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In 120 VAC circuits, the neutral wire carries all the return current from the hot wire. In a single phase 120 VAC circuit, such as found in US homes, the neutral wire carries exactly the same amount of current as the hot wire (unless there is a fault in the device). The difference is that the neutral wire is connected to the ground bus in the load center (also called "breaker box" in the Southern US).
In a three phase circuit, as was pointed out by another person, the neutral wire will carry any current that results from an imbalance in the phases. If the three phases are perfectly balanced, for example when connected to a motor, there will be no current in the neutral conductor. (In fact, in a three phase delta connection, there is no neutral. But I will not attempt to explain that here, beyond simply mentioning it.)
Nevertheless, anything that causes an imbalance in the phases of a three phase system will cause neutral current to flow. The amount of neutral current in a three phase system may be calculated using the phase relationships of the three phases, provided the imbalance is known, or simply measured with a standard AC current meter. (However, I must qualify this by saying that three phase systems are complex and hard to understand. It is easy to be fooled when working with such a system, and I would not undertake it without a thorough review of the principles involved. They do not behave in a simple and obvious manner.) However, I do believe that the neutral wire in a three phase system is often much smaller than any of the phase wires, because it is not called upon to carry the full current, but only the relatively small currents resulting from load imbalances.
In a 240 VAC system, such as is used to supply power for an AC unit in the US, again typically the neutral will not carry current unless there is some sort of problem. Rather, the current flows in the two hot wires. As before, the neutral wire is connected to ground at the load center, and is usually connected to the metal chassis of the device being powered, whether it be an air conditioning system, electric range, or hot water heater. This is to provide safety for the user, and also will help to trip the breaker if there is an insulation breakdown within the device.
Modern 120 VAC systems in the US have three wires. A safety ground wire has been added, and this is always connected to the metal chassis, except in certain devices that have extra insulation, such as power drills and most lamps. This ground wire is only for safety purposes, and normally does not carry any current. While the neutral wire is also connected to ground at the load center, it is a current carrying wire in a 120 V system, so is not usable for grounding the chassis as in the 240 VAC system. However, if there is an insulation breakdown problem in the device, the safety ground will conduct current and trip the breaker at the load center.
Interestingly, the fact that the neutral carries the same current as the hot wire in a 120 VAC system is used as the operating principle for Ground Fault Detectors. An electronic circuit in the GFD device compares the current in the hot and neutral wires. If they are not equal, the device trips a relay, removing power from the device. If the hot and neutral currents are not equal, this indicates an insulation breakdown, where some of the current is leaking to an improper place within the device. The Ground Fault circuit detects this and shuts down the device very quickly, preventing electric shock and potential loss of life.
What else can I help you with?
Why does electric current flow into circuits?
It may not be correct to say that an electric current will "flow into" circuits. Electrons move in a circuit in response to an applied voltage. And these electrons are alread in the circuit and available to support current flow if a voltage is applied. It may be more correct to say that electrons leave the negative terminal of a voltage source, and electrons enter the positive terminal of that voltage source. The electrons in the circuit that are availble to support current flow will "shift over" to create the current flow. Remember that the phenomenon of current flow in a wire is the "shifting over" of electrons in the wire. It's not about electrons going into one end of a wire and those same electrons coming out the other end. Use the link to the related question for more information that might help make things clearer.
What is difference between induced voltage and induced current?
Just as a current flowing through a wire will produce a magnetic field, so a wire moving through a magnetic field will have a current flowing through it. This is called electromagnetic induction and the current in the wire is called induced current. A stationary wire in the presence of a changing magnetic field also has an induced current. A changing magnetic field can be produced either by moving a magnet near to the stationary wire or by using alternating current. A stationary wire in a magnetic field which is not changing will have no current induced in it. You will sometimes see this effect described as induced voltage. Strictly speaking, you will only get an induced current in the wire if it is part of a complete circuit. A wire which is unconnected at both ends will have a difference in voltage between the ends (a potential difference) but current can only flow when the wire is in a circuit. Induced current is used in electricity generation and transformers.Another AnswerThere is no such thing as an 'induced current', only an 'induced voltage'. Current will flow only if the conductor into which the voltage is induced forms part of a closed circuit.
Can you get shocked and the electricity come out of your tongue?
Not usually unless you go around licking grounded objects when you are touching live electrical circuits. The only time that you will receive a shock is when you become the ground return for the electricity to flow through. In effect you become the neutral wire that returns the current flow that is supposed to go back to the distribution panel.
What is current and ammeters?
Current is the amount of electrons flowing. An ammeter reads this value. Typically an ammeter will be placed in series to measure this flow; there are also "clamp on" ammeters that use a small CT. When placed around a wire, the power flowing in the wire will induce a current in the CT, allowing measuremnt without lifting wires.
What does electromagnetism have to do with galvanometer?
A galvanometer is a simple meter that detects the flow of current. A current flowing in a wire causes magnetism around the wire. This is called electromagnetism. Like poles of a magnet repel and opposites attract. The Galvanometer uses these principles in order to move a pointer across a scale.
What will happen without a neutral wire?
Current needs a return path to earth to flow. The neutral carries this flow. Therefore, no neutral and no current flow.
Can a wire carry a current and still maintain a neutral charge?
No, a wire carrying a current cannot maintain a neutral charge. When a wire carries a current, it means that there is a flow of charged particles (usually electrons) through the wire, which results in a net charge within the wire.
When phase and neutral are glowing what is the problem in circuit?
There is more current flowing and the wire can not flow that much current.
Why neutral wire does not carry current in closed ac circuit?
The neutral wire does carry current in a closed AC circuit. Clamp a clamp on amp meter around the neutral wire directly after the circuit load and it will read the same current as is on the "hot" wire.
Is there any current flow through the neutral wire of single phase motor?
Yes. It is identical to the line current.
What is the purpose of the neutral wire in an electrical circuit?
The purpose of the neutral wire in an electrical circuit is to provide a return path for the current to flow back to the power source, completing the circuit and ensuring a balanced flow of electricity.
What is the function of a neutral wire in an electrical circuit?
The function of a neutral wire in an electrical circuit is to provide a return path for the current to flow back to the power source, completing the circuit and ensuring a balanced flow of electricity.
What is the neutral wire used for in electrical circuits?
The neutral wire in electrical circuits is used to complete the circuit and provide a return path for the current to flow back to the power source. It carries the current back to the electrical panel to ensure a balanced flow of electricity and to prevent electrical hazards.
Is a neutral wire in a 4 wire service?
Yes, in a 4-wire electrical service, the neutral wire is included along with the hot wires and ground wire. The neutral wire is used to complete the circuit and provides a return path for the current to flow back to the source.
Does a neutral wire carry current in an electrical circuit?
Yes, a neutral wire carries current in an electrical circuit.
What is the flow of current through a wire known as?
The flow of current through a wire is known as electrical current.
Which wire in a cable is at or near to 0V and conducts an electric current whenever the appliance is switched on?
The wire that is at or near 0V and conducts an electric current whenever the appliance is switched on is the neutral wire. This wire completes the circuit and provides a return path for the current to flow back to the source.
