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How To Determine Hot and Neutral Wire with Multimeter

Electrical outlets consist of several different wires. These wires carry the power from the distribution board to the outlet, and finally to the appliance we connect.

Since electronic gadgets play a vital role in our daily life, if any of the electric cablings goes bad in between the distribution board and the outlet, it becomes a hassle to get it fixed. As there are two types of wires inside any standard electrical outlet, namely the hot wire and the neutral wire.

Identifying them can be an issue if someone is not familiar with them. The best solution would be to replace any faulty wire, to get better service from any power outlet.

But doing so requires some knowledge before digging into the problem. Working with the wrong wire can lead to further damage or even become hazardous for the user.

To solve this problem, we can use a multimeter as a simple tool to identify the neutral and hot wire. This article explains the meaning of hot and neutral wire, the difference between them, and how to use a multimeter to identify them.

Simple instructions are provided so that the job can be done by someone who does not have much technical knowledge.

What is a Multimeter?

A multimeter is an electrical device, widely used to measure electrical voltage, current, and resistance. It is also used to test different electronic components and continuity in any electrical circuit.

A multimeter is a simple instrument that has several applications for engineers, students, and technicians in any engineering workshop or laboratory. This instrument is used mainly to measure the electrical properties of any material.

It can be used to measure voltage, current, and resistance, along with many other measurement functionalities. There are mainly two types of multimeters available, Digital and Analog.

While analog multimeters are becoming old due to a lack of testing capabilities and ranges, digital ones are becoming very popular. Digital multimers are also available in two subcategories: clamp-on multimeter and auto-ranging multimeter.

The price of a multimeter depends on the functionality and ranges of quantities it can measure. A very simple one would cost around $10-$40, which is adequate to test and measure for household purposes.

A commonly used multimeter comes with two probes, colored in red and black. The black probe is to be connected to the ground and the red probe is used to contact different points of any circuit to measure different values.

How To Determine Hot and Neutral Wire with Multimeter

How to Determine Hot Wire with Multimeter

As mentioned earlier, any electrical outlet has one or more hot wires, which supply power to the appliances connected to the outlet. Since this wire is always carrying current, it is dangerous to get in contact with it.

Most of the appliances we use have their wires covered in black PVC sheathing, which protects the hot wire from getting exposed. But inside this PVC sheathing, the wires are colored to distinguish between them.

A typical 3 pin plug has three colored wires, namely white, green and black (for the USA only). Whereas different parts of the world follow different color codes.

Here, black wire is the one carrying electricity when connected. So this is the hot wire and the white and green wires are the neutral and ground wire respectively.

In case the colors of the wires in an outlet are mismatched or not followed properly, then it creates a lot of trouble. This is where a multimeter comes in handy. It can be used to determine the wire that carries power. The steps given below can be followed to get the job done:

Step 1: Before going any further ahead, it is important to protect the user from electric shocks. So proper protection must be used. Rubber gloves and boots must be worn to avoid electrocution.

Step 2: The multimeter must be set up as per requirement. If it has a dial, then it must be rotated and set to 200VAC (or any higher value than the outlet can deliver). Usually, line voltages are 120VAC in the US.

Step 3: The black probe (or the common probe) must be connected to the ground wire of the outlet. The red probe can now be connected to any other wire to test for voltages. The probes must be connected firmly, to avoid loose connections and sparks.

Step 4: The reading on the multimeter can now be noted and the corresponding wire can be labeled as hot or neutral. If any wire has a value around 120VAC then it is a hot wire.

How to Determine Neutral Wire with Multimeter

Neutrals wires act as a return path for power flow in any circuit. They can be identified following the same steps mentioned above for hot wires.

The only difference is that a neutral wire would read 0V on the multimeter, as they don’t carry any electric current. But proper protection must be taken before touching any electrical wire.

How to Determine Ground Wire with Multimeter

Ground wires are provided for safety purposes. In case of a short circuit, all power must flow to the ground to keep the appliances and their users safe.

This is where the ground wire is utilized. Ground wires are color-coded to easily identify them. But color code can be mismatched or not followed as mentioned previously.

It becomes important to ensure the identification of the ground wire, for the sake of safety. The job is easy compared to neutral and hot wire, as ground wires are not provided in all outlets.

Outlets with a 3-wire connection contain hot, neutral, and ground wires, whereas two wired outlets only consist of hot and neutral wires.  Still, then it would be wise to know if the earth wire is connected properly.

The steps to determine a ground wire are:

Step 1: Ensure proper protection before testing any electrical wire.

Step 2: Set the multimeter dial to an ac voltage range higher than the voltage provided by the outlet.

Step 3: Connect the black probe to the wire to be tested (possible ground wire) and the red probe to the neutral wire.

