Abstract: An electrical installation device for fastening in an attachment position on a carrier rail includes an instrument housing made of insulating plastic and having an instrument housing wall and a bottom facing the carrier rail in an attachment position. A sliding latch is shaped in one piece to the instrument housing wall and is movable in a locking direction outside of the housing bottom transversely to the attachment direction and to the carrier rail direction. A flexible web, spring elastic in the locking direction, is connected between the sliding latch and the instrument housing wall. A detent lug is attached to the sliding latch and, in the locking direction, grips behind the carrier rail. An actuating end is connected to the flexible web and faces away from the detent lug, whereby the sliding latch is returnable against the spring elasticity of the flexible web from a locked position into a release position by actuation of the actuating end.