Floating the neutral on portable generators.

ACDCBag420

Member
Location
Rutlant Vermont
Occupation
Solar
My question is about floating the neutral on portable generators. I have a stand alone pv system with a generator input and I would like to not have to buy another generator with a floating neutral. My portable generator has a bonded neutral, I have taken it apart and successfully floated the neutral. I have seen some manufactures of portable generators provide instructions on how to break the neutral ground bond and float the neutral. Unfortunately I have called Dewalt and they said plainly do not tamper with the product. The method of breaking the neutral ground bond on the Dewalt was the same as all the other portable generators, the only difference is that they make no mention of the procedure in the product literature and were no help on the tech support line. Is it common practice to break the neutral ground bond on portable generators when an application for a floating neutral is needed? If the manufacturer does not provide examples of how to do this would it be any different breaking the neutral ground bond on their product versus one that specifies how to do it? Would like some feedback I don't want to plug this thing in and damage something even though my gut feeling says it fine. Any thoughts? Thank you very much I am only a second year apprentice and could use some advice from more experienced colleagues.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I have a Generac portable generator and I unbonded the neutral for use as a backup source for my house. Other than possibly voiding the warranty I see no issue with doing so. In my generator I was able to do it in a nondestructive way so it could easily be re-bonded if there is a warranty issue down the road.
Generac Neutral 001.jpg Generac Neutral 002.jpg
 

ACDCBag420

Member
Location
Rutlant Vermont
Occupation
Solar
Hey thank you for the timely response. So in this system, and I am also going to post on the outback power forum as well, the generator will be feeding an ac input for an inverter. The inverter can take an ac input from a generator or the grid and will use this power to charge batteries or provide the house loads. Is there any special startup procedure I should follow out of caution? From what I was reading It sounds like I should start the generator with the chord plugged in so it can have a neutral to ground reference. Probably over thinking things but this equipment is very expensive so any mistake would be costly. Obviously I always would recommend buying the right equipment as in a generator with a floating neutral but just was not sure if it was common practice to float the neutral on a portable. Thanks again for the help.
 

ACDCBag420

Member
Location
Rutlant Vermont
Occupation
Solar
Also the picture really helps, this is the same method of floating the on the Dewalt generator. The picture confirms my method and is the same as other methods provided by some manufactures. again this information was not provided by Dewalt hence my confusion.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Also the picture really helps, this is the same method of floating the on the Dewalt generator. The picture confirms my method and is the same as other methods provided by some manufactures. again this information was not provided by Dewalt hence my confusion.
I just tightened the bolt and insulated the splice in the neutral. I'm no PV guru so I'll let others respond to the PV questions.
 

jaggedben

Senior Member
Hey thank you for the timely response. So in this system, and I am also going to post on the outback power forum as well, the generator will be feeding an ac input for an inverter. The inverter can take an ac input from a generator or the grid and will use this power to charge batteries or provide the house loads. Is there any special startup procedure I should follow out of caution? From what I was reading It sounds like I should start the generator with the chord plugged in so it can have a neutral to ground reference. Probably over thinking things but this equipment is very expensive so any mistake would be costly. Obviously I always would recommend buying the right equipment as in a generator with a floating neutral but just was not sure if it was common practice to float the neutral on a portable. Thanks again for the help.
I think you have it correct. Your neutral will be grounded and bonded at some other point in the system, such as the service entrance. You do not want the neutral bonded to ground at multiple points on the premises. You also do not not want the generator operating without the neutral bonded. So to operate the generator the neutral has to be connected to the rest of the system, where the neutral is bonded elsewhere. There would be something to be said for having it permanently connected, rather than a plug connection.
 

jaggedben

Senior Member
What you are doing here is defeating built in safety features and replacing them with your own installation or design. Whenever you do that sort of thing you're going to be jeopardizing warranties and probably violating code, even if what you are doing is safe. Something to think about is what happens when someone unfamiliar with your setup comes along and has to use it or work on it.
 

ACDCBag420

Member
Location
Rutlant Vermont
Occupation
Solar
Thank you jaggerben for the great input. This is part of my dilemma, i'm not sure if this is a common modification to portable generators for home backup or if its a brand specific mod. I have seen some that provide instructions about floating the neutral and others that do not including my Dewalt which does not.
 

ACDCBag420

Member
Location
Rutlant Vermont
Occupation
Solar
I think what ill do is test the output by running some loads with a floated neutral on a standard distribution panel. If the voltages are not abnormal and everything works fine I will call it good.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
One thing to consider is that any GFCI receptacles on the generator will not provide ground fault protection unless the neutral on the line side of these GFCIs is bonded to equipment ground somewhere (e.g., inside the generator or in the panel of your PV system when it's connected to the generator). So if you ever want to use the portable generator in a standalone mode but the internal neutral bond has been removed, perhaps it would be a good idea to have a twist-lock plug made up with its neutral to ground terminals bonded so you could insert it to make the GFCIs functional again.
 

ACDCBag420

Member
Location
Rutlant Vermont
Occupation
Solar
Yea I did see that about the twist lock plug in a different forum, i'm glad that is a well documented work around. So yea I think i'm going to go ahead and run this it sounds a pretty common fix.
 
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