Step 4: Check the reading on the meter. The meter should read 2-4 volts.  Although a ground wire should read 0V when tested with a multimeter, it is not seen when practically tested.

Step 5 (optional): Connect the red probe to the hot wire, keeping the black probe connected to the ground wire. The reading on the multimeter should be more or less the same as the reading found while checking a hot wire.

If the readings are different then the ground wire connection is poor.

Distinction Between a Neutral Wire and a Hot Wire

Wires in an outlet or a distribution box may be colored if the standards were followed while wiring the house. But it does not necessarily mean that the wire colors can be trusted with eyes closed.

A simple mismatch of color can cause severe damage to any electrical equipment connected to the outlet. Such occasions can be avoided if the wires are double-checked with color coding and voltage readings.

To put things simply, a hot wire, a neutral wire, and a ground wire are colored black, green, and white respectively. While the voltage between hot to neutral and hot to ground wire is around 120VAC, the voltage between the ground wire and neutral wire is slightly higher than 0VAC.

Precautions

Working with the ac mains voltage is a risky process. Also, while working with any tools, precautions are necessary to ensure the safety of the equipment and the user.

A professional always ensure safety precautions before starting a job. Below are some precautions that must be followed in order to avoid damage and risk to the user:

1) Always use a pair of rubber gloves when handling electrical wires. Touching any live wire with bare hands can be fatal. Even if the user survives the electric shock there is the possibility of amputation due to electrical injury.

2) A pair of goggles must be used while working with electricity. Electric cables and contact points can create sparks and flashes. This can be dangerous to the human eye when working at tight corners as the sparks are too close to the eye. Eye protection must be worn in such cases.

3) While working with a multimeter, one should always keep his or her hands on the insulated parts of the multimeter, rather than any metal parts such as the pointers on the probes.

4) Read the owner’s manual of the multimeter, before connecting it to any power supply. Connecting the probes to a supply higher than the multimeter can measure may damage the equipment.

The probes must be checked if they are properly connected for measuring voltage or current. Improper connection for any measurement may produce short circuits and sparks.

5) When working on any electrical outlet, it is wise to cut off the power supply by using the associated circuit breaker. This reduces the chances of short circuits and shocks in case of any error.

6) If a wire is found worn out, it should be replaced immediately rather than connecting them using electrical tapes.

 

Frequently Asked Questions (FAQs

1) Can a neutral and hot be wired together?

A neutral wire acts as a return path in any electrical circuit while the hot wire carries power to the circuit. If these two wires are connected together then it would create a short circuit.

An enormous amount of current would flow and burn the wires if they are not protected by a fuse or circuit breaker. Any user might get electrocuted if he or she tries to wire these two wires together.

Therefore, the neutral and hot wires should never be wired together.

2) If the neutral isn’t grounded, what happens?

Neutral wires are taken care of at the distribution end of the power provider company. In case there is a break in the neutral line it creates a floating point.

This results in improper voltages at the customer end as there is no return path available. Users may get mild or dangerous electric shocks if they touch any electrical appliances.

3) Why do we have more than one hot wire in an outlet?

Electrical outlets are directly fed from the distribution box. There might be more than one hot wire present at any outlet, as the homeowner might create more outlets in the future.

Unused hot wires can be connected together making a pigtail and capped off with a plastic wire nut.

4) Can a ground wire be used in place of a neutral wire?

Theoretically both ground and neutral wire don’t carry any power. But if they are interchanged then the grounding function is no longer available.

Also, replacing the ground wire in place of neutral wire will create a possibility of electric shock when exposed metal parts such as the frame of any appliance are touched. Rather the ground wire is provided to discharge any accumulated charge on the metal surfaces of any appliance.

5) Can you get electrocuted from the neutral wire?

As per the name, the neutral wire must not carry any power to the device. But if there is a broken neutral point from outside the house, then there is a probability of voltage being present on the neutral wire.

This means there is no chance of electrocution from neutral wire theoretically, but electric power systems can be uncertain at times.

6) Can a circuit function without a neutral?

Any electrical device needs a minimum of two wires to power it. The hot wire carries the power and the neutral acts as the return path.

Without the neutral the power cannot flow back to its original point; thus, electricity will not flow in the circuit. This means a circuit cannot function without neutral.

Final Thoughts

Working with electrical wires can be dangerous if we rely on their color only. One mistake can cause severe damage to the person or any electrical appliance.

Homeowners need to be careful while doing any electrical wiring job inside the house so that they or their equipment are not harmed.

Multimeters are cheap and easy to use to find solutions to different problems related to electric circuits. Getting a multimeter increases the chances of working on more devices and getting the job done, without spending much money by hiring a professional to do it.

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