Home » Blog » Bonded Neutral VS Floating Neutral
Last Updated December 28, 2022
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Among all the generator’s specs, the type of neutral bonding could be one of the most enigmatic for a person who only has little understanding of electrical engineering.
You may have come across the terms “floating” and “bonded” neutral. While they sound obscure to many people, they are an important factor when hooking up your portable generator to a transfer switch.
But, before we go into the specifics of a bonded and floating neutral, we must first explain what a “neutral” is, and how it is different from a “live/hot wire” and a “ground”.
Difference Between Live/Hot, Neutral and Ground
An electrical circuit consists of two wires. One carries the current from a source to a load, and the other returns this current back to the source. In any electrical circuit, this loop must be closed for the current to flow.
A wire that carries a current from a source to a load is called a “live/hot wire” – a current carrying wire.
A wire that returns the current back to the source is called a “neutral wire”, or simply neutral – current carrying wire again.
Contrary to these two, a “ground wire”, or just ground, is not a part of the electrical loop and only carries current in a fault condition. The ground wire is basically a protective wire, whose purpose is to ensure the safety of the system.
Bonded Neutral Generator
In a bonded neutral generator, the neutral is bonded to the generator’s frame. The transfer switch, must in this case transfer the neutral to meet the safety standards according to NEC (National Electrical Code) article 250.
The safety standards of the NEC article 250 require that the neutral must be grounded at the first means of disconnect (which means the nearest possible point), and cannot be grounded twice, to avoid induced transient voltages or currents.
To elaborate, let’s take an example of a residential home circuit.We are interested in connecting a generator to a home circuit. First, we must learn how a residential electricity system works.
In residential homes, all load is powered by a utility (an electricity distribution company). The power cables from the utility are connected to the electrical panel installed in homes (diagram below). The electrical panel distributes this power to each circuit within a home.
Load connected to the home electrical panel
The electrical panel (also called distribution board) is a system that distributes current to different circuits within a home or a building. It contains separate fuses or circuit breakers for each circuit, often enclosed in a metal enclosure. All the neutral points are grounded at a single common point.
To shift the load from the home electrical panel to a generator, a transfer switch is used. The transfer switch always transfers (disconnects from the home electrical panel and connects to the generator’s terminal) the live/hot wire. So, only the neutral wire stays in question.
As per NEC standards, we cannot ground the neutral twice. Since the generator already contains a neutral bonded to the ground, the transfer switch must transfer the neutral from the home electrical panel to the generator’s neutral terminal (diagram below).
Load connected to the bonded neutral generator
We can observe that the load is completely isolated from the home electrical panel and is mounted directly onto the generator. Thus, a bonded neutral generator behaves as an isolated or a stand-alone unit.
Floating Neutral
In a floating neutral generator, the neutral is not bonded to the generator’s frame. Therefore, the ground must be provided by the home panel. The transfer switch, in this case, does not transfer the neutral to comply with the NEC standards.
The load is transferred from the home electrical panel to the floating neutral generator in accordance to NEC article 250. As per the standard, neutral must be grounded once, and not more than once. However, the generator does not have a grounded neutral.
Load connected to the home electrical panel
Therefore, the transfer switch does not transfer the neutral. It only connects the load to the generator’s neutral. The neutral from the generator is now connected to the load and is grounded via the home electrical panel (diagram below).
Load connected to the floating neutral generator
In a floating neutral generator, since the neutral is not bonded to the generator’s frame, both wires are normally current carrying wires. Therefore, both slots of the receptacles on the generator are considered live/hot receptacles.
If there is a short circuit between any slot of the receptacles and the generator’s frame, the return path, i.e. neutral wire, is not bonded to the frame. There will be no return path for the current to flow through. Therefore, all the short circuit current will flow through the metal frame into the ground and thus, providing safety from the short circuit current.
Floating neutral generators are used for systems which already have a grounded neutral, e.g. home electrical panels, some recreational vehicles etc. The generator is connected by means of a transfer switch that does not transfer the neutral.
There are no standards for a specific type of generator to have a bonded or a floating neutral.
