Abstract: When screwing in a bulb into the lamp-holder according to the invention, which is carried out in an axially somewhat movable, threaded yoke (4), initially, via one of two resilient contacts (20, 21) associated with contacts (19) provided on an outer plate (15) which is somewhat movable wth respect to the yoke, the outer plate and an inner plate (9) provided with a pair of contacts (12) and immovable with respect to the yoke, are pressed towards each other until a stop (7a, 7b) on the lamp-holder housing (1) arrests the outer plate or the yoke before the pairs of contacts are brought together. By the continued threading motion of the bulb and by the fact that now the outer plate or the yoke are immovable with respect to the housing the plates are moved towards each other until their contact pairs are brought together and the yoke or the outer plate is arrested by the said stop. The contact pairs cannot be brought together by an object without it cooperating with the thread (5) of the yoke.