Light Switch Defective

Problem: Switch does not work, works occasionally, or must be repeatedly switched off and on to make light come on.

Background: Correcting a defective light switch is relatively easy, but take proper precautions to avoid electrical shock; make sure the power is off before working on switch. Generally, all you need is a screwdriver and pliers. Though light switches can be wired in a circuit in a number of ways, if you buy the identical switch and wire it exactly the same way as the old switch was wired, you shouldn’t have any problems. Light switches are sometimes replaced when the problem is a burned-out bulb. Even if you have a switch that controls a number of lamps or fixtures, be sure that the bulbs are working before assuming that the switch is defective.
First replace a bulb in a lamp controlled by the switch with one you know works, then work the switch. If the bulb doesn’t light, try to determine if power is reaching the switch. Check the fuse or circuit breaker in the main panel box that feeds the circuit. Replace the fuse or circuit breaker with one you know works, then try the switch again. If it still doesn’t light the bulb, the switch is probably defective.

What to do: To replace a switch, first turn off the power by unscrewing the fuse (or switching off the circuit breaker) or by throwing the main switch to the “off” position. If you are not sure that the power is off, don’t proceed any further until you can get qualified help. With the power off, remove the switch cover plate. Inside you’ll see 2 additional screws that hold the switch mechanism in side the outlet box. By removing these screws you’ll be able to pull the old switch out of the box with the electrical wires still attached. Make note of the color and position of the wires and the screws on the switch.
Double-check to be sure you have the same kind of switch and also note the ground wire (usually green), which may run from the switch to a terminal inside the outlet box. (The ground wire in systems using the newer Romex cable will be a bare wire coming out of the cable.) Loosen the screws holding the wires to the old switch, remove the switch, and attach the wires in the same way onto the new switch. Fasten the switch inside the outlet box, replace the cover, and restore the power.

Special advice: If the new switch doesn’t work, re-check to make sure that the fuse or circuit breaker for that circuit is supplying power. Occasionally a circuit breaker, even a new one, may be defective. Also, though a fuse is of the proper amperage, it may be just slightly shorter than the original, resulting in a power interruption to a particular circuit.

Helpful hint: Hook the loops of the wires under the screw terminals in a clockwise manner so that they remain in position as the screws are tightened. Two-way, single-pole switches will have a screw on each side of the switch. Three-way switches will have three terminals; two will be brass for connecting red and black hot wires, and the third, usually bronze or silver (sometimes black), is for connecting the white neutral wire.