Field Controls 46082700 TCA-1 Thermal Safety Switch Thermocouple Adapter Right Hand Thread Used On: 30mV Gas Valves With Right Hand Thread This device is used to attach spill switches to a 30 millivolt water heater. It is designed to be used with GSK SERIES spill switches, TSP SERIES spill switch, or SSK SERIES spill switch kits for connecting flue gas sensing spillage switches to 30 millivolt gas valves.