As a standard, the tunnel demagnetisers are designed for continuous duty. The model DEM T9 permits either continuously duty withh push-button "Start-Stop" control, or intermittent duty, in which case operation is effected by a 0/66 second automatic time switch. A thermostatic, protection for the coil ensures complete safety. Furthermore, the tunnels can be designed, upon request, for use with two different working conditions: continuous duty or high powered with intermittent duty.