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This generator neutral bond to frame thing is driving me nuts

This generator neutral bond to frame thing is driving me nuts

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  #1  
Old 11-30-11, 03:02 PM
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This generator neutral bond to frame thing is driving me nuts

I had in another thread asked about this and got some good info, but it seems like the further down the rabbit hole I go it gets worse.
I want to hook my new Generac GP7500e to my home via the 240 plug and cord, inlet box, back feed breaker and interlock kit. The manual says the neutral is bonded to the frame. The inlet box is wired to the home load center and grounded there along with the neutral going to the neutral bar in the home load center. Everything I have read and was told is that I can't have it bonded at the home panel and leave the neutral bonded to frame on the generator. However when I read a lot of that, it seems to pertain to GFCI outlets on the genset. I don't have GFCI outlets on my gen model, just the standard circuit breakers for each duplex outlet and 240 outlet. I have read that at least on other or previous Generac models you can simply removed the neutral to ground bond jumper wire behind the panel. However, I was lucky enough to purchase the one they don't make in Wisconsin but our friends overseas. My manual does not have a wiring diagram to identify the jumper, nor can I seem to easily identify it in the mangle of wires behind the panel.
Any suggestions on this or links of wisdom would be great.
 
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  #2  
Old 11-30-11, 03:06 PM
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I did call Generac for help. They kindly put me on hold and referred me to a "local" service tech as that is who they use for tech support on the consumer side. The number they gave me promptly lead me to an answering machine saying the PA tax office would be closed for Christmas.......
 
  #3  
Old 11-30-11, 05:12 PM
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Keep calling. The squeaky wheel gets the grease!

At least you have an English speaking company to call. Many things made in China have no documentation and no number to call nor a web site. If you need support, too bad! (Why I am avoiding buying anything made in China anymore...)
 
  #4  
Old 11-30-11, 05:56 PM
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Quite simply, there is NO code-approved method of connecting a portable generator (one with receptacles) to a premises.

If you have a "grounded" conductor, i.e. a "neutral" at the generator then the equipment grounding conductor in the interconnecting cable (from the generator to the service panel) becomes a "parallel path" for return current.

If you have a dual voltage generator The "neutral point" MUST be bonded to the equipment ground or a hazardous condition could exist under fault conditions. This bond MUST take place BEFORE the first disconnect AND no other such bonds allowed. That eliminates the use of mechanical interlocks on panels that do not simultaneously switch the neutral conductor.

The only work-around, and it is NOT code compliant, is to remove the equipment grounding conductor between the generator and the service panel and this method introduces other hazards.
 
  #5  
Old 11-30-11, 06:17 PM
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This confuses me. Why do they sell the inlet boxes and transfer switches then if there is no code compliant way to hook a portable gen to a home panel?



Originally Posted by Furd View Post
Quite simply, there is NO code-approved method of connecting a portable generator (one with receptacles) to a premises.

If you have a "grounded" conductor, i.e. a "neutral" at the generator then the equipment grounding conductor in the interconnecting cable (from the generator to the service panel) becomes a "parallel path" for return current.

If you have a dual voltage generator The "neutral point" MUST be bonded to the equipment ground or a hazardous condition could exist under fault conditions. This bond MUST take place BEFORE the first disconnect AND no other such bonds allowed. That eliminates the use of mechanical interlocks on panels that do not simultaneously switch the neutral conductor.

The only work-around, and it is NOT code compliant, is to remove the equipment grounding conductor between the generator and the service panel and this method introduces other hazards.
 
  #6  
Old 11-30-11, 06:46 PM
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Good question and all I can offer is a mediocre answer.

The NEC (National Electrical Code) is no different than any other model building code in that it has no enforcement powers. Codes are nothing more than advisory UNTIL enacted into law by a political subdivision such as a state legislature or a county or city council. These political subdivisions have the right/power to add to or delete from the model code although such additions and deletions are usually fairly minor. Bottom line is that it matters little what the national (model) codes state, you only need to comply with the codes as they are enacted into law in your area.

Since the model codes are only advisory they have no power over what is manufactured or sold. The enabling legislation at the state, regional or local level could include bans on the sale of "non-approved" items but such is extremely rare. The purchaser is left to their own ignorance and the ignorance of the retail sellers as to whether or not any particular item will be acceptable to the inspection agency. What's worse is that some of these inspection agencies are quite remiss in stating what IS and IS NOT acceptable.

Lastly, it has only been with this last code cycle that the NEC has made so many restrictions on the connections of portable generators.

It is incumbent upon the homeowner/installer to determine the hazards of various means of connections and to make the determination of what hazards they are willing to accept. This will, of course, be tempered by local codes, inspections and perhaps most importantly, individual insurance companies.
 
  #7  
Old 11-30-11, 07:02 PM
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That's a reasonable answer. Sort of reminds me of when I was pulled over when I was 16 because I had smoke out lens covers on the lights of my car. I was ticketed and my response was if they are illegal why do they sell them here. Officers response, drugs are sold here too, doesn't mean it's legal.....

