How to Test Electrical Receptacles
When troubleshooting, repairing, or replacing an electrical outlet, you'll need to test the receptacles. This ensures there is no power to the outlet before beginning your work. For safety reasons, you should always test electrical receptacles before starting any work to make sure there is no live voltage. Testing electrical receptacles can also help determine if they are functioning properly and identify any potential problems. It is important to make sure your outlets are properly wired and grounded. While an outlet may look like a three-prong, grounded one, for instance, it may not have been properly wired. By discovering these hidden electrical defects, you can prevent damage to your electronics or prevent an electrical fire. Does this Spark an idea?
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Instructions
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Familiarize yourself with how the circuit tester works. This device has two wire leads attached to a small light bulb. When electrical power flows through the wires, the light bulb glows. The circuit tester bulb only glows when it is part of a complete circuit. For example, if one of the leads is touching a hot electrical wire and the other lead is not touching anything else, the light does not glow.
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2
Turn off the power to the outlet at the main electrical service panel box to test electrical receptacles for live power. Ideally your circuits will be labeled and you can just turn off the circuit for the electrical outlet you are working on. If you are not sure which circuit breaker controls the outlet, you may need to cut power to the entire home.
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3
Place one probe from the circuit tester into each slot of the receptacle. When you have a double or quadruple outlet, perform this test for each outlet. This initial test is just to make sure there is no electrical power flowing to the receptacle.
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4
Remove the outlet cover plate by loosening the screws attached to the cover plate and the interior outlet unit. Be careful not to touch any of the wires during this process. Gently pull the electrical receptacle from its wall mounted box. You are now ready to test the actual electrical wires connected to the outlet unit.
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5
Carefully touch one of the circuit tester probes to the brass screw terminal on the side of the outlet unit. Touch the other circuit tester probe to the silver screw terminal on the opposite side of the outlet unit. If you find that wires are attached to both sets of terminals, test both.
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Return to your electrical panel box and turn off the proper circuit if at any point in steps 3 to 5 the circuit tester bulb glows, as there is power to the outlet. If the bulb does not glow, there is no power flowing to the receptacle and it is safe to begin your work.
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7
Leave the power on to the outlet to test a three-slot electrical receptacle for proper grounding. First, take a moment to familiarize yourself with the three-slot outlet. You will find that one slot is shorter than the other. This is the "hot" slot. The longer slot is the "neutral" slot. You will also see a half-oval shaped grounding hole below the two slots.
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Place one probe from the circuit tester into the short (hot) slot of the electrical receptacle. Place the other probe into the half-oval shaped grounding hole. The bulb on your tester should glow. If it doesn't glow, place one probe into the long slot and one probe into the half-oval grounding hole. If the bulb now glows, the hot and neutral wires are reversed. If the bulb does not glow in either test, the electrical receptacle is not grounded. You should take steps to repair either of these problems.
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Place a probe in each slot of a two-slot electrical receptacle to ensure it is properly grounded. Again, leave the power on for this test. The bulb should glow. Remove both probes. Place one of the probes into the short (hot) slot and touch the other probe to the cover plate screw. Be sure the screw is not covered in paint, dirt, or grease. If the circuit tester bulb glows, then your two-slot outlet is properly grounded.
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10
Retest by placing one probe in the long (neutral) slot and touch the other probe to the plate screw if there is no glow when testing the two-slot outlet. If the bulb glows, your wires are reversed. If there is still no glow, then your outlet is not grounded. Either of these problems should be repaired.
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Tips & Warnings
Use caution when working with electricity.
References
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