The contact safety mechanism used by Brennenstuhl® locks when the plug is not inserted correctly – because that is precisely what it is designed to do. So, what is the correct way to do it? Only when both plug pins are pressed simultaneously and with equal force on the plastic sliders does the safety mechanism open and the electrical appliance can be plugged in. So if you have this problem again and a plug does not fit properly into the socket, you must make sure that it is inserted as straight as possible and as gently as possible. A little pressure is needed, but one thing is clear: if the mechanism blocks, do not use force when plugging in an electrical appliance. Because a damaged contact protection is itself a source of danger.