Originally Posted by Furd View Post
Good question and all I can offer is a mediocre answer.

The NEC (National Electrical Code) is no different than any other model building code in that it has no enforcement powers. Codes are nothing more than advisory UNTIL enacted into law by a political subdivision such as a state legislature or a county or city council. These political subdivisions have the right/power to add to or delete from the model code although such additions and deletions are usually fairly minor. Bottom line is that it matters little what the national (model) codes state, you only need to comply with the codes as they are enacted into law in your area.

Since the model codes are only advisory they have no power over what is manufactured or sold. The enabling legislation at the state, regional or local level could include bans on the sale of "non-approved" items but such is extremely rare. The purchaser is left to their own ignorance and the ignorance of the retail sellers as to whether or not any particular item will be acceptable to the inspection agency. What's worse is that some of these inspection agencies are quite remiss in stating what IS and IS NOT acceptable.

Lastly, it has only been with this last code cycle that the NEC has made so many restrictions on the connections of portable generators.

It is incumbent upon the homeowner/installer to determine the hazards of various means of connections and to make the determination of what hazards they are willing to accept. This will, of course, be tempered by local codes, inspections and perhaps most importantly, individual insurance companies.
 
  #8  
Old 12-01-11, 10:13 AM
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3 wires instead of 4 ?

This was the first I read this on another site. In my application if I am unable to remove the generator neutral to ground bond, using the L14-30 plug into the inlet box on house, only connect three of the four wires ? The 2 hots and neutral from the gen, to the inlet box, to the home load center. That way the neutral is bonded to ground in only one place (at the home load center) and not two places such as gen and the load center? Does this make sense?
 
  #9  
Old 12-01-11, 10:36 AM
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Hummm...

Neutral bonded to ground at generator.
No GFCI on generator.
Non-neutral switching transfer switch (2 pole).

Then the question is if the ground to the generator could be left disconnected, but still connect the two hots and neutral to the transfer switch.

Then three questions follow...

Will this work? Yes!

Is this safe? Let's see... If the neutral connection was lost to the generator, then everything connected to ground in the house could become hot! (Like the metal frame on a range, refrigerator, washing machine, metal garage door, etc.) Even if these were not being powered by the generator.

Is this allowed by code? I'll leave that to the code gurus.

Would I do this? No! (I would use a neutral switching transfer switch and also connect the ground to the generator.)
 
  #10  
Old 12-01-11, 10:44 AM
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Ok, good to know. So basically my only options are to find this damn jumper wire on the gen or get the three way transfer switch ...
 
  #11  
Old 12-01-11, 12:18 PM
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Ok, hopefully this picture thing works. I think I found it. This is the back of my generator panel, more specific, the back of the 240 plug and one of the duplex outlets to the right of it. Is this small green ground wire (only one) going to the neutral line of the duplex outlet neutral the neutral bond to ground jumper they are talking about?? If I pull this small wire based on what I see, everything would be isolated correct? Grounds all seem to just be grouped with grounds, hots with hots, neutrals to neutrals etc... I hope this is it so I can finally hook this thing up to the home load center. This should "unbond" the neutral to ground on my generator correct?





[IMG] Uploaded with ImageShack.us[/IMG]
 
  #12  
Old 12-01-11, 12:35 PM
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If your generator outputs 230/120 volts, as evidenced by the four-wire L14-30 connection, then you are screwed, blued and tattooed as far as maintaining any semblance of a code approved connection using either a panel interlock or a non-neutral switching transfer switch or panel.

Under NO CIRCUMSTANCES should you remove the neutral-ground bond on a dual voltage generator. Doing so greatly increases the hazard of higher voltage due to a line-to-ground fault.

Having the neutral-(equipment) ground bond at both the generator AND the service panel creates a parallel path for return currents to flow on the equipment grounding conductor. This is actually TWO code violations.

Disconnecting the equipment grounding conductor of the interconnect cable between the generator and the house inlet connector is technically a code violation but is the next best to having a switched neutral as it at least removes the parallel path for the returning current. Understand that I DO NOT ADVOCATE NON CODE COMPLIANT CONNECTIONS.
 
  #13  
Old 12-01-11, 12:41 PM
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can you better explain how removing this jumper increases the hazard for line fault ? Doesn't this turn it into the same as a generator with the same set up but a "floating neutral' ?
 
  #14  
Old 12-01-11, 12:52 PM
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Give me an hour or two, I'm feeding my face.
 
  #15  
Old 12-01-11, 12:57 PM
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Copy. I appreciate the info. After reading some more, some of the gen documentation on other models similar to mine say to remove the jumper. It would have to be labeled as floating though so you knew it wasnt safe as a stand alone
 
  #16  
Old 12-01-11, 02:06 PM
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Some generator manufacturer's provide instructions for removing the bond and new labeling
to place on the generator.

I would only do this if you could get those written instructions from the generator manufacturer
as well as the label(s). Then you are covered!

If they say don't do that, then I would think it would be a good idea to follow their
advice. They are most familiar with the generator and problems it has experienced out in the field.
 

Last edited by Bill190; 12-01-11 at 02:25 PM.
  #17  
Old 12-01-11, 02:25 PM
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It's Generac, so they are of no help at all. If I call as a "consumer" they don't offer anything except the number to a local service tech. Generac won't even answer the simple question.......lawyers rule the world
 
  #18  
Old 12-01-11, 02:34 PM
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Thanks! I wouldn't recommend them if they are not going to provide customer support.

Might want to call or write to the big shots. See "Officers and directors" at the following link about 3/4 the way down the page...
Generac Holdings Inc.: NYSE:GNRC quotes & news - Google Finance
 

Last edited by Bill190; 12-01-11 at 05:29 PM.
  #19  
Old 12-01-11, 02:43 PM
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Good idea. Previous model owners did get info from them on how to remove the jumper. I did find a recent post from someone who has the GP8000 (I have the GP7500) and they told him it violates their UL rating if you remove it. So he asked for the schematic or wiring diagram and they told him no. Yet other Generac models have had their jumper removed for this application and no issues. Except since they did not provide the placard I think the owner placarded the gen themselves to state it was floated.
 
  #20  
Old 12-01-11, 03:07 PM
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Based on that picture does that look like the jumper I am looking for? On the other models the back of the panel was different and the jumper was easier to pick out. This is the only point I could see where the neutral lines and ground lines were together
 
  #21  
Old 12-01-11, 05:28 PM
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If the manufacturer says not to do this, then you are on very much your own!

No one will give you any support on modifications like this without written manufacturer approval
(electrical inspector, insurance company, OSHA, courts in case of accident, etc.).
 
  #22  
Old 12-01-11, 05:34 PM
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Yes I understand that part. The manufacturer is bound by litigation like much of the world. They not only have to comply with their UL rating but the lowest common situation. If I remove this bond, it makes it "dangerous" as a stand alone unit like on a job site or what ever. I understand that. I don't plan on using it that way, and if I do, would place the bond back in. If you could not do this on this gen due to any other reason they should state that. Even their home website has a Q&A section for every model they have so their staff can answer it. I am one of three that are asking the same question as to how to un-bond the gen. No answers yet....
If it was such an issue they could at least respond with some smoke up the ass answer like not possible on this gen due to design. The have answered how to start it if the battery is dead though...
 
  #23  
Old 12-01-11, 07:41 PM
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Having the "neutral" to ground bond at the source limits the voltage from a line to ground fault and facilitates the tripping of the overcurrent protective device at the generator. ALL "separately derived sources" use a neutral to ground bond when they output multiple voltages. The outputs of wye-connected utility generators have the bond, the secondaries of wye-connected transformers (of all sizes) have the neutral to ground bond, the secondaries of single-phase 240/120 volt transformers have the neutral to ground bond.

People much smarter than I have determined the neutral to ground bond AT THE SOURCE to be the safest and they have succeeded in having this written in the national code.

I can think of only one situation where this neutral to ground bond causes problems and that is when an additional neutral to ground bond exists downstream of the one at the source.

With the addition of an equipment grounding conductor (the green "ground wire) in the generator-to-service panel interconnect cable) the equipment grounding conductor becomes a parallel path for returning (neutral) currents, something the equipment grounding conductor is NOT designed to handle plus being a code prohibition in and of itself. It would seem simple enough to remove the equipment grounding conductor from the generator-to-service panel-interconnect cable but doing so would also remove the (required) low impedance path that facilitates the tripping of the generator's overcurrent protective device (OCPD) in case of a line-to-ground fault between the generator and the service panel. Some might argue that such a fault is uncommon but I won't. Furthermore, except in the case of a properly sized generator circuit breaker used in conjunction with service panel mechanical interlock, the generator's OCPD is THE main OCPD for the entire standby system.

Connecting a generator with a bonded neutral to a panel with a bonded neutral is the same as having a "sub-panel" with the equipment grounding bus connected to the neutral bus.

There is more if you need it.
 
  #24  
Old 12-02-11, 05:32 AM
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Thanks for the info Furd.

The problem I was told is that I am hooking this into a home panel that is also bonded with neutral so I would be having a second place bonded if I leave the generator bond in place giving that dual path back to the gen (which I think you mentioned).
 
  #25  
Old 12-02-11, 05:35 PM
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Furd,

Would unbonding the neutral and equipment ground at the generator and then connecting the equipment ground to it's own ground rod solve this problem?
 
  #26  
Old 12-02-11, 07:02 PM
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Originally Posted by drooplug View Post
Furd,

Would unbonding the neutral and equipment ground at the generator and then connecting the equipment ground to it's own ground rod solve this problem?
No. The connection to the earth is almost exclusively for protection from lightning.
 
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