shaft module 3 the water level 26 in the housing no longer rises as shown in fig4 thus even if the entire inner space 6 is flooded with water 24 the water 24 does not rise up to the supply unit 16 preferably in the area outside the housing 19 a ventilation device can be provided through which the air displaced by the water 24 when the water level 25 rises outside the housing can escape from the inner space 6 for example the coil unit 9 has a one way valve 27 that allows air and optionally also water 24 to escape from the inner space 6 but does not permit air or water to penetrate into the inner space 6 in the opposite direction also a not shown closeable exhaust opening can be provided in the device 1 to be able to easily suction from the outside water present in the inner space 6 of the shaft module 3 for example a closeable round hole above the inner space 6 outside of the housing cover 21 could be provided in the coil unit 9 by means of which a hose can be inserted into the inner space fig5 shows the device according to the invention from fig1 with a housing 19 u2032 with another alternative housing shape identical parts as in the design shown in fig1 are provided with identical designations and given identical reference symbols a housing wall 23 u2032 narrows from the housing cover 21 toward the housing opening 20 u2032 so that.