Changing or replacing a light switch in your storage shed may be necessary if the existing switch goes bad or you want to install a different style of switch. Learning how to replace a switch is a simple storage shed or home improvement project that will save you the cost of hiring an electrician to do the work for you.
Single pole light switches are very simple circuits. They have 3 screw "terminals" on them.
The power comes into the switch and is either allowed to go out to the lights or stopped by the switch, depending on if the switch is on or off. It does not matter which terminal either of the power wires is connected to so you do not need to remember which wire is the power leg coming in or out when you take the switch off the wires and put the new one on.
Light Switch Wiring with power coming from the switch.
Light Switch Wiring with power coming from the light
The electricity will pass through a breaker or fuse before going to the light switch. The breaker or fuse will be in a metal breaker box or electrical service panel that is on one of the interior or exterior walls of the shed or house. Find the breaker or fuse that feeds power to the light switch and turn it off. Alternately you may turn the power off to the whole breaker box panel by going to the fuse or breaker that feeds electricity to the breaker box and shutting the main breaker off.
Use the flat head screwdrive to remove the two screws holding the cover on.
Since one of the reasons that you may be replacing the switch is because of a faulty switch you may not be able to trust that the switch is working and therefore not know if the power is on or off by flipping the switch. Use a circuit or proximity tester to test that the power is off before removing the switch. Test the tester on a circuit that you know is live to make sure it is working properly.
The switch is held onto the "handy box" in the wall by two screws. Remove the two screws and pull the switch out of the "handy box".
NOTE When pulling the switch out of the box, never touch the screw terminals on the sides of the switch, these screw terminals hold the electrical wires and may or may not be energized. You should make it a practice to not touch the terminals with bare hands, even if you think the power is off.
Determine how the wires are attached to the old switch and remove them:
If the wires are attached to the old switch using the slip in connectors you will need to cut the wires to get them off the switch, or some switches have a little hole that you can push a piece of wire into and release the wires going into the switch.
If the wires are attached to the old switch using the screw terminals then remove the wires from the switch by unscrewing the three terminal screws holding the wires onto the switch.
Professional Electricians recommend attaching the wires to the switch by using the screw terminals on the side of the switch. The screw terminals are more secure at holding wires than the slide in connectors found on the backs of many light switches.
The switch will have marking on it designating "ON" and "OFF" positions.
Put the electrical switch cover plate using the two screws that held it on when you took it off. Be careful to not overtighten the face plate as they are prone to cracking when the screw is overtightened. Watch the face of the cover plate as you tighten the screws, stop tightening when you see the face start to bend.
Return to the service panel or breaker box and turn the power back on. Once the power is on go to the switch and test that it is working properly.