How to Identify Neutral Wire with a Multimeter (4-Step Guide)

If you’re an apprentice or do it yourself and trying electrical work you should know how to identify different types of electric wires – the live (a.k.a. hot), neutral, and ground wires. You can easily trace the cause of inconsistencies in your systems by recognizing the open neutral points and fixing them.

Some inexperienced electricians may mix up the wiring so you cannot always rely on color codes to tell a neutral wire from the other two wires.

So, how can you recognize a neutral wire if the wiring harness is jumbled up? Well, you need to use a multimeter or a tester. I have been an electrician for over a decade and today I will teach you how to use a multimeter to single out a neutral wire from any type of connection.

Quick summary: let’s use an outlet as an example. First, remove the plastic cover from the wall socket or outlet and pull all three wires out. next, strip the insulation coating of the wires to reveal about ½ inch of the naked wire. Set your multimeter to the voltage reading. Ground the black probe on a surface such as a fridge. Isolate the ground connection, and then touch the red probe lead to the terminals of the remaining two wires; one at a time. The wire that does not give a voltage reading is the neutral wire. The hot wire will give a voltage reading.

4-Step Guide to Recognizing a Neutral Wire with a Multimeter

It is a must to distinguish neutral, live, and ground wires in any electrical fixture before a repair. You cannot wire new electrical components like new bulbs and sockets in a fixture without knowing which wire is for what. So, the following steps will help you.

Step 1: Safety First

Safety is an integral aspect of any process that may cause severe or mild damage. The dangers of electricity – electrocution or shock, are well-known issues with wiring. So, always turn off the main power supply before you begin wiring. (1)

Step 2: Wall Outlet/Socket and the Multimeter

If your wall outlet has a plastic cover, use a screwdriver to remove the screws and the cover, and then bring out the three wires from the socket.

Now set your multimeter to the highest voltage reading. Since you will be dealing with alternating current, set the multimeter range to ac.

multimeter with 1666 reading

Step 3: Using the Black Probe

If the multimeter probe leads are not inserted in their respective ports, insert the correct end of the black probe into the socket labeled com. plug the red probe into the port with the v label.

testing wires with multimeter probe tip

Connect the black probe to a grounding surface such as a fridge, water pipe, or faucet. At this point, the multimeter should not display any value yet.

Step 4: Testing the Neutral Wire with the Red Probe

multimeter reading at 244v

Before testing the neutral wire, calibrate the multimeter by pinging the probes. You should hear a sharp beeping sound. Your multimeter is ready.

You can use a wire stripper to strip off the insulation of the three wires to about ½ inch if the terminals are not well-exposed.

Now touch the red probe lead to the stripped terminals of the three wires – while the black probe remains grounded. Now touch the probe on the remaining wires. If you get a voltage reading for any of the cables, that wire is hot or live. Of the two wires, the one that does not give a voltage reading is the neutral wire.

Precautions to Take When Testing a Neutral Wire

  1. Have your safety gear on, and use a probe. you should have your safety goggles and insulated gloves. The goggles will protect your eyes from flashes and sparks while the insulated gloves will curb electrocution in case you touch a live wire. You may also want to remove metallic objects from your pocket before you begin the process.
  2. Do not touch live surfaces That contain electrical charges while using a multimeter. Hold the insulated or rubber parts of the multimeter.
  3. Turn off the main power supply If you are new to wiring. It will be much safer to do so; working with a live circuit is dangerous for beginners.
  4. Avoid working with wet hands, or standing on wet surfaces When testing for a neutral wire.

Frequently Asked Questions – Faqs

How Can I Tell a Neutral Wire from The Ground and Live Wires?

wiring colour changes

The easiest way to pinpoint a neutral wire is to know the color code. Neutral wires are blue, live wires brown, and ground wires are green. The color codes may be different in your country, make sure you know them. (2)

However, that is not the best method to use to identify wires. Some electricians may decide to mix up the colors and that is unacceptable and dangerous. So, always use a multimeter test to check the wires to be safe.

You may also use a tester; hot wires have 220 or 230 volts whilst neutral wires have zero volts.

What is an Open Neutral Connection

Open neutral is a situation where two points lose the neutral wire link; hence there is no neutral connection between the two points. Open neutral points can disconnect the system or cause inconsistencies.

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References
(1) dangers of electricity – https://www.cdc.gov/disasters/electrical.html
(2) color codes – https://www.computerhope.com/htmcolor.htm

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.