Loose electrical connections to motor terminals can cause voltage drop, overheating, and a chance of fire. For three-phase motors, a loose connection can cause single phasing — which will damage the motor.

The best connections are with terminal connectors (Figure 1). To attach a terminal connector to a wire, remove about ½ inch of insulation from the wire end. Insert the bare wire into the terminal connector and crimp it on with a crimping tool. Use two crimps to be sure of a good connection. With a hook type connector, be sure that tightening the terminal screw pulls the connector in rather than pushes it out of the terminal.

If the wire is connected directly to the terminal without a terminal connector, follow this procedure:

• Bare 1 inch to 1 ½ inch of wire depending on the situation.

• Use long-nose pliers to bend the wire at 90 degrees (Figure 2).

• Next form a loop (Figure 2).

• Position the loop so that the pressure from tightening the terminal nut or screw tends to push the loop closed — not push it open (Figure 3).

Very rarely, you may encounter an old installation that has aluminum wires instead of copper. If you do find one of these, replace the aluminum wiring with copper. Aluminum wiring creates a greater danger of fire.

Excerpted and reprinted from Top 100 HVAC/R Tips by Leo A. Meyer, one of the books in the Indoor Environment Technician’s Library series published by LAMA Books.

Publication date: 8/5/2013

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