Summary of Differences Between Bonded and Floating Neutral Generators
| Bonded Neutral Generators | Floating Neutral Generators |
|---|---|
| Neutral is bonded to the frame. | Neutral is not bonded to the frame. |
| Transfer switch transfers the neutral. | Transfer switch does not transfer the neutral. |
| Protects from transient voltages. | Protects from short circuit. |
| Mostly used in stand-by and open frame generators. | Widely spread in portable inverter generators. |
| Can be used both as an isolated unit and for systems with a grounded neutral. | Used for systems with a grounded neutral. |
How to check for Floating Neutral or Bonded Neutral?
As a standard practice, the type of neutral, bonded or floating, is usually clearly mentioned near the portable generator’s outlets.
The slots of a NEMA 5-20R receptacle
Another simple way to check for the type of neutral bonding is to consult the generator’s manual or visit its manufacturer’s website. You can also call the manufacturer and inquire directly.
The type of neutral bonding can also be detected using a continuity tester. For this, first, turn the unit off. Now insert one lead of a continuity tester in the neutral slot of any AC receptacle (you can consult the user manual to find it) and attach the other lead to its metal frame. Continuity means that the neutral is bonded, and in case of discontinuity, it is floating.
Wrapping Up
The electromechanics behind bonded neutral generators are in a stark contrast to floating neutral generators. Hence, their respective applications may differ.
Therefore, we must first carefully determine the type of generator that we need before hooking it up. Any misjudgment can be very dangerous. However, it is worth noting that it is normally possible to convert the neutral.
You should never try to modify a generator on your own. It is not only dangerous but will also void the manufacturer’s warranty.
The installation of a portable generator on a home circuit should only be done by a licensed electrician. Under no circumstance, one should try and connect a generator to the home circuit by himself.
FAQs
What is a floating neutral generator? ›
A floating neutral generator's neutral circuit is not connected to the generator's frame or the ground, meaning it is required to connect the neutral to your existing panel neutral.
What is a bonded generator? ›So, grounding is the intentional connection between the neutral wire and the grounding means of the generator, which includes its frame. The term "bonding" is also used to describe the intentional electrical connection of components such as the gas tank or engine to the frame of the generator.
Are Generac generators bonded or floating neutral? ›All Generac permanent residential air-cooled generators are floating neutral generators. The neutral conductor is not bonded to the equipment grounding conductor or to the generator frame.
What is the difference between the two types of generators? ›There are two fundamental types of generators known as AC (alternating current) and DC (direct current) generators. While the technique of producing electricity is the same in both types, AC and DC power become different in terms of their applications – the way in which loads receive electric power.
What does it mean floating neutral? ›A “floating” neutral occurs when the connection to the ground breaks or becomes loose, which causes the neutral bar to “float.” This can happen in your panel or between the utility and your electric panel. It can be caused by a mechanical issue or other issues like rust or corrosion.
What does bonded neutral mean? ›In a bonded neutral generator, the neutral is bonded to the generator's frame. The transfer switch, must in this case transfer the neutral to meet the safety standards according to NEC (National Electrical Code) article 250.
Can you bond a floating neutral generator? ›That's not the case with a floating neutral generator, and you just need to add a Neutral Ground bonding plug in any of the unused 20-amp outlets on the generator. Note that this generator bonding plug must NEVER be used inside of your RV or residence as that would put the neutral ground bond in the wrong place.
Does a bonded neutral generator need a ground rod? ›When using just the extension cords, you do not need to use a ground rod. (If you have a bonded neutral portable generator. This can be found in the owner's manual.)
What does a floating ground mean on a generator? ›High Voltage Power Supplies & Safety Information
The term floating ground (FG) is used to describe an option that allows for very accurate ground referenced load current measurements to be made. Whatever current flows out of the high voltage output of a supply, must return via the ground referenced return path.
Neutral wires are usually connected at a neutral bus within panelboards or switchboards, and are "bonded" to earth ground at either the electrical service entrance, or at transformers within the system.
When would you use a floating neutral generator? ›
The floating neutral configuration is common for applications such as connection to a recreational vehicle and connection to home power where the transfer switch does not switch out the neutral to ground connection.
Are champion generators floating neutral? ›Most Champion Power Equipment generators have a "floating neutral", meaning that the neutral circuit is not connected to the frame or to earth ground. This also means that both legs on the receptacle are hot legs, which is normal for floating neutral generators.
