The part of a light fixture that the bulb screws into is called the socket and is in all lamps, hanging fixtures and even ceiling lights. Over time, the sockets can malfunction, causing the light bulb not to work. In these instances, you can replace the socket with a new one to restore the electrical circuit. Installing a new light bulb socket is a straightforward process once you understand the basic parts of a light fixture.
Unplug the light from the electrical socket if the fixture has a cord. If the light does not have a cord, such as a ceiling light, turn off the power to the light at the house's main fuse box or circuit breaker.
Unscrew the bulb from the light and remove the light shade or glass dome. Most table and floor light shades simply lift off, or have two metal arms on the bottom called a harp, which you squeeze to remove. Installed lights have a centre metal cap that unscrews and allows the glass dome to come off.
Squeeze the base of the socket cover and lift up to remove it.
Pull the insulation cover, which is typically ceramic, straight up out of the light socket to remove it.
Look into the centre top of the socket and locate the screw that holds the socket to the lamp. Remove the screw with a screwdriver.
Grasp the socket itself and pull upward with firm pressure until you see the wires underneath it. Cut the wires off directly under the knotted area using diagonal wire cutters.
Loosen the two screws on the bottom of the socket with a screwdriver to release the wires from the socket.
Insert a new socket base into the top centre of the light and pull up the two wires through the centre of the socket base.
Insert 3/4 inch of the end of each wire into a wire stripper and remove the plastic coating. Tie the two wires together in a knot.
Wrap the end of the smooth wire around the brass screw on the light socket and secure it with a screwdriver. Wrap the end of the ribbed wire around the silver screw on the light socket and secure it with the screwdriver.
Secure the screw in the centre of the socket with a screwdriver to hold it in place.
Push the socket into the base assembly and insert the insulating sleeve into the top of the socket. Slide the new cover on top of the entire assembly and screw in a new light bulb.
Replace the lamp harp and lampshade and plug the cord into an electrical socket, or turn the power back on, to test the new socket.
Examine the wiring closely while the socket is removed. If it is frayed or has burn marks you should replace it as well. To tie a knot, create a loop with each wire and pull the free end of the wires through the opposite loop until tight. This is called an underwriter's knot and prevents the wires from slipping out of the socket screws.
Never try to replace a light bulb socket without unplugging the light or turning off the power supply first.