A rusty light socket can cause all sorts of problems. Unfortunately, outdoor light sockets are frequently exposed to moisture from rain, dew, and melting snow. Add electrical current to the mix, and you've got a recipe for corrosion. A rusty light socket will diminish the flow of electricity between the socket and the bulb, will make bulb removal difficult, and can lead to unsightly stains on concrete and siding. Prevent these problems by removing any rust build-up and preventing future corrosion.
Unplug the light fixture or disconnect the circuit breaker to cut power. Whenever you are working with an electrical fixture or appliance, be careful. Disconnect the power first to prevent any injuries or mishaps.
Remove the bulb. Often a bulb will get stuck in a light socket because corrosion build up inside the socket prevents the bulb from unscrewing freely. If the bulb sticks, carefully work the bulb back and forth, twisting both clockwise and counterclockwise to loosen the threads. Apply a bit of WD-40 to ease the process. If the bulb breaks, it can still be removed by pressing a raw potato or apple into the base, and then twisting.
Assess the damage to the socket from corrosion. In most instances, there will be only a little rust inside the socket. Sometimes, however, the socket will be so damaged that it must be replaced. If the corrosion has eaten holes in the metal, fully coats the inside surface, or significantly alters the shape of the screw threads, you may be better off simply replacing the socket entirely.
Soak the corroded area with white vinegar. Wet a rag or paper towels with white vinegar. Apply the damp rag to the rusted surface, and let sit for several hours, occasionally rewetting the rag with vinegar. When done, use a rag, a plastic scrubber, or steel wool to wipe or scrub away as much loose rust as you can.
Scrub the light socket using a baking soda paste. This paste is made by mixing baking soda and water, adding just enough water to make a thick paste. First dry the light socket completely to prevent a reaction with the vinegar. Then, using a toothbrush or similar scrubbing tool, apply the paste and scrub. Continue scrubbing until all rust has been removed.
Prevent future corrosion with a light lubricant. Applying a coating of WD-40 or similar lubricant to the interior of the light socket can prevent future corrosion. Additionally, you might consider using a lubricant designed especially for light bulbs, such as Bulb EZ.