Are Honda generators bonded or floating neutral? ›In most Honda portable gas generators the neutral circuit is not bonded to the frame of the generator or to the earth ground lead; and are commonly called Floating Neutral generators.
What are the 3 types of generators? ›- Inverter generators are ideal for camping, boating and other recreational activities. ...
- Whole house generators (home standby generators) are the best generators for home use.
Diesel Generator
These types of generators are more durable because the low burning temperature of diesel puts less strain on the engine. Diesel generators are more fuel-efficient than gasoline generators, so you'll spend less money over time on the diesel generator.
There are three main types of generators: portable, inverter and standby.
What is the difference between floating and grounding? ›Circuits connected to a grounded power source, like an electric wall outlet, will be electrically tied down and referenced to the Earth, which is abbreviated GND. Power sources that are not electrically connected to the Earth, like a battery, are referred to as floating sources.
What happens if neutral is not grounded? ›If the grounded (neutral) service conductor is opened or not provided at all, objectionable neutral current will flow on metal parts of the electrical system and dangerous voltage will be present on the metal parts providing the potential for electric shock.
Why do I have voltage between neutral and ground? ›The most common reason one finds excessive neutral to ground voltages is due to an illegal neutral to ground bond in a sub-panel. There is one place and one place only that the neutral and ground are bonded together, and that is at the first service disconnect.
What happens if neutral and ground are not bonded? ›If the ground is not bonded to neutral, then the entire ground circuit in the building becomes close to hot until the circuit breaker trips. Ground rods can have several ohms of resistance to ground, which is far too high to keep the ground to safe Voltage in such a situation.
How do you check floating neutral? ›
Condition (2) – Neutral is Floating
In that situation, if you put a voltage Tester with a neon lamp onto the Neutral wire it will glow just as if it was Live, because it is being fed with a very small current coming from the Phase supply via the plugged-in appliance(s) to the Neutral wire.
For a single phase generator, by connecting the neutral to earth you are ensuring that the neutral always remains at or about earth potential, that makes the neutral 'neutral and the phase 'phase. It also provides a return path for earth leakage currents, through the earthing system back to neutral.
When should neutral and ground be bonded? ›If your electrical panel is the first service disconnect point, AND the utility has only provided normally current-carrying conductors (phase and neutral wires), then YES, you must make a neutral-to-ground connection (i.e., 3-phase/4-wire or 1-phase/3-wire).
What type of protection is needed for bonded neutral generators? ›(B) Bonded Neutral Generators
Bonded generators shall be provided with GFCI protection on all 125-volt, 15- and 20-ampere receptacle outlets. Informational Note: Refer to 590.6(A)(3) for GFCI requirements for 15-kW or smaller portable generators used for temporary electric power and lighting.
Bonding is the connection of non-current-carrying conductive elements like enclosures and structures. Grounding is the attachment of bonded systems to the earth. Both are necessary to safeguard people and property from electric hazards.
What happens if you bond neutral and ground in subpanel? ›With ground and neutral bonded, current can travel on both ground and neutral back to the main panel. If the load becomes unbalanced and ground and neutral are bonded, the current will flow through anything bonded to the sub-panel (enclosure, ground wire, piping, etc.) and back to the main panel. Obvious shock hazard!
Why do you not bond neutral to ground in subpanel? ›So, why do you separate the ground and neutral in a subpanel? Because when we bond them together, it gives your neutral wire (the one carrying electrical currents BACK to the source) multiple pathways. That's how the chassis of some equipment will become energized.
Can I use rebar as a grounding rod for generator? ›For a grounding system to be effective, it needs to have good conductivity. Rebar does not have as much conductivity as the more common grounding rod options. It is not as effective at dissipating static electricity. A grounding system made up of rebar may not reliably perform its job if an electrical surge did happen.
What happens if you don't ground a generator? ›Failure to ground a generator is hazardous and can lead to: Electrical overload on your generator which can damage the wiring or other sensitive parts of the electrical system, unless your generator has overload protection like all the generators at DuroMax. Electrocution from touching ungrounded metal.
Do I need a neutral if I have a ground? ›In case of grounding wire at the main circuit breaker panel, its size is dependent on the incoming service wires. If wired properly, we can use neutral as ground wire. We cannot use ground as neutral as it doesn't provide the normal return path for the current.
