When power cords won't stay in an electrical outlet and simply fall out on their own, its time to replace the worn out outlet. Outlets eventually wear out over time, or more quickly if misused. Pulling a plug out of an outlet by its cord, while vacuuming for instance, can damage the outlet internally. But a loose power cord is more than an inconvenience -- it can create an electrical hazard. With the plug loose in the socket it allows the electricity to arc, or jump the gap, which causes the outlet and wires to heat up and potentially cause a fire. The metal tabs inside an outlet are a preset distance apart and provide a good grip on a plug that's inserted into the outlet. After time, or misuse, the metal can bend and distort, allowing anything plugged into that socket to fall out on its own. You can prevent power cords from unplugging by replacing the bad outlet.
Plug a lamp into the electrical socket that needs to be replaced. Use the switch on the lamp to turn it on. Turn off the breaker in the electrical panel box that controls the outlet. When the correct breaker is turned off the lamp should turn off.
Unplug the lamp when you have verified that the power is off on the outlet. Remove the screw holding the cover on the outlet with a straight screwdriver. Loosen the two screws that hold the outlet into the electrical box.
Pull the outlet and wires out of the electrical box so that all the connections are visible. Loosen all the screws holding the wires onto the outlet, and pull the wires off. Install the new duplex receptacle, or outlet.
Hook the black wire or wires around the brass screws on the outlet, with the open end of the hook on the right side of the screws so that the wire doesn't uncurl when you tighten the screw.
Hook the white wires around the silver screws on the outlet, again with the open end on the right. Hook the bare, or green, wire around the green grounding screw on the outlet. Tighten all the screws down.
Push the wires and outlet into the electrical box. Screw in the two screws that hold the outlet into the box. Place the outlet cover onto the outlet and screw in the single screw that holds it on. Turn the breaker back on.