How to Use a Multimeter to Test Voltage of Live Wires?

How to Use a Multimeter to Test Voltage of Live Wires?

A multimeter is a device that can measure and monitor electric currents, voltage, resistance and other electrical values.

Benefits of using a multimeter:

  • Can test voltage of live wires;
  • Can help identify electrical problems;
  • Helps ensure safety while working with electricity;

When working with electricity, it is important to know how to use a multimeter to test the voltage of live wires. This device can help identify electrical problems and ensure safety while working with electricity. It is also a valuable tool for troubleshooting purposes.

It is no secret that electricity can be dangerous, but it doesn’t have to be. For example, if you are using a multimeter to measure the voltage of live wires, then you will need to know how to use one safely. Many people don’t realize that there are different types of wire and that each type requires its own set of safety procedures. This blog post will teach you all about measuring voltage with a multimeter!

A Live Wire: The Definition

A Live Wire: The Definition

An electrical wire through which there is a flow of electrical current is called a live wire. Unlike a live wire, the neutral wire has no potential – this distinguishes it from the neutral wire due to the voltage potential. A simple example is the operation of household appliances utilizing current fed into them by an active wire, whereas the neutral wire returns the current. Live wires have often been observed to have the highest voltages, and if you touch them directly, they can be deadly [1].

Electron Bot Quote

In my estimation, understanding the distinction between live and neutral wires is crucial for electrical safety. Live wires carry potentially deadly voltage, supplying power to appliances. The neutral wire completes the circuit, ensuring current returns safely. Proper awareness and precautions are vital when dealing with live wires to prevent accidents and ensure electrical safety.

Jesse Rodriguez, Embedded Systems Developer, Greensboro

Live wires are very common in our daily life. Wires that deliver electricity to houses and buildings from the power supply or a generator is known as a live wire, whereas those carrying current for lighting within the building walls are called “neutral” wires (which do not have high voltage). The number of active/live wires used depends upon the quantity of electrical wiring being supplied by them, thus making it necessary to have sufficient feeders with adequate capacity for their transmission.

What is a Multimeter?

A multimeter is a tool that may be used to measure electric current, voltage, and resistance across a variety of ranges. It’s a useful yet adaptable gadget that comes in handy for measuring electricity at any time. It is a purpose-built electronic gadget with the ability to measure Voltage, Ampere & Ohms in wires. As a result, it is also known as a multi-tester or VOM (Volt-Ohm-Meter) [2].

The multimeter has a number of terminals that can be attached with some wires. The voltage and current will pass through the wire, while they are being measured by the tester. A movable scale indicates different values under which it is connected to test its conductivity.

What is a Multimeter?

Multimeters are used to:

  • Measure live electrical wiring at homes or offices for several reasons including repairing electrical equipment like air conditioners/refrigerators, etc.;
  • Check if there’s any internal malfunction in devices because of power shortage;
  • Test electric circuits using a fuse tester/circuit breaker tester;
  • Find out faulty circuit boards & components within electronic devices (like computers);
  • Detect heating appliances or tube lights having insufficient wattage causing frequent breakdowns often due to overloading the circuits, and many more;

Why is it Important to Check the Voltage of a Live Wire:

1) To ensure the power supply works perfectly

When an electronic device starts to behave abnormally, the first thing that needs to be checked is the voltage of a live wire. This will help diagnose whether the problem is due to low or high voltage and take corrective action.

For instance, if you are using a laptop and it keeps shutting down suddenly, you can check the live wire’s voltage with a multimeter and see if it falls within the acceptable range. If not, then you know that you need to increase the power supply or change some other component in order for your device to work properly again.

2) To prevent hazard/electric shock/injury

High voltage can be dangerous and may cause electrocution or fire. Heavy metals like copper or aluminum have the potential to conduct large amounts of electricity that is why they are used in power lines & electrical equipment. If you touch a live wire with your bare hands, a high current will pass through them causing serious injury or worse leading to fatality.

To prevent hazard/electric shock/injury

Wires that deliver electricity from one place to another need not necessarily be touching any other wires & objects for their voltages/currents to flow properly (with some exceptions). A multimeter measures these parameters at set points. Therefore, it’s important that you test every component associated with such components before connecting them together because this avoids accidents later on due to voltage differences.

3) To fix a problem

If you find that the voltage of a live wire is too high or low, then it’s important to take corrective action and fix the problem as soon as possible. A multimeter can help identify where exactly the issue is and what needs to be done in order to rectify it. For example, if the voltage is too high, then you might need to install a circuit breaker or replace some components in your electrical system.

On the other hand, if the voltage is insufficient then you might need to upgrade your power supply or add an extra fuse box.

Electron Bot Quote

Personally, using a multimeter to measure live wire voltage is a crucial safety practice. It enables the identification of potential issues, allowing for timely corrective measures. Whether adjusting circuit breakers or upgrading power supplies, maintaining the right voltage is essential for safety and preventing electrical hazards. Consulting an electrician for assistance is advisable for those unfamiliar with multimeter use.

Ryan Cooper, Electrical Technician, Henderson

Using a multimeter to measure the voltage of live wires is an essential step for ensuring safety and preventing any hazardous situations from arising due to electricity. It also helps in diagnosing and fixing any electrical problems that might be present in your system. So, if you are not sure how to use a multimeter or are hesitant about doing it yourself, then please call an electrician for help. They will be more than happy to assist you.

To fix a problem

If the voltage of a live wire is insufficient, it will produce heat while conducting current through high resistance wires or cause equipment damage like short circuits when connected to low/zero impedance wires (like power lines).

This could lead to malfunctioning devices and system shutdowns at times due to overheating. Therefore checking if your electrical supply has sufficient capacity & can meet rising demand is important for the smooth functioning of any appliances within the building.

