How to Wire a Contactor: 8 Steps (with Pictures) - wikiHow Views: 267K Acquire the contactor. Make sure that the contacts of the contactor are rated in both voltage and Study the contactor manufacturer information. The manufacturer information will identify the 2 input Check for an auxiliary output contact. Some contactors provide an auxiliary output contact as a Route the wires. Remove all power to the wires. Run all input and output wires to the contactor. See all full list on wikihow How to Wire a Three-Phase Contactor | Hunker A three-phase contactor is an electronic device used to turn power on or off at a three-phase load. These devices are used when the voltage requirements of the load exceed the power-handling capability of a mechanical relay. Contactors are typically used on three-phase air conditioning motors requiring at least 480 volts to operate.