How to measure AC voltage with a multimeter.

A picture showing a multimeter an instrument that you can use to measure AC voltage.

How to measure AC voltage with a multimeter, is a question that I see a lot of people ask me. How do you measure AC voltage with a multimeter?

I am going to share with you the process that I use when measuring AC voltage. Before I review the method that I use in measuring AC voltage, allow me to explain what is AC voltage.

What is AC voltage?

In simple terms, AC voltage is alternating current. This simply means that the voltage changes its direction several times per second. This is why there are power distribution systems like 120V 60Hz and 220V 50Hz.

The frequency in these power distribution systems, tells you how many times the voltage changes its direction per second.

It is easy to produce power in AC form than it is to generate DC (Direct Current). For this reason, most electrical appliances and machines, both for domestic and commercial use, operate using AC voltage.

Therefore, I think it is useful for me to share with you the steps to take when measuring AC voltage. In the next paragraph, allow me to highlight safety precautions that you must observe when you want to check the voltage with a multimeter.

Safety precaution of multimeter.

Safety is everyone’s responsibility but ultimately it is in your hands. Therefore,here are the safety tips you should follow when using a multimeter.

  1. Work on de-energized circuits whenever possible.
  2. On live circuits, use protective gear.
  3. Use insulated tools.
  4. Wear safety glasses or use a face shield.
  5. Wear insulated gloves, remove jewellery and watches.
  6. Stand on an insulated mart.
  7. Wear flame-resistant clothing.
  8. When making measurements on live circuits. Use the three-point test method especially when checking to see if a circuit is dead. First test a known live circuit.
  9. Second test the target circuit.Third test the live circuit again this verifies that your meter worked properly before and after the measurement.
  10. When you are measuring current, connect the multimeter in series with the component or device you are measuring.
  11. When you are measuring voltage, connect the multimeter in parallel with the component or device you are measuring.
  12. Make sure you switch off power to a circuit when you are measuring resistance.

Parts of a multimeter.

In order for you to use a multimeter safely. You should know the three basic parts of a multimeter that will help you to measure AC voltage. Below is a list of the three basic parts of a multimeter that will help you to use a multimeter.

  1. The display.
  2. Selector Knob/Dial.
  3. Probs.

The display

This is where the value of a measured quantity is displayed or shown. It can be current in amperes, the voltage in volts, resistance in ohms or frequency in Hertz.

Selector Knob/dial

The sole function of the selector knob is to allow you the user of a multimeter. To navigate through the different functions or meters of the instrument. For example, if you want to measure voltage. You use the selector knob to select the voltmeter on the multimeter.


The probs are the two leads cables that help you to measure the selected component. It can be voltage, current and any desired electrical function you would want to measure. Probs are a connecting link between the multimeter and the device you want to measure.

Step by step guide on how to measure AC voltage with a multimeter.

When you want to measure AC voltage. You move the selector knob to the AC voltage setting. Some multimeters have auto range, this entails that you don’t have to select the voltage range manually

Here are the steps you should take when measuring AC voltage.

  1. You need to power off the circuit. You do this in order to reduce the danger of a short circuit, especially when you are working on a three-phase system.
  2. Put the black probe lead into the socket labelled com on your multimeter
  3. Plug the red probe lead into the socket labelled V.In most multimeters, this socket is also marked with omega and diode symbols.
  4. Make sure your multimeter is connected in parallel with the load that you want to measure voltage.
  5. Touch the black probe against the first point you want to measure.
  6. Then you power the equipment.
  7. Touch the red probe against the second point that you want to measure.
  8. Then take the reading on the LCD display of your multimeter.

Generally, a voltage test is conducted on a live circuit. Why would you want to measure the voltage in a home? or any other electrical installation.

In a home setting, you can measure AC voltage when you notice that in the same home some appliances are working and others are not.

Mostly you want to ascertain, whether the appliance not working is faulty or the power from the supply is not reaching the appliance.

At times you will find that power is reaching the appliance but it is not operating normally. When you are measuring voltage using a multimeter, you want to know the exact voltage being supplied to the appliance.

This test will indicate to you whether there is a low voltage or not. A voltage test is very useful when you want to know the voltage status. It is important to know the voltage being supplied because some electrical and electronics appliances and machines will not operate when you have low voltage.


While it is important to measure AC voltage with a multimeter, I strongly advise you if you are not equipped with basic electrical engineering skills, don’t attempt to measure voltage with a multimeter. You are better off using a contact neon test.

When you are using a contact neon tester, the risk of electrical damage to you and the appliance is reduced. In the event that you don’t have the needed skill, call a qualified electrician who is specialised in electrical house wiring and repair of various appliances.

I have shared with you how I do a voltage test using a multimeter.Do you have any questions?,experience using a multimeter.You are free you can leave a comment in the comments section below.

How to measure AC voltage with a multimeter.

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