Abstract: An electrical switch having a double liquid medium immersion sensing function is disclosed. The switch (121) particularly includes a battery (125) connected to a power outlet (126) via an electronic circuit (124) that only connects the battery to the outlet once a first pair of electrodes (131, 132) have sensed immersion in a predetermined medium, and a second pair of electrodes (133, 134) connected to a pressure sensor (135) have sensed a predetermined immersion depth. Said switch (121) is advantageously connected to a pyrotechnic device (75) for inflating emergency equipment such as life jackets.