How Should You Use a Multimeter:

1) Everything should be safe

In order to test the voltage of a live wire, unplug it from the outlet and place one probe of the multimeter on each wire’s end.

If there’s no reading, the wire may be dead or there could be something blocking the current like insulation. In either case, you’ll need to get an electrician in to take a closer look.

2) Select voltage (as the device parameter)

Place one probe of the multimeter on each end of the wire. If you’re getting a reading, write it down and then turn off the power to that circuit at the breaker box. Be sure to label which wire is which so that you can reconnect them correctly later.

If there’s no reading, make sure to check all your connections again. Or you may try clearing out any insulation from around wires.

You should see an alternating current signal between 0-0 VDC (if units are set up properly). The measured value will be flashing due now; this means that nothing has been measured.

Now select resistance and place one probe on each end of the live wire.

2) Select voltage (as the device parameter)

3) Connect the probes to the appropriate sockets

Connect probes to appropriate sockets on multimeter: red clamp goes with positive (+), black clamp goes with negative (-). The same color code is used in most digital multimeters but experts recommend that one double checks this because it can vary between models.

4) Putting the probes to work

Turn the multimeter on by hitting the power button. The meter should now be in volts mode. If it’s not, hit the V/Ω button to toggle between modes until you get a V reading on the screen.

Touch one probe to one end of the wire and touch the other probe to the other end of the wire. You should see a voltage reading onscreen. Write this number down!

Now measure resistance by touching one probe to each end of the live wire. No voltage should be shown onscreen; if there is, check all your connections again or clear out any insulation from around wires and use reasonable force if necessary until you get a response.

The multimeter will now show a value for resistance (in ohms) on the screen. Write this number down!

If you’re done testing, turn off the multimeter by hitting the power button. Disconnect probes from sockets and put away your meter.

Warning: never test voltage or current on a wire that’s connected to an appliance like a refrigerator or air conditioner. You could damage the equipment or worse, yourself! Only test wires that are unplugged from outlets.

Cautions of Checking the Voltage of Live Wire

When checking the voltage of live wires, we need to be cautious in a few situations. For example: when it is required to touch the metal part on which current flows and there are other conductors nearby that could lead away from danger, or if carrying out tests with no one present for assistance if something goes wrong, etc. In these cases, please use an insulated tool such as an insulating stick (insulation tester).

Read more guides to improve your understanding in electronics:


1. How do you check the voltage on a multimeter with a live wire?

Make certain the dial of your garage door opener’s meter is set to Volts AC. Insert one lead into one side of an electric socket and nothing happens, insert the other lead into the opposite side of the socket. The ground side of the socket will demonstrate a difference of 100 Volts AC while the hot side, which is connected to 110 volts AC, will display no variation. If you’re using 220 Volts AC, have a skilled person check it for you [3].

2. How to find out if the wire has life without a multimeter?

Attach a couple of wires to a socket and a light bulb, then touch one wire to the ground or neutral and the other wire to the test. If the lamp lights up, it’s live. Otherwise, check that the lamp is lighting on the live cable like a wall outlet to ensure that it does so [4].

3. How to check 240 voltage with a multimeter?

Use a multimeter to measure 240 volts. If you are working with 100-volt circuits and the current is greater than 15 amps, use an ammeter instead of a voltmeter.

A voltage meter can be used in different ways: AC (alternating current ) or DC (direct current). It’s important to remember which way it operates because if you accidentally connect it backward, the readings will not make sense since wrong connections convert direct into indirect voltages and vice versa.

The most common mistake when checking voltage on wires is that people do not check their equipment first before performing tests on live wires. For example, they should test whether their circuit tester works by using batteries without touching any electric cables until after doing so.

The power of the voltage meter should always be checked with a multimeter; if it is not working, it might blow out fuses and give an inaccurate reading.

In order for a voltage meter to read properly, both probes (metal tips at the end of the wires) must be inserted into the correct jacks – usually red for positive and black for negative. If they are reversed, then whatever value is displayed on the meter will be wrong.

When checking 220 volts AC, there are two ways to do so: with or without touching the metal part. To check without touching the metal part, use alligator clips on each probe wire instead of inserting them directly into the socket. This way you can hold onto insulated handles while getting an accurate reading [5].

4. How do you measure voltage in a live circuit?

You need to use caution when measuring voltage in a live circuit. When working with circuits that have currents over 15 amps, experts should use an ammeter instead of a voltmeter. It’s important to remember which way the meter operates because if you accidentally connect it backward, the readings will not make sense.

The probes must also be inserted into the correct jacks for the meter to read properly- usually red for positive and black for negative. If they are reversed, then whatever value is displayed on the meter will be the wrong measurement [6].

5. Can you get shocked using a multimeter?

Yes, you can get shocked using a multimeter if you’re not careful. Be sure to read the safety instructions that come with your multimeter, and always use caution when testing live wires. Also be sure to keep the probes of the multimeter away from each other while testing voltage, like this, could also create a dangerous shock.

6. How to test a ground wire with a multimeter?

To test a ground wire with a multimeter, first, make sure that the power is off. Touch one probe of the meter to the ground wire and touch the other probe to any metal part of the appliance. If there is continuity, the meter will read zero; if there is no continuity, it will read infinity.

7. Why is my multimeter not reading voltage?

There are several reasons why your multimeter might not be reading voltage. Be sure to check that the probes are inserted into the correct jacks, that the power is turned on, and that the meter is set to measure volts. If none of these things seem to be the problem, then it’s possible that there is a short in the wiring or that there is no voltage present in the circuit.

Useful Video: Testing bare wires for 110 volts vs. 220 volts (outlet vs. baseboard heater)