How to Test Electrical Receptacles

When troubleshooting, repairing, or replacing an electrical outlet, you'll need to test the receptacles. This will help to ensure 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. Many times the wiring to an electrical outlet will be reversed without the home owner's knowledge. A homeowner may believe his outlets are grounded, when in reality the three-slot receptacle has not been properly wired. By discovering these hidden electrical defects, you can prevent damage to your electronics or prevent an an electrical fire.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Neon Circuit Tester
• Screw Driver
• Flashlight

1. 
   Neon Circuit Tester

   Purchase a neon circuit tester. The circuit tester can be used for a number of different tests. They are inexpensive and should be part of everyone's tool kit.

2. 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 will only glow 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 will not glow.

3. To test electrical receptacles for live power, the process is essentially the same for any type of outlet. Begin by turning off the power to the outlet at the main electrical service panel box. 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.

4. Return to the electrical outlet to begin your test. 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.

5. 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.

6. 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.

7. If at any point in the above steps 4-6 the circuit tester bulb glows, there is power to the outlet. You need to return to your electrical panel box and turn off the proper circuit. If the bulb does not glow, there is not power flowing to the receptacle and it is safe to begin your work.

8. 
   Three-Slot Outlet

   You can also use the neon circuit tester 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.

9. For the grounding test, you will leave the power on to the outlet. 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.

10. You can also test a two-slot electrical receptacle to ensure it is properly grounded. Again, leave the power on for this test. First test to be sure there is power to the outlet by placing a probe in each slot. 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.

11. If there is no glow found when testing the two-slot outlet in step 10, test again by placing one probe in the long (neutral) slot and touch the other probe to the plate screw. 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.

Resources

• eHow Home and Garden Topic Guide

[Surfthetide]

on 6/11/2009 Many times a neon circuit test will glow full bright when only one lead is touched to a hot wire. It will always glow when you touch one lead to a hot wire and hold the other lead in your hand. This is because the extremely high impedance and low burden of the neon light will complete the 60Hz circuit throught the capacitive coupling of the human body to the earth (zero potential plane). A low impedace device is much less confusing for some of the tests you describe. I carry a standard medium base pigtail socket with a 7.5 watt incandescant lamp in my tool box. A non-contact or inductance voltage tester is also useful.

[veryirie]

on 5/25/2009 You forgot to add, "if the bulb is glowing, you better make sure you're not standing in water". ha Sorry, my husband is an electrician and I couldn't resist. :) Very thorough article; well done!