A multimeter can help you obtain a lot of information about your electric stuff. Want to check a power outlet and see if it's got the right voltage? The multimeter is the tool you need.

What Is Voltage?

Voltage is the potential difference between two points in a circuit. Named after the Italian physicist, Alessandro Volta, voltage is measured in volts. When you have a 1.5V battery, it means that the potential difference between the two terminals in the battery is 1.5 volts.

Since voltage is the difference in potential by definition, it is always measured for two points. Basically, it's impossible to measure the potential for a single point on a circuit but you can easily measure the difference between the potentials of two points.

an electronic circuit board.

Types of Voltage

Voltage is either AC voltage or DC voltage. AC stands for Alternating Current and DC stands for Direct Current. While alternative currents flow in sine waves, direct currents travel in a straight line and in one direction only. You can read our guide on AC and DC to understand the difference between the two more clearly.

What Is a Multimeter?

A multimeter is a tool that measures a multitude of electrical properties such as current, voltage, and resistance. Multimeters vary in appearances and they may also have different secondary functions, but their main purpose is the same.

All multimeters measure current, voltage, and resistance. Some more advanced ones can measure frequency, temperature, and other properties as well.

Regardless of it being digital or analog, a multimeter consists of a body and two probes. One end of either probe plugs into a slot on the multimeter, and the other end connects to the circuit you want to measure.

Related: Easy and Low Budget DIY Electronics Projects for Beginners

How to Check 220V Voltage With a Multimeter?

One of the usages of a multimeter is to measure the potential difference or voltage of an electronic circuit. In this article, we're going to measure the voltage of a standard 220V power outlet using a digital multimeter.

1. Plug In the Probes

Multimeters come with two probes, one red and one black. Every multimeter has at least three slots. One of the slots is COM or the common slot, where the black probe is plugged into. This slot is usually situated in the middle.

The next slot is for voltage, resistance, and usually low currents. This means that if you want to measure any of these properties, you have to plug the red probe into this slot. To measure AC voltage, this is the slot we're going to use.

The third slot is for scenarios where you want to measure high currents. This usually means currents higher than 400mA and less than 10A. Though the definition of high current depends on your multimeter, so pay attention to its inscriptions.

The multimeter pictured below has a fourth slot for very low currents and temperature.

A typical multimeter and its ports

Since you're going to measure voltage here, then you should plug the probes in the COM slot and the voltage slot.

  1. Plug the black probe into the COM slot.
  2. Plug the red probe into the voltage/resistance slot.

The red and black leads aren't structurally different and the color difference is meant as a convention. As a general code among all multimeter manufacturers, black means negative and red means positive.

2. Turn On Your Multimeter

The next step is to turn on the multimeter. To do this, simply find the power button on your multimeter and turn it on.

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3. Switch the Knob and Set It to Voltage

Your multimeter has a knob on it that allows you to select what you want to measure. This gives the multimeter a heads-up on what to expect and allows it to show the relevant information. To measure the voltage of a power outlet:

  • Switch the knob and put it in V. The V with a ~ symbol on top means AC voltage, while the V with a ⎓ symbol means DC voltage. The voltage in your power outlets is alternative current so you should put the knob in AC voltage.
  • If there are different ranges of voltage on your multimeter, then put the knob in the range you expect. We're expecting something around 220V for the power outlet.
  • If you don't have an estimate of the voltage you might get, then put the knob in the highest range so you can work your way down for an accurate result.

Like the one in the picture below, some multimeters can measure both AC and DC voltage with the same setting. These multimeters have a specific button that allows you to switch between AC and DC voltage.

A multimeter knob on voltage.

4. Connect Probe Leads to the Power Outlet

Now everything on the multimeter is set and you're ready to measure the voltage. Let's check it out and see if the power outlet really is 220V. Unlike DC voltage, AC voltage doesn't have polarity so it doesn't particularly matter which opening you stick the probe leads in.

  1. Insert the black probe lead into one of the openings on the power outlet.
  2. Insert the red probe lead into the other opening on the power outlet. Note that the order is important as a safety measure. Always connect the black probe lead first.
  3. Read and record the voltage from the multimeter.

Always handle the probe leads with their plastic covering! Once the leads are connected to the outlet they'll have 220V live electricity going through them and touching them can be fatal.

A multimeter showing the voltage of a power outlet.

Connecting the red and black leads to opposite openings doesn't affect the value you're going to get. However, if you were measuring DC voltage, swapping the nodes would give you a negative value, though the number would still be the same.

5. Disconnect the Probe Leads From the Power Outlet

Once you've recorded the voltage, it's time to disconnect the probes from the power outlet. You should do this in reverse order.

  1. Disconnect the red probe lead from the outlet.
  2. Disconnect the black probe lead from the outlet.
  3. Turn off your multimeter.
  4. Disconnect both probes from the multimeter.

Now You Can Measure Voltage

A multimeter is an amazing tool capable of giving you lots of information on your electric and electronic assets. Now you know how to use it to check 220V voltage and can use it to measure the voltage for plenty of other things too. If you measured a battery's voltage and it was dead, don't throw it away! There's still plenty you can do with it.