Gen Backfeed with a Transfer switch possible?

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  #1  
Old 11-26-11, 11:06 PM
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Question Gen Backfeed with a Transfer switch possible?

Hi!, I'M Lewis, New to here as registered, but have read alot on this wonderful site many times!
Looking for some advice, input. ( my backround is in Electronics)
I have a Detached garage with a Sub panel 50 Amp.( # 4 wire) Its all to code with Isolated Neutral bar, and separate grounding bar, and 2 exterior 8 foot long Grounding rods in the ground. It has a 40 amp breaker, upper right, with an outlet outside for my 7,000 watt Generator. ( L14-30 4 prong). The purpose of this was to backfeed the house in the future.
WE tested this once, and since the Gen is Bonded, we used the "Separately derived system" and unhooked the Power company grounding wire ( neutral to some, in the Main) and shut off the main breaker. (This all worked well fyi)
I do not plan to use this "as is" and would like ideas on how a transfer switch might work ( near the Main) and still be able to power the Garage when the "Street" power is on. I would plan on leaving the Grounding unhooked in a 2 prong transfer switch if this is possible.
Thanks for any help!
 
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  #2  
Old 11-26-11, 11:36 PM
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All I can say is no, NO, NO! There are so many things wrong that I can't even list them.

IF you have conduit of sufficient size between the house and the garage you could, with a fair amount of work and additional materials, get a system working that would be safe and legal. What you have now is neither.
 
  #3  
Old 11-27-11, 01:49 AM
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Originally Posted by Furd View Post
All I can say is no, NO, NO! There are so many things wrong that I can't even list them.

IF you have conduit of sufficient size between the house and the garage you could, with a fair amount of work and additional materials, get a system working that would be safe and legal. What you have now is neither.
The Conduit is #4-3 which is sufficient, but I see you may be on a path to a separate wire, which puts it back to a standard Gen set up, which is what Ill do I guess...due to lack of Ideas.. anyone else ??
 
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Old 11-27-11, 06:47 AM
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The Conduit is #4-3 which is sufficient
Conduit is sized in inches, such as 2", 2 12/", 3", etc. You probably need a transfer switch and generator inlet near the main panel at the house to either power the entire house service including subpanels or to power a new small subpanel which could also contain the subfeed breaker to the garage. You should either remove the generator's bond between ground and neutral or purchase a 3 pole transfer switch which transfers the neutral and isolates the service neutral from the generator neutral. Never, NEVER disconnect the service ground from the service neutral.
 
  #5  
Old 11-27-11, 06:49 AM
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There is no way to legally backfeed the main panel through the garage panel. The generator would have to be connected directly to the main panel with an interlock switch; or connected to a transfer panel adjacent to the main. You can run a long cord from the generator so it can be located in the garage, but electrically it must connect to the main through an approved transfer switch or interlock.

You're proposing a dual-purpose feeder between the house and garage, used both for the garage panel and the generator. There is no way to make that work legally or safely.
 
  #6  
Old 11-27-11, 11:19 AM
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Originally Posted by Furd View Post
All I can say is no, NO, NO!
I agree!

I read the part about "unhooked the Power company grounding wire" (and other things) and said to myself... "YOU DID WHAT?"

Anyway NO NO NO!

Get a proper transfer switch, and electrical permit, and possibly the help of an electrician.
 
  #7  
Old 11-27-11, 03:12 PM
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Originally Posted by CasualJoe View Post
Conduit is sized in inches, such as 2", 2 12/", 3", etc. You probably need a transfer switch and generator inlet near the main panel at the house to either power the entire house service including subpanels or to power a new small subpanel which could also contain the subfeed breaker to the garage. You should either remove the generator's bond between ground and neutral or purchase a 3 pole transfer switch which transfers the neutral and isolates the service neutral from the generator neutral. Never, NEVER disconnect the service ground from the service neutral.
Using a 2 pole transfer with the neutral disconnected does the same thing, as discussed in other posts. I do undertsand your thoughts which is where it seems to be heading, Thanks!
 
