Contactors and overload relays combine to create motor starter assemblies. Contactors have multiple pole connections to open and close several circuits at once. Overload relays monitor for overcurrent and phase failure to protect against overheating and damage. IEC contactors and IEC overload relays are made to International Electrotechnical Commission standards. NEMA contactors and NEMA overload relays are made to National Electric Manufacturers Association standards. Definite purpose contactors have specific performance ratings for low life-cycle applications like HVACR. Lighting contactors turn banks of lights and signs on and off. Safety contactors monitor operational and environmental conditions and cut off power to protect workers. Mercury displacement contactors open and close circuits in dusty and oily locations.