ULW UL Recognized Wirewound Resistors Welwyn / TT Electronics ULW UL Recognized Wirewound Resistors are fusable resistors with failsafe AC fusing at 120VRMS / 240VRMS, inrush and surge withstanding. With a UL940V0 flameproof coating, the ULW Series offers power ratings of 2W to 5W. Welwyn / TT Electronics ULW UL Recognized Wirewound Resistors are available SMD and are RoHS compliant.