Abstract: An electrical connector housing element includes passages each receiving an electrical contact and a system for locking them. The passages are in two series each comprising two rows. The locking system includes two keys in a head-to-tail arrangement and each of which is U-shape with two branches and a core. Each key is mounted so that one of its branches lies between the branches of the other key. Inclined guides are provided in a groove whereby each key can move in the groove in two perpendicular directions. In a locking position the two branches of the first key immobilize the electrical contacts of the two first rows of the two series of passages. In the locking position the two branches of the second key immobilize the electrical contacts of the two second rows of the two series of passages.