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Bonded Neutral vs. Floating Neutral Generators: What's the Difference?
If you've just purchased a generator, or you're in the middle of having an electrician connect one to your home, there's a reasonable chance you've come across the terms "bonded neutral" and "floating neutral". There's an equally reasonable chance that you nodded politely when your electrician explained this, and then quietly wondered what on earth any of it meant. Don't worry. Your friends at WEN are here to demystify it.
For most people using a generator during a power outage, and using extension cords to power their devices, this question doesn't come up at all. But if you ever plan to connect your generator to your home using a transfer switch, or if you've just bought a new generator and want to understand it a little better, it's worth knowing what these terms mean and why they exist.
The Short Answer
Terrible electrical puns aside, the shockingly short answer is that it depends on your use case.
- If you're running extension cords off your generator on a jobsite, or using extension cords to run appliances in a power outage, you don't really need to worry about whether your generator is bonded-neutral or floating-neutral. (That said, you do need to follow all safety instructions in your owner's manual, especially regarding proper grounding.)
- If you're connecting your generator to your home via a transfer switch, or to an RV, your generator's bonding configuration matters more. Read on for more info.
An Electrical Primer
First, a quick refresher on the basics of electricity. (It will be simplified and brief, we promise, unlike the physics class you slept through in high school.) In a standard electrical system, such as your home's wiring, there are three types of wires doing three different jobs:
- Hot (usually black or red, also known as "live"): this wire carries electrical current from the power source to whatever you've got plugged in (the load).
- Neutral (usually white): this wire provides the return path for current after it's been used. It completes the circuit.
- Ground (usually green, green and yellow, or bare copper): this wire isn't part of the normal flow of electricity at all. Instead, it provides a safe path for electricity to travel in the event something goes wrong (like a short circuit) so that a fuse or circuit breaker trips before anyone or anything gets hurt.
In your home's main electrical panel, the neutral and ground wires are connected to each other at exactly one specific location. This connection is called a neutral-ground bond. The National Electrical Code (also known as the NEC, or NFPA 70; the standard that governs electrical installations across the US) is very clear that there should be exactly one of these bonds in any given electrical system - no more, no less. Think of this bond like the "zero" mark on a ruler. Without an agreed-upon reference point, measurements don't mean anything. In electrical terms, without a single, definitive neutral-ground bond to use as a reference, the system can behave unexpectedly.
The Name's Bond
A bonded-neutral generator has its neutral wire connected to the generator's metal frame (i.e. connected to the generator's own ground) inside the generator itself. The generator carries its own neutral-ground bond.
This diagram shows a home electrical panel connected to a load, like a light (left). This is how your house is set up. A bonded-neutral generator operates very similarly (right); the neutral and ground wires are bonded inside the generator itself.
This is appropriate for a generator being used as a fully self-contained, standalone power source; for example, one powering tools and appliances directly through extension cords, without any connection to your home's wiring. In that configuration, the generator is its own isolated electrical system, and the NEC is perfectly happy with the single bond inside the generator.
Whatever Floats Your Boat
A floating-neutral generator does not have its neutral wire connected to the generator's frame inside the generator. The neutral "floats", and has no fixed connection to ground within the generator itself.
This diagram shows a home electrical panel connected to a load, like a light (left). This is how your house is set up. A floating-neutral generator operates a little differently (right); the neutral and ground wires are separated.
This might sound a little strange at first, but it's by design, and it's actually very common in portable generators. If you plan to connect your generator to your home via a transfer switch, remember that your home's main electrical panel already contains a neutral-ground bond, as discussed above. That bond needs to stay put - it's the single reference point the NEC requires. A floating neutral generator is designed to work with this setup: when connected to the transfer switch, the panel's bond does its job, and there's no competing bond inside the generator to cause problems.
As an aside, if you're running your generator with extension cords, and your generator has GFCI outlets, they may nuisance trip or operate improperly. This is because GFCI devices rely on a neutral-ground reference point to detect any imbalances in the circuit.
There Can Be Only One
If you're an immortal Scottish warrior, you already know this. The NEC's one-bond rule isn't a technicality. It's there for good reasons.
Two neutral-ground bonds in the same system creates a phenomenon called a ground loop. Ground loops cause stray currents to flow through the ground wiring, which, as mentioned above, isn't supposed to carry current under normal circumstances. These stray currents can cause a range of problems: interference with sensitive electronics, unexpected behavior in GFCI outlets and circuit breakers, shock hazards, and, in serious cases, fires or equipment damage.
In brief, one bond is right. Two bonds is trouble.
So What Do I Do?
As mentioned above, it depends on how you use your generator.
Using your generator with extension cords
If you're running extension cords directly from your generator to your appliances (which is how most people use a portable generator during a power outage) the bonded- vs. floating-neutral distinction generally doesn't affect you. Both types of generators will work fine in this configuration, and you don't need to do anything differently.
Connecting to your home through a transfer switch
This is the situation where it really matters. When a generator is connected to a home via a transfer switch, the two electrical systems are joined together, and the NEC's one-bond rule comes directly into play. In most (but not all) cases:
- A floating neutral generator can be connected to most transfer switches without any modification of the bond, since the single neutral-ground bond lives where it should: in your home's main electrical panel.
- A bonded neutral generator connected to a transfer switch may result in two bond points (one in the generator, one in the home panel), which is exactly the problem described above. In this situation, a licensed electrician may need to disconnect the neutral-ground bond inside the generator before the installation is complete.
- Some transfer switches are specifically designed to handle bonded-neutral generators and manage the bonding situation on their own. Your transfer switch's owner's manual should also explain whether or not it has this capability, which is known as "switching the neutral". Your electrician will also know which type you have and how to handle it.
NOTE: Transfer switch installation should ALWAYS be handled by a licensed professional electrician. NEVER connect a generator directly to your home's wiring without a properly installed transfer switch. Doing so, a practice known as backfeeding, is dangerous, illegal, and could seriously injure or kill utility workers attempting to restore power. For a more in-depth look at transfer switches and how to choose one, check out our comprehensive guide to generators and transfer switches.
Connecting to an RV
Depending on your RV model, your RV may require a bonded-neutral or floating-neutral configuration, especially if it has a built-in surge protector Energy Management System (EMS), which may check for proper neutral-ground bonding and refuse to pass power if the connection doesn't match what it expects.". Your RV owner's manual should specify. If you see strange behavior when attempting to connect your generator to your RV, especially if trying to run the air conditioning or charge the RV's batteries, it may be a bonding issue. Consult your RV owner's manual, and consider temporarily bonding the neutral and ground using a neutral-ground bonding plug. This is a plug that can be inserted in a standard 120V outlet, and allows you to quickly troubleshoot potential bonding issues. For prolonged use, however, if your use case requires a bonded-neutral generator, it's best not to rely on these plugs.
Parallel Operation
If you're running two inverter generators in parallel using a parallel kit, the bonding situation matters here as well. As we discuss in our article on parallel kits, the NEC requires one neutral-ground bond across the whole system. Make sure your setup is configured correctly. If you're not sure, ask a licensed, professional electrician.
How do I know which type my generator has?
On most WEN generators, the control panel indicates which type you have - "floating neutral" or "neutral floating" means you have a floating neutral generator. "Bonded neutral", or "neutral bonded to frame" means you have a bonded neutral generator.
"Neutral floating" marking on a WEN TF1450X control panel.
"Bonded neutral" marking on a WEN TF1500XR control panel.
"Neutral bonded to the frame" marking on a WEN DF680iX control panel.
Alternatively, check your generator's owner's manual. It may describe the generator's neutral as "bonded neutral", "bonded", "floating neutral", or "floating." If you have a WEN generator, the most recent version of the manual is available as a PDF on your model's product page at wenproducts.com — just search your model number in the search bar at the top of the page. You can also check the generator's wiring diagram.
If the manual doesn't specify, or if you're not sure how to interpret what it says, contact us. We can tell you exactly which type your generator has.
As an aside, there may also be a label for the DC system on your WEN generator's control panel. It likely says "system floating". This means that the DC circuit's negative wire floats relative to ground; that is, it is not bonded.
"System floating" marking (DC circuit only) on a WEN DF680iX control panel.
Conversion
If you need to change your generator from a floating neutral to a bonded neutral, or vice versa, it's best to have a professional electrician do so. If your electrician needs specific guidance, please contact us for instructions. Also, be sure to affix a clear note or warning to the generator indicating its new configuration.
Summary
Thanks for reading. In short: a bonded neutral generator has its neutral wire connected to its own frame; it carries its own neutral-ground bond. A floating neutral generator does not; its neutral has no fixed connection to ground inside the generator. For most people running extension cords, it makes no practical difference. For anyone connecting a generator to their home through a transfer switch, it matters enough to discuss with your electrician before the installation.
If you have any questions about your WEN generator, or just need some guidance on how your setup should be configured, please feel free to give us a call at 1-847-429-9263 (M – F, 8 – 5 CST), or drop us a message here to talk to our friendly and knowledgeable technical support team. Also, check out some of our other helpful articles about generators and home backup power.
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