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How to Use a Multimeter to Test an Outlet

Person's right hand holding a multimeter while the left hand holds a meter probe to an electrical outlet.

Need to troubleshoot a dead outlet? Then you need a multimeter. This helpful device can help you test outlets, cords, light strands, bulbs, and more by measuring the flow of electricity. You can use it to determine if an outlet is dead or experiencing an unexpected issue while still delivering electricity.

Not sure how to test an outlet? Read on; we’ll show you how to use a multimeter to test an outlet and explain the other functions of this helpful tool.

  • What Can a Multimeter Tell You about Outlets?
  • How to Test an Outlet with a Multimeter in 7 Simple Steps

What Can a Multimeter Tell You about Outlets?

Multimeters are electrical current measurement devices that can help you understand the resistance, current, and voltage of circuits, such as those in outlets, by injecting a small charge into them. The charge is then measured on its way back to the multimeter to diagnose various issues inside the circuits.

A multimeter can help you determine:

  • If power is reaching an outlet
  • If the outlet is properly grounded
  • Whether wiring within the outlet is reversed

This tool measures three different electrical values: voltage, amps, and ohms. By learning how to read these outputs effectively, you can determine whether your outlet is functional. If it is broken, multimeter readings can show you what has rendered it non-functional.

How to Test an Outlet with a Multimeter in Seven Simple Steps

Multimeters are widely available and inexpensive tools, but if you don’t know how to read them, you won’t get much out of them. Here’s a seven-step guide detailing how to use a multimeter to test an outlet:

  1. Learn the essentials of outlet testing safety.
    Because you must perform these tests on a live outlet, ensure your safety by holding both meter probes in the same hand. This will prevent shock from passing through your body. It’s also a good idea to wear rubber gloves as a precaution in case you lose your grip on the meter probes. Never allow the metal portion of the probes to brush each other or touch, as this can create a dangerous short circuit.

  2. Get to know outlet geography.
    Modern outlets have three slots: one for hot, one for neutral, and one for ground. The rounded half circle is the ground, the longer slot (left) is the neutral, and the shorter slot (right) is hot. Remember that all the wires can carry current, so handle them cautiously.

  3. Adjust your multimeter.
    Set your meter to measure voltage. Select the alternating current (AC) function on the multimeter, which is often labeled with a wavy line. The direct current (DC) function will have a solid line and a dashed line.

  4. Connect the leads.
    Push the short, thick connector (called a banana plug) of the black lead into the connector labeled ‘COM’ (it may have a minus “-” sign beside it). Then, plug in the red connector labeled with a “+” or “Ω” (the Greek letter Omega).

  5. Measure the voltage to determine if the outlet has power.
    Using one hand, insert a probe into each vertical slot on the outlet. Red goes into the smaller slot, and black goes into the larger one. A properly functioning outlet will give a reading of 110–120 volts. If there is no reading, either something is wrong with the wiring in the outlet or the circuit breaker is tripped. If the outlet is connected to a light switch, make sure the outlet is on and capable of being tested.

  6. Determine if the outlet is properly grounded.
    Keep the red lead in the small slot and place the black lead in the ground (U-shaped) outlet slot. The reading should remain the same. If it doesn’t, the outlet is improperly grounded.

  7. Check if the wiring is reversed.
    Place the red lead into the large slot and the black lead into the small slot. If you get a reading, the wiring is reversed. This won’t affect simple equipment like lamps but can cause issues for more sophisticated appliances and electronics.

If your outlet provides no current or has any other issue, contact a qualified electrician to address the issue. Attempting to do wiring work alone can lead to fires, electrocution, and other hazards.

Count on Mr. Electric for Safe, Prompt Electrical Service

Need to resolve your outlet issue? Avoid a hair-raising electrical experience. Your local Mr. Electric® will be happy to help with any electrical projects you’ve been putting off. Whether you need to replace an existing outlet, install a new outlet, or upgrade to a GFCI outlet, our experts can handle your needs. Contact Mr. Electric today to schedule an appointment online.

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