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