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This article is written for a standard, grounded US outlet. If your home does not have grounded outlets just disregard the part about the ground wire. This outlet is called a duplex receptacle because it has two places to plug in appliances or lamps.
One very important piece of information will need to be determined before you turn off the power and begin is whether this a regular outlet where both plugs are always on or switched OR is this an outlet where one plug is switched and the other is always on (a split duplex outlet). To eliminate confusion we chose to split this article into two articles. If you have a standard duplex outlet continue reading this article.
You won't need many tools to perform this job and none of them are expensive in most cases a flat and Phillips screwdriver are all you need. Occasionally you will need a pair of pliers to reform the loop of wire (terminal loop). Also sometimes you will need a very small flat blade screwdriver if the device has been wired using the pressure terminals on the back of the device.
Turn off the power and then verify that the power is off to both halves of the duplex receptacle by plugging in a known working lamp or using a circuit tester. Then remove the device box cover. Under that you will find two more screws near the top and bottom of the box that actual hold the device in place. Remove those and gently pull the device towards the room. Until you have access to the terminals to which the wires are attached.
There are a couple of important things for you to check out at this time:
How many wires are attached to the device; three or five?
Three wires, one white and one black and one bare or green would be a standard grounded 115 volt outlet. Five wires, two whites and two black plus a green or bare wire indicates that this outlet feeds another device.
Two wires, one white and one black would indicate an ungrounded 115 volt outlet. Four wires, two white and two black would indicate an ungrounded 115 volt outlet that feeds another outlet.
Polarity is Important!
All modern devices go out of their way to make sure you follow the correct polarity. The screw terminals have been color coded for many years; but now the back of the devices are imprinted with the standard wire color information. The hot, black wire(s) is attached to the gold screw and the neutral, white wire(s) is attached to the silver screw. The green or bare is attached to the single, green screw.
No wire attached to screws?
Sometimes devices are wired using push in terminal on the back of the device. These wires are released by pressing in the small metallic tab and then pulling on the wire. Personally, I never use these connections. I always use the screws.
A three wire receptacle is hard to mess up as long as you keep polarity in mind, but this is a good time for you to learn good work habits. Take one wire at a time loose from the old device and connect to the new device.
The wires should have a neatly formed loop that looks a lot like a question mark except the loop should be a bit longer. That loop should be placed under the screw so that the open side faces in a clock-wise direction. The reason is so that the wire will be pulled to the screw as the screw is tightened.
Once you have all the wires are connected gently bend the wire so that the device can be properly seated in the box, replace the cover and turn on the breaker. Test for proper operation.