An electrical apparatus that can be fixed to a supporting frame having a
mounting window to receive the electrical apparatus includes a main body
having a substantially box-like shape and first fixing elements provided
on first and second opposite sides of the body to engage with
corresponding second fixing elements the frame and facing the mounting
window. The first fixing elements include guiding fixing elements to
permit axial and guided sliding of electrical apparatus with respect to
the frame in inserting the apparatus into the mounting window. The first
fixing elements further include snap-in fixing elements to block axial
sliding of the electrical apparatus with respect to the frame once a
predetermined snap-in position has been reached.