The most important thing to remember about electrical work isn't what wires go where, it's your safety. You absolutely must shut off the power properly before getting to work. Doing this and testing to be sure the power is off is the only way to prevent being dangerously shocked. Besides, it doesn't take a lot of time or effort to avoid a shock—just a little care and a few simple steps. Learn these steps, then make them habits.
Pretend it's live Professional electricians have this simple rule: Even after shutting off power, always act as if the wires are live. That way if someone accidentally turns on the power or a tester gives the wrong reading, you're still protected.
Pretending each wire is live means you should never touch two wires at once. Nor should you touch a wire and a ground at the same time. It is good practice to touch the bare end of a wire only with an insulated tool, not your fingers. As an added precaution, lightly twist a wire nut onto the bare end of any wire that you are not working on—good assurance that it will cause no harm.
Redundant protection Get into the habit of taking the time and trouble to provide yourself with double—even triple—protection. In addition to shutting off power and testing to make sure power is off, wear rubber-sole shoes and use tools with rubber grips specifically designed for electrical work.
Maintain concentration A single lapse of concentration can create a dangerous situation. Eliminate all possible distractions. Keep nonworkers (especially children) away from the work site. Don't listen to the radio or a music player while you work. Check and recheck your connections before restoring power.
Give yourself plenty of time to finish a job. If you need to leave a job and pick it up again the next day, start at the first step: Make sure the circuit is shut off and test for power before proceeding.
Find your service panel. This is most commonly located in the basement of a home or building and looks like a metal cabinet attached to the wall. At the service panel, flip off the breaker or unscrew the fuse controlling the electrical box or device you will work on. To make projects in the future easier, consider labeling your switches so you know what rooms they control.
Test for the presence of power using a voltage tester. To do this properly, follow the manufacturer's instructions. If you are working on a receptacle, test both plugs.
It's a good practice to test the tester, too. Touch the probes to a live circuit to make sure the indicator bulb lights are working properly.
A single box might have more than one circuit running through it. Carefully remove the device or fixture, unscrew the wire nuts, and test all the wires for power using a probe-type voltage tester. Follow the manufacturer's instructions when doing this.