What is Floating Neutral?

In an electrical system, there are three types of conductors used, they are phase, neutral, and ground. In general, the neutral wire is grounded for safety and stability reasons. But sometimes, a condition occurs where the neutral wire of the systems is disconnected from the ground terminal, this condition is known as floating neutral.

In some special situations, the neutral wire is intentionally left isolated from the ground terminal, this is also known as floating neutral. In this article, we will learn about floating neutral in electrical systems, its effects, causes, and methods of testing and fixing the floating neutral.

What is Floating Neutral in Electrical?

As we know, the neutral wire is one of the important components of an electrical circuit as it provides a return path for the flow of electric current from load back to the source and completes the circuit.

In practice, the neutral wire is connected to the ground for safe and stable operation of the electrical system. But, due to some mechanical, environmental, or several other factors, the neutral wire could be separated from the ground or sometimes it is intentionally left ungrounded. This condition where the neutral wire is isolated from the ground is referred to as floating neutral.

The following are some common causes due to which the floating neutral can occur in an electrical system −

• Loose connections

• Improper circuit connection

• Braking of the neutral wire

• Short circuit or overcurrent fault, etc.

The condition of floating neutral in an electrical system is depicted in the following figure.

In this figure, the floating neutral is occurred due to breakage of the neutral wire.

Effects of Floating Neutral

The following are some major problems and effects that can be introduced due to floating neutral in an electrical system −

• Floating neutral does not provide any direct connection to ground, due to this there is high risk of electrical shock in the case of fault conditions.

• Due to floating neutral, there can be voltage imbalances or stray currents in the circuit that can affect the operation of equipment or may damage it.

• In the case of floating neutral condition, it is quite difficult to detect faults in the system that can pose severe electrical safety issues.

• Since, due to floating neutral, we do not get a reference point to perform testing and voltage measurements.

Factors Causing Floating Neutral

Floating neutral in an electrical system can occur due to several factors. Some of the common factors that can cause the condition of floating neutral in an electrical system are listed here −

• One of the primary reason due to which floating neutral occurs is loose or damaged connections at electrical panels, outlets, or junction boxes. These issues break the proper connection of the neutral wire to ground terminal and results in a floating neutral.

• Floating neutral can be also caused due to incorrect wiring practices like improper connections of grounding systems.

• The operational problems related to electrical equipment like transformers, circuit breakers, etc. can also break the neutral-grounding path and cause a floating neutral condition in the system.

• Environmental issues like corrosion of electrodes or conductors can damage the neutral-to-ground connection and results in floating neutral.

• Floating neutral can also occur due to voltage transients caused by lightning strikes near the electrical systems, as they can damage the grounding system.

• Any kind of physical damage to the neutral wire can interrupt the connection between neutral and ground and causes floating neutral condition.

• The electrical components degrade over time. Hence, the breakage in neutral-ground connection can also occur and cause floating neutral condition in the system.

• Sometimes, floating neutral can occur due to human errors during installation and maintenance of the system.

Testing for Floating Neutral

In electrical systems, several diagnostic procedures are executed to test whether there is a floating neutral or not.

Some of the commonly used methods to test for floating neutral condition are listed below −

Visual Inspection − In this testing procedure, the electrical panels, outlets, and junction boxes are checked for any physical damage, lose or improper wiring connection.

Multimeter Inspection − In this method, the floating neutral condition is identified by using a multimeter. For this, the voltage is measured between the neutral wire and ground terminal for any voltage imbalance. There is no floating neutral, if this voltage is equal to or near zero volts. Any other higher value of voltage suggests a floating neutral condition in the system.

Testing for Ground Continuity − In this method, we check the continuity of the ground wire by using a multimeter in the continuity test mode. If the continuity reading is true, then it indicates a proper grounding and no floating neutral condition.

Methods of Fixing Floating Neutral

In most electrical systems, floating neutral is an undesirable condition. Thus, it needs to be identified and resolved as soon as possible. Some of the common practices to be followed to fix a floating neutral in an electrical system are explained below −

• First of all, perform a visual inspection of the electrical system components like panels, outlets, junction boxes, and circuit wiring to identify any physical damage, lose or improper connections.

• Tight the loose connections if any. Also, properly tight all terminal screws in panels, switches, and junction boxes to ensure proper electrical continuity.

• Check whether the grounding system is in good health and working properly.

• Check whether the connection between the neutral wire and the ground terminal is proper. If there is any damage or fault in the neutral to ground bond, repair it.

• Sometimes the floating neutral is caused due to improper functioning of electrical equipment connected in the system. So, in that case you have to repair or replace that faulty equipment as per need.

Once have performed the above-mentioned practices, again verify that the floating neutral condition is resolved. For this, you may use a multimeter to measure the voltage imbalances between ground and neutral.

Conclusion

From the above discussion, we can conclude that the floating neutral is an undesirable condition that poses issues related to safety and stabile operation of an electrical system. Therefore, to ensure stable and safe operation of an electrical system, it is important to perform regular maintenance and periodic inspection to prevent the problem of floating neutral and its effects in the system.

It is also important to note that floating neutral is sometime a desirable condition in some special electrical systems like portable generators, remote power systems used in marine applications, etc.

FAQs Related to Floating Neutral

In this section, we have answered some commonly asked questions related to the floating neutral in electrical.

1 − How do you identify a floating neutral?

We can identify a floating neutral condition in an electrical system by any of the following methods −

• Visually inspecting for any physical damage in the neutral to ground connection.

• By measuring the voltage between ground and neutral, if this value is not equal to or near zero volt, then it indicates a floating neutral condition.

2 − What is the difference between neutral and floating neutral?

In an electrical system, a neutral is a conductor that provides a return path for current flow from load back to the source and is typically connected to the ground point. On the other side, the floating neutral is a neutral wire which is isolated from the ground.

3 − How do you protect floating neutral?

As we know, the floating neutral is mostly an undesirable condition, hence we have to take some protective actions against it. Here are some common practices that we follow to protect electrical system against floating neutral −

• Provide a proper grounding system as per the industry standards.

• Perform regular inspection to check for physical damage, deterioration, loose or improper connections that can cause a floating neutral in the system.

• Test the neutral-to-ground connection periodically.

• Use fault detecting devices, ELCB, RCCB, GFCI, etc. to protect the circuit against faults.

• Use efficient surge protection equipment to provide protection against transient voltage surges caused due to lightening.

4 − What is floating neutral in 3 phase system?

In practical 3-phase systems, the neutral is connected to the ground and acts as the reference point for three phases. A condition occurs when the neutral wire of the system is electrically disconnected from the ground point and results in a floating neutral.

5 − What is an example of a floating neutral?

When the neutral wire of a generator is disconnected from the ground or earth, then it acts as a floating neutral.

6 − What can cause a floating neutral?

The floating neutral can be caused due to the following major reasons −

• Physical breakage of the neutral to ground connection.

• Equipment malfunctioning can also cause floating neutral.

• Environmental causes like corrosion of grounding conductor can cause floating neutral.

• Human errors in maintenance work can also result in floating neutral, etc.

7 − Is floating neutral safe?

No, a floating neutral in an electrical system can result in various electrical dangers like electric shock & fire, equipment damage, unstable system operation, and more.

8 − What is the impact of floating neutral in power distribution?

The floating neutral can cause the phase voltage to increase beyond the line voltage and can damage the consumer’s equipment connected to the system. It can also cause electrical safety issues like electric shock and fire.

9 − Why do inverters have floating neutral?

In the case of inverters, the floating neutral isolates the AC output from the ground potential. This helps in improving electrical safety and reducing the risk of electrical shock.