By following a relatively basic step-by-step process, you can connect an electrical contactor in a matter of minutes. Contactors employ two distinct devices for their operation -- an electric coil solenoid and a set of conductive contactors. The coil solenoid is controlled by a separate control voltage. When power is applied to the control coil it engages the contactors to energise the device it is attached to for operation.
Mount the contactor in a code-approved enclosure as provided by the manufacturer or by following state or local electrical codes. Use the mounting screws that are supplied by the manufacturer of the enclosure or the contactor, and the appropriate screwdriver.
Strip all the wires that will be connected to the control coil and the contactor terminations with the wire strippers. Remove approximately ½ inch of the wire's insulation to expose the bare copper wire.
Connect the control wires to the coil solenoid first by loosening the termination screws with the appropriate screwdriver. When installing the wires, be sure that a good electrical connection is made while tightening the screws. If the wire is of the stranded type, gather any errant strands of wire under the screw so the loose strands do not short against any metal part on the control coil.
Terminate the device feed wires, first to the terminals marked "T". Depending on the number of contactors on the unit, the identification can read as follows, "T1", "T2", and "T3". If you are using only one set of contactors, it is good wiring practice to begin with the first terminal on the left hand side of the contactor -- this is generally "T1".
Connect the power feed wires to the top side of the contactor to the terminals marked "L". These too will be marked in the same numerical order as in step 4 above --"L1", "L2" and "L3". Match the input and output side of the wires if you are using fewer than the number of contactor terminals provided for the wiring you are connecting.
Follow all state and local electrical codes whenever servicing or installing any electrical devices. Pay particular attention to amperage and voltage ratings when installing any type of contactor.