A.Sean Kenney responds: Whenever I go on a residential service call where the power is out in a receptacle or a portion of a room, 75% of the time the problem is caused by a failed push-in terminal on a receptacle or switch.

Push-in terminals are small copper spring clips that only make contact with a small portion of the wire. When a push-in terminal is subjected to a high-amperage draw, the terminal often overheats, eventually causing the connection to burn out. Another problem is that when the electrician pushes the receptacle or switch into the box, the wires twist and bend, putting a lot of stress on the relatively weak spring clips.

The National Electric Code ( NEC) has restricted the use of push-in terminals to #14 AWG copper wire only. Even though the push-in connectors are quicker and easier to use than the screw terminals, I never use them, nor do I allow my employees to use them.

Some ground-fault circuit interrupter (GFCI) receptacles have clamp-style terminals that are almost as easy to use as push-in terminals. The wire is pushed into the back of the GFCI and a screw is tightened to secure the clamp. Many higher-grade receptacles and switches have a similar clamp terminal. These terminals make a good connection, but as with any terminal, the wire should be given a tug to make sure the connection is tight.

Sean Kenney owns and operates Sean M. Kenney Electrical in Amesbury, Mass.