How to use a multimeter to test voltage of live wires- A Complete Guide

Voltage is an important aspect of electrical systems, and it's crucial to ensure that the voltage is correct in order to avoid dangerous and costly problems. In this guide, I'll walk you through how to use a multimeter to test voltage of live wires. I'll cover everything from choosing the right multimeter for the job to taking to testing voltage with accurate readings. Let's get started!

An Introduction to Multimeters and How They are Used?

A multimeter is an electronic tool used to measure voltage, current, capacitance frequency and resistance. You can also test diodes and check continuity of any circuit. There are many different types of multimeters on the market, but all share the same basic functionality. The point where advanced multimeters differ is the accuracy and some additional features. You can use a multimeter for both home repairs and commercial applications.

When choosing a multimeter, it's important to consider the range of readings that the meter can take. The most common ranges are volts, amps and ohms. You should also consider the meter's accuracy and the type of probes that come with it.

Why is it important to test voltage of live wires?

It is important to check voltage in live wires because an incorrect voltage can cause problems with the electrical system. For example, if the voltage is too high, it can damage electronic equipment. If the voltage is too low, it can prevent devices from working properly.

Moreover, it can also be dangerous to work on live circuits without verifying the voltage first. If you accidentally touch a live wire, you could be shocked or even killed.

Tools Required for voltage testing:

  • Multimeter
  • Voltage tester
  • Wire strippers
  • Pliers


Best Multimeters for accurate voltage measurement

For accurate voltage measurements you need the best multimeter that comes with a variety of features, like NCV modes, non linear load measurement LoZ mode, True RMS and Auto ranging features. Keeping in mind this, I have made a list of 10 best multimeters for home and professional use. No matter if you want to measure AC voltage or DC voltage these multimeters can do both.

How to measure voltages live wire? 

If you don't know how to use a multimeter to test voltage of live wires then don't worry here i will guide you in 7 easy steps.

Step by Step Guide

Now that you understand the basics of voltage and multimeters, let's walk through how to test voltage with a digital multimeter. I'll be using a DMM in these instructions, but the steps are similar for other types of meters.

Step One: Choose the Right Multimeter

The first step is to choose the right multimeter for the job. The meter should have a voltage range that covers the voltage you are testing. It's also important to consider the accuracy of the meter and whether it has any special features, such as capacitance or frequency measurement.

Step Two: Set the Meter to Measure Voltage

Once you have selected the right multimeter, set it to measure volts. This is usually done by selecting the V-ohm-meter setting or the voltage symbol. If you are not sure how to do this, consult your meter's manual.

Step Three: Connect the probes.

Next, connect the probes to the meter. The probes typically have banana jacks on them, which can be attached to the leads of the electrical wire you are testing. Make sure that the jacks are firmly attached to the multimeter.

Step Four: Turn On The Meter

Once the probes are connected, turn on the meter by pressing the power button. Some meters have a selector switch instead of a power button. If your meter doesn't have a power button, you may need to plug it into an outlet. Always turn the meter on and select voltage ranges before connecting test leads to the circuit.

Step Five: Measure the Voltage

Now that the meter is on, place the probes across the two points in the circuit you want to measure. The voltage will be displayed on the screen. Make sure to take note of which probe is positive and which is negative, as this can affect the reading. You can connect the red test lead to the phase of an AC circuit and the black test lead to neutral wire, ground wire, or earth wire. But the most appropriate way is to use neutral wires. If you have an auto ranging multimeter then just set the multimeter knob to voltages(V).

Step Six: Compare the Reading to the Voltage Rating

Once you have taken a reading, compare it to the voltage rating of the wire. The rating can be found on the wiring diagram or on a label attached to the wire. If the reading is within tolerance, then you are good to go. If not, you may need to adjust the voltage with a transformer or some other device.

Step Seven: Record the Reading

Finally, record the reading in your work log or on another piece of paper. This will help you track any changes in voltage and ensure that your repairs are safe. If you want to know how to measure current (amps) in a circuit, I have also made a sperate guide about that.

How to measure voltage in neutral wire?

Now you know how to measure voltages in live wires for neutral wire you have to follow the same above mentioned guide. 

Safety Guide

safety-guide-while-checking-voltage-with-multimeter

Precautions while measuring voltages in live wires

There are a few precautions you should take while measuring voltage in live wires:

  • Always make sure that the meter is turned off before connecting the probes. After making connections you can energize the circuit.
  • Do not touch the probes to any other part of the circuit or exposed wires except for the two points you are testing.
  • Make sure that the probes are making good contact with the wire of the electrical and electronic devices you’re testing.
  • Do not exceed the voltage rating of the wire.
  • Record all readings in your work log. This will help you track any changes in voltage and ensure that your repairs are safe.

Now that you know how to use a multimeter to test voltage, you can safely work on live circuits. Just be sure to follow the safety precautions and you'll be good to go.

Conclusion

Now that you know how to use a multimeter to test voltage in live wires, you can safely work on electrical systems and repairs. Always be sure to check the voltage before beginning any work and use caution when working with live wires. You can also use a non-contact voltage tester to check voltage in live wires. Voltage testers are just like multimeters, I have also made a comparison of voltage testers and multimeters.

Remember, an incorrect voltage can cause problems with the electrical system and be dangerous. Make sure to take electrical value of voltages in multiple places to get a complete picture of the circuit's voltage.

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