parts of a lamp at least partially coated with an electrically insulating layer of paint. The connection is made between a lacquered carrier for the lamp accessories and the holding rail for a fluorescent tube unit to be earthed through a knurled nut which during tightening penetrates the electrically insulating paint layer making an electric contact with the metal element below. The element creating the electric contact consists of a cutting ring (20) co-axial to and made in one piece with at least one top surface of the nut and having a sharp cutting edge (21). The screw connection relative to the metal sections (11, 12) is arranged so that at least one of the metal sections (11) is elastically deformable during the tightening of the nut (18) to ensure that the return force maintains the contact pressure with the nut secured by friction closure.