# Wiring Generator to Backfeed Breakers - Neutral and Ground Wires?



## electures

What type of interlock device? Who makes it?


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## AllanJ

You would use an ordinary breaker for backfeed purposes.

The best way to arrange ground and neutral for a backfed generator is to unbond the neutral from the generator's frame and ground connection inside the generator. Occasionally this cannot be done easily in which case I would be tempted to leave the green wire unhooked somewhere in the wiring between panel and generator. I would not mutilate a generator to get its neutral and ground unbonded.


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## brric

Connect the neutral and the ground wires from the generator to the load center. DO NOT tamper with the generator.


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## stickboy1375

brric said:


> Connect the neutral and the ground wires from the generator to the load center. DO NOT tamper with the generator.


If you cannot remove the N-G bond at the generator, then you must switch the grounded connector at the transfer switch.


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## brric

stickboy1375 said:


> If you cannot remove the N-G bond at the generator, then you must switch the grounded connector at the transfer switch.


And why would that be?


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## stickboy1375

brric said:


> And why would that be?



You can only have one point where your N-G are bonded together.


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## brric

What do you think would be the consequences? It works fine on my personal home and others I have done.


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## andrew79

A generator is not considered a permanent part of the electrical system. Removing the bond in the generator voids the warranty. Also if the generator is used for anything other than back feeding the house it could be potentially dangerous with the bond removed.

Oddly enough this is one of the reason a genny panel switches out the neutral that you argued so much about not needing.

brric, what's you've in essence done is run a ground and a neutral in parallel with each other, in theory they can both carry some of the current.


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## stickboy1375

brric said:


> What do you think would be the consequences? It works fine on my personal home and others I have done.


Its a code violation, plain and simple. And just because it works, doesn't make it correct.


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## brric

andrew79 said:


> A generator is not considered a permanent part of the electrical system. Removing the bond in the generator voids the warranty. Also if the generator is used for anything other than back feeding the house it could be potentially dangerous with the bond removed.
> 
> Oddly enough this is one of the reason a genny panel switches out the neutral that you argued so much about not needing.
> 
> brric, what's you've in essence done is run a ground and a neutral in parallel with each other, in theory they can both carry some of the current.


That is correct. It is a temporary plug and cord connection. It is not intended to be permanent. Also, removing the bond would create a possible generator fault clearing issue.


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## stickboy1375

andrew79 said:


> A generator is not considered a permanent part of the electrical system. Removing the bond in the generator voids the warranty. Also if the generator is used for anything other than back feeding the house it could be potentially dangerous with the bond removed.
> 
> Oddly enough this is one of the reason a genny panel switches out the neutral that you argued so much about not needing.


I didn't argue anything, I told you current doesn't seek the earth.


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## andrew79

i should have clarified, only the last bit of that post was directed at you brric, the first was for stickboy.

never thought of the fault issue, good point.


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## stickboy1375

brric said:


> That is correct. It is a temporary plug and cord connection. It is not intended to be permanent.


And is still a violation.


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## stickboy1375

andrew79 said:


> i should have clarified, only the last bit of that post was directed at you brric, the first was for stickboy.


I know.


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## brric

My research leads me to respectfully disagree.


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## stickboy1375

brric said:


> My research leads me to respectfully disagree.


So where in the NEC do you believe you can have two separate N-G connections? You can always just purchase a generator with a floating neutral, or install a 3 pole transfer switch, the option is yours.


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## brric

Is a portable generator a separately derived system or non-separately derived system?


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## stickboy1375

brric said:


> Is a portable generator a separately derived system or non-separately derived system?


Thats not what determines it, the transfer switch does.

IF you have a solidly connected grounded (neutral) connection, then you do not have a SDS, if you break the grounded (neutral) connection then yes, you do have a SDS, and the generator then requires ground rods.


With that said, you MUST know if the generator you are wiring has a N-G connection before you can make the correct transfer switch selection.


This may help you digest some of the info I posted...http://www.imsasafety.org/journal/ma03/ma5.htm


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## brric

How would you use a 3 pole transfer switch for the OP'S installation?


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## stickboy1375

brric said:


> How would you use a 3 pole transfer switch for the OP'S installation?


The only way you can use a interlock kit legally is if his generator has a floating neutral. Otherwise, he would need a manual 3 pole transfer switch.


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## andrew79

Simpliest thing to do is to wire it up as is and see if the gfci trip on the generator, if it does then the simplest way to get it working is to float the ground coming from the generator inside the panel. Legalities of it can be argued for days. Keep in mind that the code only contains info on how to wire it up to the electrical system. the actual internal generator wiring is a UL standard that has to be followed by the manufacturer.

In all honesty there's a bunch of ways to wire them, if you look in the genny manual it will most likely tell you that you need either a 3 pole or 4 pole transfer switch if it has a bonded neutral inside. If it has a floating neutral then it will recommend a 2 pole transfer switch.

Safest and most expensive way is to leave the generator as is as to not void your warranty and actually spend the money on the recommended transfer switch for your particular unit.


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## Stubbie

tjnoff said:


> Hi! I'm planning on using an interlock kit (code approved model) when connecting my generator to my home's main power panel, as follows (drawing attached):
> 
> 7500W generator (Generac GP7500E) with L14-30 generator cable connecting generator's 240V 30A outlet to an L14-30 inlet box (on house), then connect the inlet box to 30A dual-pole backfeed breakers in the _primary_ power panel using 10/4 wire.
> 
> Backfeed breakers and main panel input breaker will be mutually exclusive using interlock (only one can be on at any given time).
> 
> My question is do I run both the neutral _and_ ground wires from the inlet box to the neutral bus bar in this primary power panel, or just the neutral wire? If just the neutral wire, what's done with the ground feed? Anything?
> 
> One other secondary question: Are backfeed breakers unique from standard breakers? Do I need to find specifically backfeed breakers, or will your standard 30A dual-pole breakers work for this application?
> 
> Thanks for your help!


This would *not* be a separately derived system since your interlock does not open the neutral connection to the utility grounded conductor which has earth grounding both at the service equipment and utiltiy transformer.
Being a non separately derived system the the NEC would require that no neutral to ground bonds exist load side of the service equipment. You would technically, in order to be code compliant, need to determine if the neutral and ground are separated at the generator. In the event you do not isolate then your equipment grounding conductor will be energized due to the connected neutral of the utiltiy at the service equipment of the home with the generator neutral.
Bottom line is portable generators were designed to serve as power sources for job sites and cord and plug equipment not standby power for a home and therefore have neutral and ground bonded in acccordance with 250.30 while considering 250.34(A). Think of them as service equipment.

Now having said that I would venture to say 80% of portable generators powering homes with transfer switches or interlocks that do not switch the neutral do not have their neutrals isolated from ground. NOT because it isn't required but because they simply are not familiar with that rather confusing part of the NEC.

It would be advantageous to all of us to start a new thread about grounding of generators and in particular portable ones and when and when not to requrie ground rods at the generator. I would bet it will generate some eye opening. If we all tie in the NEC articles to back up the discussion I actually think we could reach a professional consensus on the code compliance requirements for grounding portable generators.

I would suggest providing graphics/drawings as well as Nec articles and subsections to make your points would be great. I'll start it and we can see where it goes... It would be better IMO if we do not link to other written articles and provide our own explanations to which others can add.


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## tjnoff

electures said:


> What type of interlock device? Who makes it?


This one: http://www.interlockkit.com/InstrK8210GENewDsn.pdf


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## electures

tjnoff said:


> This one: http://www.interlockkit.com/InstrK8210GENewDsn.pdf


Unfortunately installation of this kit is a violation of 110.3b. Wyle Labs lost its listing capabilities and it is not listed by any other recognized listing labs. Sorry.


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## kbsparky

electures said:


> Unfortunately installation of this kit is a violation of 110.3b. Wyle Labs lost its listing capabilities and it is not listed by any other recognized listing labs. Sorry.


It was my understanding that anything previously listed by Wyle is still in force and legal. Those listings were not revoked.

They are no longer able to list any new products by the recent action of losing their certification.


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## AllanJ

deleted.


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## stickboy1375

electures said:


> Unfortunately installation of this kit is a violation of 110.3b. Wyle Labs lost its listing capabilities and it is not listed by any other recognized listing labs. Sorry.


Interesting....


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## tjnoff

First, thanks to everyone for their thoughtful responses! I hadn't imagined that my query would garner such a lengthy discussion.

Frankly, I was hoping to use the interlock solution in order to make use of all of the circuits in the house during an outage, as you probably have guessed. Having over 20 individual circuits in the house, I didn't want to be limited to powering 10. Not that I'd power all 20-some-odd circuits at once with a 7500W generator, but it would be nice to have the flexibility to pick and choose from all 20 at any given time.

The differing opinions about how or if to connect the ground line in my proposed application leaves me feeling a bit sketchy about using the interlock solution, but I'm not sure that a transfer switch solution looks much different when it comes to the N and G connections.

This video (http://www.youtube.com/watch?v=5dKfVgVvEt8&feature=youtube_gdata_player) shows the neutral and ground wires being used for the Reliance transfer switch solution. In part 1 of this video series (http://www.youtube.com/watch?v=7--oK3BXN5U&feature=youtube_gdata_player), connecting the transfer switch to the power panel is shown, and both the ground and the neutral wires are used and connected to the neutral bar in the main panel. Once the transfer switches are put in the generator position, how does this differ from my interlock solution in regard to the NG connections? There is no mention in the videos about whether the N and G are bonded at the generator or not.

Sounds like a thread on grounding generators would be in order, and I'd like to know if anyone starts one, but I'd still like to know how to handle my situation.


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## stickboy1375

tjnoff said:


> First, thanks to everyone for their thoughtful responses! I hadn't imagined that my query would garner such a lengthy discussion.
> 
> Frankly, I was hoping to use the interlock solution in order to make use of all of the circuits in the house during an outage, as you probably have guessed. Having over 20 individual circuits in the house, I didn't want to be limited to powering 10. Not that I'd power all 20-some-odd circuits at once with a 7500W generator, but it would be nice to have the flexibility to pick and choose from all 20 at any given time.
> 
> The differing opinions about how or if to connect the ground line in my proposed application leaves me feeling a bit sketchy about using the interlock solution, but I'm not sure that a transfer switch solution looks much different when it comes to the N and G connections.
> 
> This video (http://www.youtube.com/watch?v=5dKfVgVvEt8&feature=youtube_gdata_player) shows the neutral and ground wires being used for the Reliance transfer switch solution. In part 1 of this video series (http://www.youtube.com/watch?v=7--oK3BXN5U&feature=youtube_gdata_player), connecting the transfer switch to the power panel is shown, and both the ground and the neutral wires are used and connected to the neutral bar in the main panel. Once the transfer switches are put in the generator position, how does this differ from my interlock solution in regard to the NG connections? There is no mention in the videos about whether the N and G are bonded at the generator or not.
> 
> Sounds like a thread on grounding generators would be in order, and I'd like to know if anyone starts one, but I'd still like to know how to handle


I know i stirred the pot on the issue, but the reality of it is, everyday generators are installed incorrectly by licensed contractors, and the like... Most people don't feel it is a real issue with the multiple N-G connection in a portable generator installation, well, because it still works in the end, and most likely will never be an issue. but still a violation none the less, and under the right circumstances could create a serious issue. Its one of those items that just gets installed either by lack of knowledge, or just the way we do it mentality...


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## tjnoff

stickboy1375 said:


> I know i stirred the pot on the issue, but the reality of it is, everyday generators are installed incorrectly by licensed contractors, and the like... Most people don't feel it is a real issue with the multiple N-G connection in a portable generator installation, well, because it still works in the end, and most likely will never be an issue. but still a violation none the less, and under the right circumstances could create a serious issue. Its one of those items that just gets installed either by lack of knowledge, or just the way we do it mentality...


So, in your opinion (one of several here, I realize), would you float the ground or not do this at all? I'm not of a mind to unbond N and G at the generator. (I haven't found for sure that they are bonded in the manuals yet, but it's a standard Generac portable unit, so I'd have to assume they are.)

And where does grounding the generator itself play into this? Do it or not?


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## stickboy1375

tjnoff said:


> So, in your opinion (one of several here, I realize), would you float the ground or not do this at all? I'm not of a mind to unbond N and G at the generator. (I haven't found for sure that they are bonded in the manuals yet, but it's a standard Generac portable unit, so I'd have to assume they are.)
> 
> And where does grounding the generator itself play into this? Do it or not?


Personally, you can only undo the N-G bond at the generator if it is allowed by the manufacture, with that said, I would just install a 3 pole transfer switch and switch the neutral. Im betting 99% of portable generators contain a N-G bond, and with the growing number of manufactures supplying 30 amp GFCI protected receptacles, you will have no choice to deal with this scenario sooner or later.


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## tjnoff

stickboy1375 said:


> Personally, you can only undo the N-G bond at the generator if it is allowed by the manufacture, with that said, I would just install a 3 pole transfer switch and switch the neutral. Im betting 99% of portable generators contain a N-G bond, and with the growing number of manufactures supplying 30 amp GFCI protected receptacles, you will have no choice to deal with this scenario sooner or later.


So, either float the ground between the generator and the transfer switch or between the transfer switch and the power panel, but pass neutral all the way through to the neutral bar in the power panel, yes?

What about grounding the generator itself outside, as directed in the user's manual?


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## AllanJ

stickboy1375 said:


> Personally, you can only undo the N-G bond at the generator if it is allowed by the manufacture, with that said, I would just install a 3 pole transfer switch and switch the neutral. Im betting 99% of portable generators contain a N-G bond, and with the growing number of manufactures supplying 30 amp GFCI protected receptacles, you will have no choice to deal with this scenario sooner or later.


In this case, with the GFCI protected receptacle, I would consider using an ungrounded but otherwise ordinary extension cord to connect the generator up with. The generator could be put on a platform to reduce any hazards introduced by lack of an equipment grounding conductor.

The only difference between a generator with neutral floating within and the above hookup is that the body of the generator is at neutral potential instead of ground potential.


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## tjnoff

AllanJ said:


> In this case, with the GFCI protected receptacle, I would consider using an ungrounded but otherwise ordinary extension cord to connect the generator up with. The generator could be put on a platform to reduce any hazards introduced by lack of an equipment grounding conductor.
> 
> The only difference between a generator with neutral floating within and the above hookup is that the body of the generator is at neutral potential instead of ground potential.


The goal here is to power circuits in the house with the generator through the main power panel. I'm not sure how I'd do that with an extension cord.

I'm guessing that the issue with a floating ground is that it can have a current potential (vice true ground), and could therefore be a shock hazard... maybe even an explosion hazard on a gasoline generator.

Just removed the cover from my panel. Both bus bars (ground and neutral?) are physically tied together. If I'm right that those are G and N bus bars, they're both at ground potential. 

While I understand electricity fairly well, I'm not sure why having ground and neutral bonded in two places (generator and bus bar) is an issue. They're both at the same potential.

I'm not saying it's not a problem - I apparently don't understand some things here - I'm just not seeing the issue.


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## andrew79

tjnoff said:


> The goal here is to power circuits in the house with the generator through the main power panel. I'm not sure how I'd do that with an extension cord.
> 
> I'm guessing that the issue with a floating ground is that it can have a current potential (vice true ground), and could therefore be a shock hazard... maybe even an explosion hazard on a gasoline generator.
> 
> Just removed the cover from my panel. Both bus bars (ground and neutral?) are physically tied together. If I'm right that those are G and N bus bars, they're both at ground potential.
> 
> While I understand electricity fairly well, I'm not sure why having ground and neutral bonded in two places (generator and bus bar) is an issue. They're both at the same potential.
> 
> I'm not saying it's not a problem - I apparently don't understand some things here - I'm just not seeing the issue.


well what you've basically got now is a ground and a neutral connected together at two ends, some of the current naturally will travel along the ground wire, this will cause the gfci on the generator to trip.


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## tjnoff

andrew79 said:


> well what you've basically got now is a ground and a neutral connected together at two ends, some of the current naturally will travel along the ground wire, this will cause the gfci on the generator to trip.


OK, that's making a bit more sense. By the two 30A breakers on the 240V outlet of the generator are basically GFCI breakers. So, just being bonded at one end (at the generator) doesn't allow that to happen.

It sounds to me like the best solution is to not connect the generator ground to the panel bus bar, but to ground the generator itself outside, per the owner's manual.


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## AllanJ

If you use an ungrounded extension cord (or unhook the green wire from the male receptacle on the side of the house) you eliminate the duplicate return path from the house panel via the ground wire and permanently bonded neutral and ground in the generator and thus prevent the generator GFCI from tripping under otherwise normal operation.

The generator GFCI will still protect persons from electrocution from generator power because the generator neutral is the ultimate return destination and the generator hot and neutral are monitored by the GFCI.

With an interlock transfer (any kind) set for utility power, there is no current flowing on the generator line to the house so there would not be a voltage drop on the neutral. In turn there could not be a floating above zero volts of the generator body still bonded to that neutral. (Zero volts relative to the other end of the generator neutral which is at the neutral bus and connection to the grounding electrode conductor.)


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## tjnoff

AllanJ said:


> If you use an ungrounded extension cord (or unhook the green wire from the male receptacle on the side of the house) you eliminate the duplicate return path from the house panel via the ground wire and permanently bonded neutral and ground in the generator and thus prevent the generator GFCI from tripping under otherwise normal operation.
> 
> The generator GFCI will still protect persons from electrocution from generator power because the generator neutral is the ultimate return destination and the generator hot and neutral are monitored by the GFCI.
> 
> With an interlock transfer (any kind) set for utility power, there is no current flowing on the generator line to the house so there would not be a voltage drop on the neutral. In turn there could not be a floating above zero volts of the generator body still bonded to that neutral. (Zero volts relative to the other end of the generator neutral which is at the neutral bus and connection to the grounding electrode conductor.)


Yes, I see that. I was somewhat confused by the term "extension cord." I was picturing an extension cord like you might use to use a drill away from an outlet in your house. 

I'll be using the 240V 30A NEMA L14-30 outlet on the generator, and, therefore, a heavy, 4-conductor cable (L14-30P - L14-30 R) from the generator to a L14-30P inlet box, then wire the inlet box to either a transfer switch or to two 30A backfeed breakers in the main panel (if I opt to use an interlock on the panel).

In either event, I won't connect the ground line from the generator to the transfer switch or the main panel... just let it float.

So, again, my remaining question: Should I physically ground the generator (to a grounding rod or some such) as specified in the owner's manual? I'm assuming that I should.

Thanks again!


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## wiz561

Hi!

I'm going through the same exact thing as tjnoff is. I have a Champion 7000/9000w generator and I bought a "generator inlet" box that I mounted outside. I have that wired to my main panel and have a 30 amp 2 pole breaker. On the generator, I purchased a 240v L14-30 4 conductor cable that I plug into the generator and then into the inlet. From what I read, it's a white, ground, and two hots on the inlet and outlet on generator. Nothing else is connected to the generator. No ground, nothing for the 120v outlets, nada. 

I assumed everything is grounded through the panel and sent to the generator via the ground in the cable. I want to do it the right way and that's why I'm asking. 


Thanks!


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## tjnoff

wiz561 said:


> Hi!
> 
> I'm going through the same exact thing as tjnoff is. I have a Champion 7000/9000w generator and I bought a "generator inlet" box that I mounted outside. I have that wired to my main panel and have a 30 amp 2 pole breaker. On the generator, I purchased a 240v L14-30 4 conductor cable that I plug into the generator and then into the inlet. From what I read, it's a white, ground, and two hots on the inlet and outlet on generator. Nothing else is connected to the generator. No ground, nothing for the 120v outlets, nada.
> 
> I assumed everything is grounded through the panel and sent to the generator via the ground in the cable. I want to do it the right way and that's why I'm asking.
> 
> 
> Thanks!


There was a further discussion of this here: http://www.diychatroom.com/f18/disc...portable-generators-148672/index3/#post957825

The consensus was that the best solution for wiring a portable generator to your main power panel (where neutral and ground are bonded together) was to run all four conductors (both hots, neutral and ground) from the generator through the inlet box to the power panel, and connect both neutral and ground to the panel's bus bar, but _only if_ ground and neutral are UNbonded on the generator. This is probably a couple of wires in the actual generator part of your portable generator.

Also, were you ever to use your generator stand-alone, to power tools in the field, for instance, you MUST rebond neutral and ground on the generator.


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## wiz561

Thanks for the shortened version. I didn't check the link, but in a short and sweet answer, what could happen if you don't unbound the neutral and ground on the generator?

Also, what happens in situations where the ground is to the EMT conduit? It doesn't get grounded to the bus bar through a cable, however, the neutral is grounded, as far as I know. So, essentially, the ground goes to the EMT which is grounded to the neutral....

Confusing stuff.

Thanks again for the short and sweet version!


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## andrew79

your ground could potentially carry some current.


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## stickboy1375

andrew79 said:


> your ground could potentially carry some current.


Being that it's the same size, it will carry half the current.


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## AllanJ

It is my belief that nothing bad will happen if the generator cannot easily have neutral and ground unbonded (and that step/process/instruction/mandate was therefore omitted/skipped/neglected) and also the panel was not revamped to separate grounds and neutrals, whether or not the ground connection (equipment grounding conductor) between the generator and panel is a metal conduit or a wire.

It would be a good idea to check the link to that other thread on proper grounding and reading the entirety thereof.


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## wiz561

*Thanks!*

Thanks for the information. I will definitely check out the other thread and read up. 

Thanks!


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## graydogg51

tjnoff said:


> There was a further discussion of this here: http://www.diychatroom.com/f18/disc...portable-generators-148672/index3/#post957825
> 
> The consensus was that the best solution for wiring a portable generator to your main power panel (where neutral and ground are bonded together) was to run all four conductors (both hots, neutral and ground) from the generator through the inlet box to the power panel, and connect both neutral and ground to the panel's bus bar, but _only if_ ground and neutral are UNbonded on the generator. This is probably a couple of wires in the actual generator part of your portable generator.
> 
> Also, were you ever to use your generator stand-alone, to power tools in the field, for instance, you MUST rebond neutral and ground on the generator.


I have an almost identical situation so this helps, but I have a question about the power inlet box itself.

I have the back feed breaker installed in my main breaker panel box now and the interlock kit to prevent the main and gen breaker from operating concurrently (I got tired of my transfer switch always being a few breakers short and didnt want to pay to upgrade to another transfer switch). My Honda generator previously had the neutral and ground bonded, but fortunately honda provides supplemental instructions on unbonding them and applying a sticker to warn they are now unbonded. I have already removed the bond, because my previous GenTran transfer switch required it to prevent the GFCI from tripping at the generator.

It's my understanding from the previous discussions that with an unbonded generator, and a bonded main panel that I should continue the ground connection through the generator power cord and then wire a ground from the power inlet (along with the other three wires) all the way to my main panel and tie it into the ground bus bar on the panelboard (which is bonded to the nuetral bar there via the little connecting bar and screw).

Finally, my question is in regards to the power inlet box itself (L14-30). When I remove it from the cover it already has a green ground wire coming from the back of the 4 prong inlet and is tied into the power inlet box cover plate via a screw. Do I remove this already supplied green ground wire from the power inlet box and run the seperate ground wire to the main panel, or do I leave it there and also install the ground wire to the main panel. It seems in that case it would be grounded at the power inlet box and at the main panel. Which way is the proper way?

1. remove the supplied ground wire attached to the power inlet frame and the g slot of the inlet connection and have the ground wire to the main panel connection ONLY?
2. Keep the short ground wire attached to the power inlet box frame and install the second ground wire to the main panel, having two ground wires connected to the G slot of the inlet connection?


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## Auger01

You definatly want the inlet box to be grounded! There are several ways to do this. You could just bring the ground wire from the main panel and terminate it on the ground screw along with the one going to the inlet. Another way would be to bring the ground wire from the panel and use a wirenut to join it with one wire going to the ground screw and another to the inlet itself. If you used metal conduit to connect the box to the panel, I dont believe a ground wire is required at all because the conduit serves as the ground conductor.

P.S. The inlet is only rated for one wire per connector. Puting two wires in the G slot would be "double lugging" and is a big no-no.


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## AllanJ

Auger01 said:


> ... bring the ground wire from the panel and use a wirenut to join it with one short length of wire going to the ground screw and another to the inlet itself...


Do it this way if two wires want to go under one screw or if one wire wants to go under two screws.


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## Kpack

*Bonded gen*



stickboy1375 said:


> If you cannot remove the N-G bond at the generator, then you must switch the grounded connector at the transfer switch.


I have a bobcat 225 welder woul like to use in emergency is there a way i could break into where neutral is grounded at frame with some sort of toggle switch for on or off for bond and neutral so when I used for home backup I would turn off and when I'm using welder and generator to work with I could turn the bond back on thanks


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## stickboy1375

Kpack said:


> I have a bobcat 225 welder woul like to use in emergency is there a way i could break into where neutral is grounded at frame with some sort of toggle switch for on or off for bond and neutral so when I used for home backup I would turn off and when I'm using welder and generator to work with I could turn the bond back on thanks


Personally, i would keep the internal bonds in tact, statistically, this is a safer mode of operation.


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## Kpack

*Bonds*

Well I like that idea but if i use square d homeline interlock breaker and back feed I would be bonded on both ends The other thought that I have come up with is a sub panel move only breakers i need and take neutrals and grounds that go with those circuits in the sub panel they would be a separate ground bar the feed for the sub would be 50 amp inlet male plug. main panel feed for sub would be 50 amp female plug if I wanted to use generator the plug would be unplugged from main to sub and plug there to the feed the sub from generator that plug would be my transfer switch when using gen I could stay bonded and totally of main. If I use the back feed method with interlock and stayed bonded in main and at generator what are my potentional dangers that way thank you


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## AllanJ

Kpack said:


> If I use the back feed method with interlock and stayed bonded in main and at generator then what are my potentional dangers that way thank you


Now I believe there are none.

If you can get an interlock compatible for back feeding the panel via a breaker set then you might not want to go through the trouble of installing a subpanel and rearranging into a group the circuits that will receive generator power.


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## andrew79

Kpack said:


> Well I like that idea but if i use square d homeline interlock breaker and back feed I would be bonded on both ends The other thought that I have come up with is a sub panel move only breakers i need and take neutrals and grounds that go with those circuits in the sub panel they would be a separate ground bar the feed for the sub would be 50 amp inlet male plug. main panel feed for sub would be 50 amp female plug if I wanted to use generator the plug would be unplugged from main to sub and plug there to the feed the sub from generator that plug would be my transfer switch when using gen I could stay bonded and totally of main. If I use the back feed method with interlock and stayed bonded in main and at generator what are my potentional dangers that way thank you


if your going to install a new panel then why not just use one of these
http://www.homedepot.ca/webapp/wcs/...1193&catalogId=10051&langId=-15&storeId=10051

keeps everything neat and tidy and you can fit 12 slim lines in them which is usually more than enough for most people.


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## Wayfarersun

I am very interested here but still don't quite understand. It seems several electricians have differing opinions on the neutral/ground in this thread. Or maybe you don't and it's I that don't follow.


I too am using an interlock kit on a 1983 SquareD QO Panel and am installing a standard 2 pole 30 amp breaker to serve as the backfeed breaker. 


1) Is a standard breaker is sufficient as long as it is secured by the bracket provided by the kit?


2) My panel seems to have one neutarl/gound bar and both the bare wires and neutrals are connected there. Must I also connect both the ground and neutral from the 10-3 wire that runs from the outside inlet box to the backfeed breaker to that bar?


3) Should I unbond the ground in the generator or leave the green wire disconnected as stated above somewhere between the generator and the panel?


Thanks
Mike


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## tjnoff

Wayfarersun said:


> I am very interested here but still don't quite understand. It seems several electricians have differing opinions on the neutral/ground in this thread. Or maybe you don't and it's I that don't follow.


No, you're right, there are differing opinions on bonding/unbonding N-G at the generator in this thread. 



> I too am using an interlock kit on a 1983 SquareD QO Panel and am installing a standard 2 pole 30 amp breaker to serve as the backfeed breaker.
> 
> 
> 1) Is a standard breaker is sufficient as long as it is secured by the bracket provided by the kit?


Yes, that's what I used and it tested fine.



> 2) My panel seems to have one neutarl/gound bar and both the bare wires and neutrals are connected there. Must I also connect both the ground and neutral from the 10-3 wire that runs from the outside inlet box to the backfeed breaker to that bar?


I did, but I know this is a point of discussion here (see my next answer). But, again, I tested the system and ran the fridge, lights, TV, etc. All ran fine.



> 3) Should I unbond the ground in the generator or leave the green wire disconnected as stated above somewhere between the generator and the panel?


Based on all of the very good input I got here on both sides of the discussion, I had the generator's N-G unbonded and the neutral and ground lines connected from the generator all the way through the inlet connection to the neutral bus bar in the power panel when I went to test this setup, but nothing in the house was getting power. I reconnected the N-G bond in the generator, left the neutral and ground lines connected between the generator and the bus bar, and everything in the house that I tested powered up.

I know there is still the open point about possible current on the ground line with neutral and ground bonded at two points, so I can't say it's 100% without risk, but others here have claimed to do it this way without issue. You'll just have to weigh the pros and cons for yourself as I did.


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## Wayfarersun

Thanks TJ,

For confirming it's an issue still under debate.  I will then connect the neutral and ground from the generator to the neutral bar in my panel. Course I've read enuff that somethings definitely work but remain with a potential for a problem even if the odds of a problem are negligible.

Can I double up the connects to the bar as ther are no open slots and I see that some slots are doubled up while some have only a single white or bare wire in a slot.

And thanks for confirming the standard 30 amp breaker is fine cuz I read only once in a forum that a standard breaker will trip or overload (or something to that effect). I think the only difference between the std and the special generator B/F Breaker is the special breaker has screws to secure it instead of the retaining clip one would use for the standard breaker.

Going to call Champion's hotline on their opinion and warranty. I noticed they have technical bulletins about unbonding at the generator.

I don't know alot about electricity but seems odd that the gen would not power your circuits with the ground unbonded.

Thanks again
Mike


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## tjnoff

As long as your leads have good physical contact when secured to the bus bar, it should be fine doubled up, although mine had space for extra connections, so I had no need to double any up.

My interlock kit came with a zip tie to physically secure the feedback breaker to the adjacent breaker in the other row. Other than that, it's just a standard dual-pole 30A breaker. 

Not sure why I didn't get power with the N-G unbonded at the generator, but as soon as I bonded it, I had power.


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## Wayfarersun

Perfect. 

Did you find kits for less than the $150 on InterLockKit.com? Price is pretty steep for two plates, a retainer and stickers. Does look like soimething that can be homemade.

Price wise when you add up the cost of the kit, backfeed breaker, piggyback breakers, inlet and generator cord; it's not a big savings over the 10 circuit transfer switch KIT at Home Depot. Though the flexibility to use any circuit with the interlock is nice as long as you don't over load the Gen.

Thanks once again!


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## AllanJ

tjnoff said:


> N-G unbonded at the generator, but as soon as I rebonded it, I had power.


Was unbonding neutral and ground in the generator as you did it according to the generator instructions?

Maybe you were not supposed to unbond N-G in the generator, and the generator center taps and other neutral related conductors were fundamentally connected to the frame with the neutral conductor to the receptacles also connected to the frame.


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## wiz561

*info*

Wow, lots of stuff still happening in this thread.

First question, what Champion generator did you get? I have the 7000/9000 watt one, and I believe that I read somewhere that the N-G is unbonded at the generator from the factory. I forget where I read it, but I thought I read it somewhere. 

What I did, and I should preface this with I am **NOT** an electrician, I just try to research and read up on these things. I bought an 'inlet' from Lowes and used a normal 30-amp double pole breaker in the box. I think I ended up running four cables; two hot for 240v and a neutral, then another one that's ground. I think I connected the ground to the grounding terminal in the breaker box. 

I ended up getting my interlock kit from Menards. That was the cheapest place I could find for one of these. For the Square D homeline one, it was like 50 bucks. 

Hope this helps!


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## tjnoff

Wayfarersun said:


> Perfect.
> 
> Did you find kits for less than the $150 on InterLockKit.com? Price is pretty steep for two plates, a retainer and stickers. Does look like soimething that can be homemade.
> 
> Price wise when you add up the cost of the kit, backfeed breaker, piggyback breakers, inlet and generator cord; it's not a big savings over the 10 circuit transfer switch KIT at Home Depot. Though the flexibility to use any circuit with the interlock is nice as long as you don't over load the Gen.
> 
> Thanks once again!


I bought the kit from Interlockkit.com, but over the phone. Their ecommerce site was NOT SSL encrypted when I went to buy it online (wasn't an HTTPS URL). Pointed that out to the guy on the phone. He said they were awaiting an encryption certificate. I told him he shouldn't have the site up without it. Allowing customers to provide credit card info without encryption is really dumb! Don't buy from them online if they haven't fixed that yet.

Nonetheless, it is a well-made interlock, although still over-priced. Machined billet metal plates, bolts with sleeved nuts for the plate to slide up and down on, Locktite for the bolts, strap for the back feed breaker, drill bit, etc. If you have a machine shop and the know-how and materials, make your own. 

And, yes, you could do a transfer switch for the same price, but as you point out, you lose the flexibility of powering any circuit you want. Plus the wiring is more tedious with the transfer switch. 

I created and posted next to the power panel a chart of precisely what each breaker in my panel feeds. Ceiling lights, outlets, fridge, TV, etc., and marked each one with green (OK to use on generator) or red (not OK, such as AC, oven, etc.). I also have posted a chart of how much current appliances in a home typically draw. 

I also have a dual gauge power meter mounted in the wall by the inlet plug and power panel that shows the current used in each of the two feeds from the generator. And there is the LED power gauge on the generator itself.


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## tjnoff

AllanJ said:


> Was unbonding neutral and ground in the generator as you did it according to the generator instructions?
> 
> Maybe you were not supposed to unbond N-G in the generator, and the generator center taps and other neutral related conductors were fundamentally connected to the frame with the neutral conductor to the receptacles also connected to the frame.


Well, the only mention in the manual about how/where neutral and ground are bonded in the generator was a drawing with a warning to ensure that the bond was connected after getting the generator serviced. Sure, there could also be bonds through the outlets, but I had no documentation for that, and I wasn't going to tear the generator apart with exploratory surgery. :no:

Unbonding at the generator was what was recommended in this thread, so that's what I tried. When I got no juice to the house, I knew that was the only thing I had done that might cause an issue, so I shut down, bonded N-G, started back up, and stuff worked! :thumbup:


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## AllanJ

tjnoff said:


> I wasn't going to tear the generator apart with exploratory surgery. :


I am so glad that you did not.

Doing that is not recommended.


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## Wayfarersun

Thanks for the info and tips.

I have the Champion Model 41532 7000/9000W made specifically for Costco.

I think if you have a relatively recent Square D panel that SquareD makes Interlocks in th 50-60 bucks range. My SquareD is about 30 years old and I can only find 2 sites that make what I beleive are aftermarket kits in the $150 bucks range. One site is the one everyone quotes, IntrerLockKit.com.

So far I've concluded to leave the neutral/ground bonded at the Gen (I'll try it unbonded too) and connect all four wires of the 10-3 wire from the inlet to the panel. I'll connect the neutral and ground wires to my common neutral/ground bar in the panel since it seems, even if not perfect, that this will work and the potential for risk is so minimal or in reality none, at least when using the GEN as a solely dedicated power source to the house. AS a stand alone gen i would bond N and G.

What ever I do. I'll label the house panel and gen with respect to the status of neutral and ground, even if just to remind myself.

So even though the I/L kit is overpriced I still like the flexibility it provides over the transfer switch and I think its a great idea to mark the breakers to be used in GEN mode including a corresponding chart of running and start up watts.

I think I'll stay away from homemade locks with hopes that the UL "tested" (as opposed to UL "listed") still avoids any liability should anything happen which I don't foresee since no will remove the breaker panel cover and the main and gen breakers can't be in the On position concurrently with the interlock. I've read both transfer switches and interlock kits are covered in the NEC code.

Thanks


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## Wayfarersun

Two other questions:

If the neutral and ground wire from the outside generator inlet box are connected to the neutral/ground bus in the breaker panel box, does that mean that a running generator is sending current into the house circuits via their neutral/ground legs as well as the hot legs? Or does it not matter because that is how Alternating Current works anyway? Or am I just not making sense?

And can the Gen send electricity back to the utility pole via the backfeed breaker which is connected to the neutral/gound bar which I beleive is also connected to the heavy ground cable coming from the utility pole (and the house grounding rod??), and does that pose a potential danger to the linemen? Or is that not a danger simply because it is the ground? Or am I just not making sense again or going in cicles?

Sorry if I am wasting time due to my own ignorance or confusion about electrical theory. :confused1:


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## AllanJ

Nothing is being setn back to the utility power lines when a properly connected transfer switch or interlock is set to generator power, even if the neutral remains connected to the utility lines.

Two conductors are needed to complete a circuit and establish a current flow. The transfer swtich or interlock disconnects all the hot lines so only one line, the neutral, remains connected to the utility feed.

When a generator is being used, hot from the generator to the panel hot bus or individual circuit/feed, and neutral back to the generator from the panel neutral bus are the two needed conductors for any 120 volt branch circuit. Downstream from the panel through any branch circuit or subpanel feed, ground and neutral are not supposed to be bonded so no current will flow on the ground wires that far.


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## wiz561

Wayfarersun said:


> Thanks for the info and tips.
> I have the Champion Model 41532 7000/9000W made specifically for Costco.


I've got that same one too. I don't want to stray away too much from the topic, but have you thought about converting it to NG (natural gas)? I've been thinking about it since finding gas in power outages is fun. If you are thinking about the conversion, PM me. The other thing I'd like to do is build a sound box for it...one of these days.


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## Wayfarersun

AllanJ: that makes sense now the way you layed out the circuits. Easier to visualise with confidence once an expert describes it.

Wiz: Just got the Gen, so dealing with conections-How-To at the moment, but I've given thought to alternate fuel since we almost ran out of gas locally with the majority of Conn. out of power and everyone running GEN's. Plus close enough to NY that they were coming to CT to get gas.

