Working Safely with Electricity: Testing Two-Slot Receptacles

The most essential step to avoid serious injury is to turn off the power at the main service panel before touching any wires. If your work involves one circuit, determine which fuse or circuit breaker protects the circuit and remove that fuse or throw that breaker. If you are unsure about which fuse to remove or breaker to throw, or if there is a chance that more than one circuit is involved, remove the main fuse block or throw the main breaker.

After turning off the power to the circuit you will be working on, use a voltage tester, an instrument that indicates whether or not voltage is present, to be certain the circuit is definitely off. If the voltage tester lights up or otherwise shows that a circuit is hot, you have not removed the right fuse or thrown the right breaker. Redetermine which fuse or breaker protects that circuit or shut off the main, and test the circuit again before proceeding.

A defective voltage tester may not light, which is the same indication as when no voltage is detected. Always check your voltage tester in a live receptacle to be sure it is operational before putting your faith in it.

Once the power is off, your working conditions are much safer but precautions must still be taken. Never work on or near live power. Use only Underwriters' Laboratories (UL) listed appliances and electrical supplies.

One of the most important things to know is when to call a licensed electrician. Pick up the phone if you are unsure of your abilities; if your service panel is hot, sparking, making cracking noises, blackened or rusted; if you smell something burning; if extensive repairs are necessary and you are not familiar with local code; or if you begin working and encounter something unusual. These are the times to call a professional.

To determine which fuse or circuit breaker protects a receptacle you are working on, plug a radio into the receptacle and turn the volume up. At the main panel, remove fuses or switch off the breakers until the radio is off.

Your main service panel may be a circuit breaker box or a fuse box. To locate the panel, find your electric meter outside your home, then check the inside wall where the meter is located. Determine which breaker or fuse protects the circuit you are working on, then turn off power to that circuit by throwing the breaker or removing the fuse. Check with a voltage tester to ensure power is off before attempting any electrical repairs. Label each active breaker once you have determined which locations or appliances it controls.

Testing Two-Slot Receptacles:

You will need a screwdriver and a voltage tester.

Check that your voltage tester works: With the power on, insert one tester probe into each receptacle opening. If tester lights, receptacle has power and tester is operating properly.

Turn off power and repeat step 1, placing one tester probe into each receptacle opening. The tester should not light if the power is off.

As a final check, place tester probes against bare ends of black and white wires at all four screw terminals, where wires are attached to receptacle. Remove receptacle only if tester indicates that power is off.