Neutral in Generator


Old 08-24-05, 07:41 PM
Old man
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Neutral in Generator

I was reading some of the threads and think I may have another problem.
I am trying to hook up my portable generator for home use. I got a transfer switch and the connector cord, 4 prong twistlock. I saw in another thread about neutral and ground in a generator.
Mine says "Neutral Bonded to Frame" now I understand it is only to be bonded in one place, the service panel and it is bonded there.
My transfer switch does not switch neutral. So I would like to know how to make my generator a floating neutral, possibly on a switch so it would be easy to convert back and forth for stand alone use also. I have a wiring diagram, but cannot post attachments.
Any ideas?
The manufacturer was not much help when I called them, I have spoken to them twice and got 2 different answers, neither of which seems right.
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Old 08-26-05, 01:56 PM
Join Date: Apr 2004
Location: Ontario Canada
Posts: 1,767
You simply need to get a 3 pole transfer switch.
Old 08-26-05, 03:18 PM
Join Date: Apr 2005
Posts: 37
Here is a good explanation with illustrations explaining a seperately derived system and switched neutral for portable generators.

Hope this helps.

Old 08-26-05, 09:49 PM
Join Date: Aug 2004
Location: NA
Posts: 1,065
To use a portable generator that has the neutral bonded to the frame and connect it to a transfer switch that doesnt switch the neutral will create a parallel path for the neutral current on the egc. The generator bonded neutral must be unbonded from the frame as he states in order to connect it to the transfer switch he has in place. You can do this but it it isnt real cut and dry as you might expect. It requires dismantling the control panel and tracing and unbonding the neutral and isolating it. Ive never heard of switching it but that sounds doable. Most diyer's operate these portable generators incorrectly and arent aware of the bonded neutral conflict and parallel current on the egc. You would not drive a round rod as you might see in the instructions. This will not be a seperately derived system and will be grounded at the service through the egc from the generator cord.
Old 08-26-05, 11:24 PM
Old man
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Roger, you are right on the money. I do not want to use it for house use until I get the neutral isolated from the ground. There are thousands of them out there being used just as they are sold, and almost all portable generators are bonded neutral.
I have called Porter-Cable and they are no help, says it is fine like it is. I called 2 Porter-Cable service centers and they both stated they did not know how to make the neutral floating and had never been asked to change one over.
If there is an electrician here, I can email the wiring diagram in pdf. format for you to look over, I think I see the changes need to be made, I just would like a knowledgeable second opinion.

Thanks, Mike
Old 08-27-05, 08:31 PM
Join Date: Oct 2004
Location: USA
Posts: 255
Old man,

For safety sake, I wouldn't do it. The reason for not lifting the neutral is to prevent a potential difference from existing between you and your generator and frame. Through a cable run to your panel; your wire and connections will have some resistance which in turn will produce a voltage drop which could be deadly at your generator with respect to your panel and wire. With the neutral tied to the generator; it will shunt any voltage to ground at the generation point. Also, this could be abusive to the generator's armature.

Yes, you may lose some current output due to the shunt but then this will be proportional to the resistance of your line and the resultant voltage drop which could have ended your life.

God Bless,
Old 08-27-05, 09:27 PM
Join Date: Aug 2004
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Posts: 1,065
Dave there is a lot of controversy over this and you have a difficult time getting agreement. My understanding is that you are not disconnecting the neutral from the generator winding only from the frame to prevent an alternate path on the egc for neutral current when connecting to a transfer switch. You would want the bond for cord and plug powered equipment which is why a lot of people say to use cords to power critical house appliances like your refrigerator when using portable generators because of this neutral connection to the frame. Permanent emergency standy by generators dont have this bonded neutral to frame and and switch the service neutral by design making them seperately derived systems.
It would be nice to hear from the NEC about this someday and clear this controversy up.
Old 08-27-05, 09:38 PM
Old man
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I think I know what you are talking about. I am not an electrician by any means.
My main concern is my transfer switch does not switch neutral and a sticker inside says generator must have floating neutral. I purchased my generator about 3 years ago and have been using extension cords when power outages occur. But that is a big hassle.
All the transfer switches I can find do not switch neutral and I know the code says it can only be bonded in one location { the service panel } I have called the service centers and they say they have never switched one to neutral floating.
What will happen if I hook it up like it is? I know it will create a loop in the neutral, as it says on the generator the neutral is bonded.

I just do not want to endanger linemen by possibly feeding current out through the neutral. From the wiring diagram, it appears to be an easy fix, but like I said I am not an electrician. I would like someone more knowledgable than myself to look at it and give me their thoughts.

Any info will be appreciated.


Last edited by Old man; 08-27-05 at 09:45 PM. Reason: addition of info
Old 08-27-05, 09:53 PM
Join Date: Jan 2004
Location: Oregon
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Old 08-27-05, 09:59 PM
Join Date: Aug 2004
Location: NA
Posts: 1,065
I suppose we could go on forever with this. Winnies links are probably the best for clearing this up that I have seen lately.

Go here for lots and lots of discussion by professionals on this subject. Be prepared for an avalanche of disagreement.

Use the search option and click the drop down arrow for the forum you want to search. Choose grounding and bonding. Then keyword search "generator"

Last edited by Roger; 08-28-05 at 12:12 AM.

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