A low water sensor within the vessel is connected to a relay coil with contacts interrupting the flow of electrical energy to the heating element when {HEAD ~ water} is beneath {TAIL ~ the level} of the sensor 
is beneath
A low water sensor within the vessel is connected to a relay coil with contacts interrupting the flow of electrical energy to the heating element when { HEAD ~ water } is beneath { TAIL ~ the level } of the sensor
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH