# Floating Neutral



## tvl (Nov 14, 2018)

I continue to have questions or concerns about generators with floating neutrals and their use in a *STANDALONE* mode.

** Standalone meaning any or all loads are plugged directly into the generator via an extension cord ....... the generator is NOT connected to a home's electrical panel in any way whatsoever!*

In an effort to make things flow more smoothly, I would like to begin with just two questions:

1) When a generator utilizes a floating neutral, does it "act" much like an isolation transformer?

2) If this is true, then how would an appliance that develops an earth fault (_for example a live conductor has shorted to the chassis_) trip the overload on the generators receptacle? In my mind, it would not nor could not trip an overload or blow a fuse when wired with a floating neutral AND being utilized in a standalone mode.

All thoughts would be very much appreciated ..................... and likely more questions will evolve.


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## motormonkey (Jul 10, 2016)

"1) When a generator utilizes a floating neutral, does it "act" much like an isolation transformer?"

It certainly could, but given that most generator windings are configured as line-neutral-line 240, allowing that entire circuit to float could create several dangerous situations, and it gets complicated. For starters, the generator, and any appliances connected in such an arrangement are not designed to operate that way.

2) If this is true, then how would an appliance that develops an earth fault (_for example a live conductor has shorted to the chassis_) trip the overload on the generators receptacle? In my mind, it would not nor could not trip an overload or blow a fuse when wired with a floating neutral AND being utilized in a standalone mode.

If an appliance connected to a floating ground generator developed a full ground/line short circuit as you describe, it would likely not trip any overload breakers. You would essentially have created a bonded ground/line situation instead of a bonded ground/neutral situation. In a generator with a line-neutral-line winding configuration, there would still be 120 volts between neutral and either line, BUT there would effectively be zero voltage to ground on the affected line conductor, there would be 120 volts to ground on the neutral conductor, and there would be 240 volts to ground on the opposing 120 volt line. Many appliances might well operate normally in this situation, but as I said previously, it could create several dangerous situations.

This is why the neutral must be bonded to ground in standalone uses.


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## tvl (Nov 14, 2018)

Thanks motormonkey!

1) You stated: *"but given that most generator windings are configured as line-neutral-line 240"*
I should have mentioned that for my situation I was referring to our Honda EU3000is which provides ONLY *120 VAC*. The unit is NOT capable of providing 240 VAC

2) You also stated: *"This is why the neutral must be bonded to ground in standalone uses"*
Therefore, I'm assuming that in my situation it is important that I bond the neutral to the ground lug if it will always be used in a standalone mode ................ which is the ONLY way I ever intend to use it! And, by the way, I have already buried an 8 foot grounding rod at the location the generator will be used so that I can properly ground the generator.

I've spoken with the individuals at the business which sold me the unit and no one seemed to know how to address this issue. They would only indicate that I needed to ground the unit, but I should not in any circumstance try to bond the neutral to ground. ???????????????

And lastly, the question of bonding the neutral to ground. I could open up the unit and "hard wire" it *OR* I've seen where folks take a 3 pronged pug and link the *neutral* and *ground* together. When this plug is inserted into one of the receptacle's of the generator, it effectively bonds the neutral and ground wires. Is this latter method acceptable? If not, why!

Thanks again to all that reply!


*As an afterthought*: _In my situation with a generator that ONLY provides 120 VAC and is utilized ONLY in standalone mode, is there just reason why I should NOT consider bonding the neutral and ground? Possibly there is a not so obvious reason for not doing so??????????_


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## iowagold (Jan 22, 2020)

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## tvl (Nov 14, 2018)

Thanks for the reply!

I do understand the importance of using a ground rod and have already made arrangements to do so. However, my concern is with the floating neutral* AND* using the generator as a standalone unit. In other words, the generator is NOT being tied to the house service and therefore is not getting the benefit of having the neutral tied to ground.

For me it's a question of safety *AND* I simply want to ensure I'm not in any way creating some other type issue when I tie the neutral to ground. I wouldn't think so, but then I'm certainly not a generator expert! I know the folks at the business where I purchased the unit have no idea as to what should be done. I guess they just sell the equipment!


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## motormonkey (Jul 10, 2016)

Most small generators come from the factory with the ground conductor and the neutral conductor bonded together. Check the continuity between those two conductors and see. The neutral may well already be bonded to ground.


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## tvl (Nov 14, 2018)

Thanks again motormonkey!

No, the neutral is NOT bonded and I have verified with a meter!

The manual for the generator also states: *"Neutral Floating: The generator (stator winding) is isolated from the frame and from the AC receptacle ground pin"*

I would like your opinion on bonding the neutral to ground. I could open up the unit and "hard wire" things *OR * I've seen where folks take a 3 pronged plug and link the *neutral* and *ground* together. When this plug is inserted into one of the receptacle's of the generator, it effectively bonds the neutral and ground wires. Is this latter method acceptable? If not, why! It's certainly easy and would not void my warranty if done this way.

Thanks again!


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## motormonkey (Jul 10, 2016)

"...take a 3 pronged plug and link the *neutral* and *ground* together..." That will work just fine. The only down side is that it occupies one of your receptacles.


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## tvl (Nov 14, 2018)

Thanks so very much motormonkey! I'll make one today!

I'm assuming there are many individuals that operate their generator in a standalone mode and never worry about bonding their generator's neutral to ground .............. and most probably aren't even aware of the potential issues. I'm also sure most of these individuals have never encountered an issue operating in this manner, but I'm simply trying to do things correctly AND safely! Thus my reason for pursuing this matter. *Again, thanks for your time and help!*

TV


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## iowagold (Jan 22, 2020)

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## tvl (Nov 14, 2018)

iowagold said:


> one quick question.
> what brand and model of gen set are we working with?


It is a Honda EU3000is

Yep, I already had a plug rated for 125 VAC - 20 amps. I used that with # 12 wire.

I imagine a "hard wired' bond is preferred, but the plug will suffice and I won't need to open up the case for bonding. I was worried that might affect my warranty?

Thanks everyone!


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## iowagold (Jan 22, 2020)

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## tvl (Nov 14, 2018)

*Just a quick update: *

I've taken an electrical plug and applied a short piece of wire between the neutral and ground pins. When the plug is inserted into the outlet of my Honda EU3000is generator, which shipped with a floating neutral AND is only used in a standalone mode, the generator then becomes a bonded neutral/ground piece of equipment. Of course, the generator is also tied to an 8 foot grounding rod to ensure it is properly grounded to earth.

I keep trying to understand the *importance* of properly bonding when necessary and also the importance of when not to. The following statement was found online this evening and I felt it was the best explanation I've yet come across:

_"The neutral is tied to ground just to give the system a ground reference. It prevents the potential of the system from rising too high above that of ground. It also allows breakers to trip in the event that an ungrounded conductor faults to ground. Without the neutral being connected to ground, an ungrounded conductor contacting ground would not trip a breaker.

The system will still function perfectly fine without the neutral being connected to ground. The current returns to its source (the windings) via the neutral, not to ground."_

Unless I'm still missing the point, it's always best to bond the neutral & ground *AND* then properly ground the generator before using. It prevents encountering a shock should a fault develop AND it also ensures the onboard breaker is tripped. Again, this ONLY applies to a generator being used in a standalone mode which was also shipped with a floating neutral configuration .............. which was my situation.

If my statements are incorrect, I'm sure someone will chime in and let me know. Otherwise, maybe this thread will help someone in the future should they be searching for how to handle the operation of their floating neutral generator!


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