Do I need the neutral wire from a generator? ›
It's not always necessary to separately ground the generator neutral conductor, but if you do, you may need to switch a load neutral along with its phase conductors when transferring loads between power sources, particularly when you use ground fault protection.
Why does the neutral need to be bonded? ›The Answer:
Neutral-to-ground bond is needed to properly operate the circuit breakers. Over Current Protection Devices (OCPD) such as circuit breakers and fuses actually require a short and intense INCREASE in electrical current (a short) in order to detect the fault and cut the circuit off.
Neutral wire carries the circuit back to the original power source. More specifically, neutral wire brings the circuit to a ground or busbar usually connected at the electrical panel. This gives currents circulation through your electrical system, which allows electricity to be fully utilized.
Are DuroMax generators bonded neutral? ›DuroMax open frame Generators are considered Floating Neutral Generators. This means that they do not have a bond from the Generator frame to the neutral.
When would you use a floating power supply? ›The main applications of floating power supplies are power supplies for micro-channel plates used in detectors of mass spectrometry, power supplies for filaments of anode-grounded X-ray tubes, power supplies for filaments, grids, bias, and electrostatic lenses of scanning electron microscopes (SEM), and transmission ...
Do generators have to be perfectly level? ›That system works well if the unit is on level ground. But if you park the generator on a slope (usually more than 10 degrees), the dippers can't reach all the oil, and some engine parts run dry. That's a recipe for catastrophic failure. So always place your generator on a level surface.
How do you convert a generator to floating neutral? ›Using a wrench or a screwdriver, remove the screw or bolt from both the neutral and the ground connections. Insert the bonding jumper wire into the connections. Tighten the screws or bolts again. Once the conversion is done, put a label on the generator which clearly indicates the changes made.
Should I ground my Champion inverter generator? ›We recommend earth grounding all generators and inverters for additional safety. All Champion generators and inverters are provided with a ground terminal either on the panel or on the frame for this purpose.
Is the Honda eu2200i a floating neutral? ›All Honda inverter generators are Neutral Floating except for the EU6500 and EU7000.
Do Honda portable generators need to be grounded? ›If the portable generator is providing electric power to a structure by connection via a transfer switch to a structure (home, office, shop, trailer, or similar) it must be connected to a grounding electrode system, such as a driven ground rod.
Why use a floating neutral on a generator? ›
The floating neutral eliminates the potential of being shocked by contacting a hot leg and the generator frame at the same time, which could occur if an electrical device such as a hand held tool suffered from an internal short circuit.
Do floating neutral generators need to be grounded? ›Most modern generators don't require grounding because they either ground through the frame or your home's/RV's grounding wire. However, if you are powering your house with a floating neutral transfer switch that gets disconnected from the ground when switching to a portable generator, you must additionally ground it.
Are Honda generators floating or bonded neutral? ›In most Honda portable gas generators the neutral circuit is not bonded to the frame of the generator or to the earth ground lead; and are commonly called Floating Neutral generators.
What is the difference between grounded and floating power supply? ›Circuits connected to a grounded power source, like an electric wall outlet, will be electrically tied down and referenced to the Earth, which is abbreviated GND. Power sources that are not electrically connected to the Earth, like a battery, are referred to as floating sources.
Do you have to ground a floating neutral inverter generator? ›It depends on the application. When using just the extension cords, you do not need to use a ground rod. (If you have a bonded neutral portable generator. This can be found in the owner's manual.)
Are most generators neutral bonded? ›Most Champion Power Equipment generators have a "floating neutral", meaning that the neutral circuit is not connected to the frame or to earth ground.
Which is more important grounding or bonding? ›The two terms are in no way interchangeable, and the life-saving benefits gained by grounding equipment are not replicated by merely bonding the equipment. These are two distinct procedures and both are essential when installing metal electrical enclosures, boxes, and equipment within any electrical system.
What happens if neutral and ground are bonded in subpanel? ›With ground and neutral bonded, current can travel on both ground and neutral back to the main panel. If the load becomes unbalanced and ground and neutral are bonded, the current will flow through anything bonded to the sub-panel (enclosure, ground wire, piping, etc.) and back to the main panel. Obvious shock hazard!