I though you needed a tri fuel GEN but then I thought I saw a conversion kit.

I'll definitely catch up via PM with you. I'm thinking of a sound barrier but saw one video that supposedly proved it's more about the muffler.

You guys have all been great with me coming in so late on this.

Thx
'


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## wiz561

For some reason, I can't send you a PM. I started another thread here that talks about the generator...

http://www.diychatroom.com/f2/champion-7000-9000-watt-costco-generator-164511/


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## bsmith1013

*Caution on N/G bonded at both gen and panel*

Recently installed a Square D interlock with a reliance inlet 30amp using 10/3. Hooked everything up and powered up gen and noticed sparking in my panel box. Unhooked the N/G bond on my generator and everything worked fine. Only conclusion I can make, is running a N/G bonded in two places is causing the ground to carry a current and has to be very dangerous. In my opinion you should never hook a bonded generator up to a panel.


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## AllanJ

bsmith1013 said:


> Recently installed a Square D interlock with a reliance inlet 30amp using 10/3. Hooked everything up and powered up gen and noticed sparking in my panel box. Unhooked the N/G bond on my generator and everything worked fine. Only conclusion I can make, is running a N/G bonded in two places is causing the ground to carry a current and has to be very dangerous. In my opinion you should never hook a bonded generator up to a panel.


Check for loose connections, screws,a nd setscrews, particularly on the neutral and ground busses of your panel, as a separate topic to that of bonding neutral and ground.


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## martym.

Wayfarersun said:


> Perfect.
> 
> Did you find kits for less than the $150 on InterLockKit.com? Price is pretty steep for two plates, a retainer and stickers. Does look like soimething that can be homemade.
> 
> Price wise when you add up the cost of the kit, backfeed breaker, piggyback breakers, inlet and generator cord; it's not a big savings over the 10 circuit transfer switch KIT at Home Depot. Though the flexibility to use any circuit with the interlock is nice as long as you don't over load the Gen.
> 
> Thanks once again!


 Check this out they range from $24 to $60. They might have one that will work for you.
http://w3.usa.siemens.com/us/internet-dms/btlv/residential/residential-murray/docs/Standby_Power_Interlock_Kits_Brochure.pdf​


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## mikegp

So general consensus is that if you're using an interlock and backfed breaker you should either buy a generator with no neutral/ground bond or remove the bond yourself?


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## rrolleston

The generac generator I bought showed how to remove the N G jumper. And If i use the generator somewhere else I can just reinstall the jumper.


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## mikegp

Do generators usually list that info somewhere? It would be nice while shopping for one if they mentioned if it was bonded and if it was easily removable.


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## rrolleston

mikegp said:


> Do generators usually list that info somewhere? It would be nice while shopping for one if they mentioned if it was bonded and if it was easily removable.


Not sure but getting a copy of the manual to check it out would be a good idea.


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## mikegp

I know, but as it is just narrowing down the 100's of choices is a chore. 

What gen did you get?


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## Dave88LX

This thread _literally_ just gave me a headache.


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## IslandGuy

stickboy1375 said:


> I know i stirred the pot on the issue, but the reality of it is, everyday generators are installed incorrectly by licensed contractors, and the like... Most people don't feel it is a real issue with the multiple N-G connection in a portable generator installation, well, because it still works in the end, and most likely will never be an issue. but still a violation none the less, and under the right circumstances could create a serious issue. Its one of those items that just gets installed either by lack of knowledge, or just the way we do it mentality...


 As was stated, most generators were meant to power portable tools via extention cords, and not built to meet NEC codes. That said: Portable generators can and are used to backfeed homes during power outages. Thousands, if not millions of people have done this without incident. During Sandy the entire neighborhood was running generators, I was running my house plus cords to 3 neighbors. We were out for 15 days. Everyone survived. Under the right set of unfortunate circumstances, someone can get hurt. What in life can't you say that about? Although removing the ground/neutral jumper in a generator "officially" voids the warranty, what generator offers anything over a year anyway? And should your generator require warranty service, do you really think the mechanic at the shop is going to tell the manufacturer not to cover the repair because it's been tampered with? If you DID disconnect the neutral / ground bond jumper, just replace it before dropping it off for repairs. As for the NEC... if I can unplug the thing and put it in the back of the pickup, it's portable utilization equipment. As long as my neutral and ground are separate up to the outdoor twistlock input I'm golden, what I temporarily plug into it is out of their jurisdiction as it's not permanently connected.


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## EFTHIM

With regards to bonding, can't you wire to sub panel? Sub panel has g n not bonded. Wouldn't that eliminate issue with g-n at generator? Use sub panel specifically as generator panel?


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## Oso954

No, you still have 2 neutral/ground bonds (1 at main panel, 1 at generator). You either need a transfer switch that will switch the neutral to the main panel out, or break the bond at the generator.


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## Toller

stickboy1375 said:


> The only way you can use a interlock kit legally is if his generator has a floating neutral. Otherwise, he would need a manual 3 pole transfer switch.


That's true, but all generators made for home use have floating neutrals.


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## patmurphey

Toller said:


> That's true, but all generators made for home use have floating neutrals.


 Not true for portable generators. Some do, some don't. Some that have bonded neutrals specifically give the option of removing a jumper.


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## Vrod1130

Great information. My generator says it has a system ground that connects the cram to the ground terminals in the Ac recepticals The system ground is not connected to the Ac neutral wire. 

So do I need to disconnect the ground at the generator if I connect the ground and the neutral to the buss bar in my panel?


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