How to Wire a Contactor: 8 Steps (with Pictures) - wikiHow METHODWARNINGSTHINGS NEEDED Acquire the contactor. Make sure that the contacts of the contactor are rated in both voltage and current to handle the expected load that will be required by the equipment being powered. Contactors are available from building and construction supply stores, as well as some larger hardware stores.Study the contactor manufacturer information. The manufacturer information will identify the 2 input pins for 120 volts AC control. The may be 2 or more sets of output contacts identified. These contacSee all 8 steps on wwwhowViews: 247K How to Wire a Contactor With a 120 Volt Coil | Hunker The main advantage in using a contactor is that the switch can be powered by a different and lower power source from the main contactor power supply. In other words, a 120 volt alternating current (commonly referred to as a 120 VAC) is wired to the coil of the contactor.