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...

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