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Old 11-27-11, 03:21 PM
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Originally Posted by Bill190 View Post
I agree!

I read the part about "unhooked the Power company grounding wire" (and other things) and said to myself... "YOU DID WHAT?"

Anyway NO NO NO!

Get a proper transfer switch, and electrical permit, and possibly the help of an electrician.
Ya know, just saying NO, is a bit small. I asked for ideas, has anyone done what i proposed, at least you could say , yes it can be done safely and it requires X and X , etc, a Electrician isnt a issue here, paying through the nose isnt even an issue. . I salute those with Ideas and willingness to engage the thought process. If we all said NO, we would have never made it to the Moon.
Ill get a transfer switch, and as I said in first post, since the Gen is Bonded, Ill leave the grounding open in the T switch, so there is absolutely NO link to the power company and put the outlet outside on the house. Ill get an electrician who can tell me that ALL the other electricians are wrong LOL ( this has happened already 2 times with electrical, just like the woodwork, and the plumbing!)
 
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Old 11-27-11, 03:25 PM
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Originally Posted by ibpooks View Post
There is no way to legally backfeed the main panel through the garage panel. The generator would have to be connected directly to the main panel with an interlock switch; or connected to a transfer panel adjacent to the main. You can run a long cord from the generator so it can be located in the garage, but electrically it must connect to the main through an approved transfer switch or interlock.

You're proposing a dual-purpose feeder between the house and garage, used both for the garage panel and the generator. There is no way to make that work legally or safely.
Thank you for a clear and concise answer! Thats all I really needed to hear!!
 
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Old 11-27-11, 03:27 PM
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Ontheborder, From my knowlege if you are going to use the gen for the home and will be plugged into the home what you want to do is unbond the gen. This is the easiest.

Hook everything back up in the panal the way it was. So what you go in your panal and disconnect and reconnect the bond everytime you use the gen or not use the gen?

Decide how you will feed the main panal. Transfer switch or interlock. Then take it from there.

The way you decsribe is not to code. If not following code there will be not much help here I can say.

Mike NJ
 
  #11  
Old 11-27-11, 03:39 PM
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Originally Posted by lawrosa View Post
Ontheborder, From my knowlege if you are going to use the gen for the home and will be plugged into the home what you want to do is unbond the gen. This is the easiest.

Hook everything back up in the panal the way it was. So what you go in your panal and disconnect and reconnect the bond everytime you use the gen or not use the gen?

Decide how you will feed the main panal. Transfer switch or interlock. Then take it from there.

The way you decsribe is not to code. If not following code there will be not much help here I can say.

Mike NJ
Thanks Mike! Yes I unhooked the Bond when we tested it for about 3 minutes. Its not a permanent set up, and I know its not Code and will never run it that way. After reading alot on here I found that its legal to leave the gen bonded and just unhook the bond in the transfer switch and cap it. This , with the transfer switch basically completely unhooks the gen from the power company making it a separately derived system.. which is the goal, correct? I cannot even find a 3 way Transfer switch and I was told this is new for 2011 code, the separately derived system.
So the garage dream is out... I want it to code and safe.. Thanks lawrosa!!
 
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Old 11-27-11, 04:17 PM
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Yes I unhooked the Bond when we tested it for about 3 minutes
Unhooked the bond from where?

After reading alot on here I found that its legal to leave the gen bonded and just unhook the bond in the transfer switch and cap it
I dont believe that is code. I believe the code is that the transfer switch itself has to have a neutral disconnect.


I think you should read this and educate your self somewhat.

http://159.105.83.167/Portals/0/WP%2...tandards22.pdf

And if you want a nuetral disconnect just search reliance.

Neutral switching panals.

X-Series Neutral Switching Panels | Products | Reliance Controls Corporation=

Mike NJ
 
  #13  
Old 11-27-11, 05:03 PM
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Merely removing the "neutral/equipment ground bond" in a portable generator is NOT the proper or code compliant method of connecting a generator to residential wiring that is also served via utility power.

