The Merlin CS1 Current Monitor is a single fan current monitor and is to be used in conjunction with the Merlin range of kitchen ventilation interlock systems; it can be used as an alternative to an air pressure differential switch. The Live wire running between the fan controller and the fan goes through the hole and is to be looped around the coil to increase sensitivity. When the fan is running and a current is being drawn along the live feed, a magnetic field is induced through the coil and the current switch will send a closed contact along two low voltage cables to any Merlin Gas Interlock System.
 
Ventilation interlock system which isolates the fuel supply if the ventilation fails