Abstract: An electric lamp is provided with an end having an annular recess which contains an insulating member which is secured to the lamp by means of at least two conductors which each extend from the lamp through an aperture in the insulating member. The insulating member and the annular recess are so shaped that the insulating member is held against rotation and lateral displacement with respect to the lamp. The insulating member has cut-out portions remote from its ends, preferably in a central portion, and most preferably configured to have two substantially octagonal portions connected by a portion in the shape of a rectangle, through which cut-out portions underlying material of the annular recess is exposed.