There are several ways to connect a generator to a residence and ALL OF THEM HAVE SOME HAZARDS involved. Codes are designed to reduce the hazards but cannot eliminate all hazards. The latest version (2011) of the National Electrical Code has added several provisions that make portable generator connections to residential systems safer, but also introduce additional requirements.

It bothers me greatly when I see comments from people that are not electricians or electrical engineers giving information that is NOT code compliant. It is bad enough that many electricians don't understand the requirements without having lay people also giving out incorrect information.

That stated, many of the "problems" the latest code revision is trying to reduce are, in fact, unlikely under most circumstances. I would rather that people adhere to an earlier code and state up front that there ARE other hazards that can arise by using the earlier code provisions than try to state that their interpretation IS compliant.
 
  #14  
Old 11-27-11, 05:11 PM
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Google "Neutral switching transfer switch"

Then so far as disconnecting/connecting grounds and so forth. I have a BIG fear of doing this.

Under certain situations, malfunctioning appliances can be placing a hot voltage on a ground. So if a main ground is disconnected in some situations with your bare hands, you could be electrocuted.

Also even with your main power totally off, a hot voltage can be entering your electrical system from the electric company neutral wire via a neighbor's malfunctioning appliance. And you could be electrocuted while connecting or disconnecting a main ground wire.

And the other way around... A neighbors malfunctioning electric system could be placing a hot voltage on the city water pipe system. So if your ground wire is disconnected, there could be a difference in potential which could electrocute you.

The biggest danger is from one hand to the other hand and this goes through the heart.

"A domestic power supply voltage (110 or 230 V), 50 or 60 Hz alternating current (AC) through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60 mA..." From...
Electric shock - Wikipedia, the free encyclopedia

Anyway *assume* those ground wires are hot when you handle them. We don't want to see you "fibrillating"! Please be careful is all...
 
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Old 11-27-11, 06:14 PM
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Yeah Furd if your talking about me I should say I am not an electrician, but have studied the code regarding portable generators extensivley. This is in regards to grounding, bonding, gfi, etc.

I did this because I too got conflicting information from several electricians regarding portable generators, with regards to wiring my own. What I also found is some of the electricians here seem to give this conflicting information to individuals asking for correct info, and I am just passing on what I learned in wiring my portable generator for the home.

The link I found that describes it all in an easy to understand document is the link below. A union electrician friend turned me on to it. Its in plain laymans terms that are easy to understand.

If anyone thinks the below is incorrect let me know. I will shoot the OSHA trainer an e mail.


http://159.105.83.167/Portals/0/WP%2...tandards22.pdf

With that said, it also comes down to "following the code in your state and local jurisdiction".

Mike NJ.
 
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Old 11-27-11, 06:40 PM
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Mike, I wasn't referring to you specifically, you just happen to be the latest in a line of people that have been trying to help but unfortunately do not understand the whole picture. Heck, I have trouble understanding the entire thing and I've been working with electricity (and college educated about it) for my entire life.

I'll add this, when working with a single voltage (120) generator then having an UNgrounded system is quite safe. Both wires are "hot" and there is no neutral. Accidentally "grounding" one of the two wires will not cause any problems but MAY become hazardous under some conditions.

When the generator has a dual voltage (240/120) then having the "neutral" ungrounded can be quite hazardous.
 
  #17  
Old 11-27-11, 07:28 PM
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Have generators changed that much over the years. I use to have a old army generator, that was my father. It had this long brass rod, you needed to drive in the ground to work, or at least work right, with out getting shocked.
 
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Old 11-27-11, 07:37 PM
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It is not the generators themselves that have changed but the way they are connected, especially to residences. As "we" have learned more we have learned that there are specific methods that need to be followed to reduce the hazards.

IF there are no "other" hazardous conditions present, then connecting a generator without a "neutral-to-equipment ground bond" at the generator to the main power input while simultaneously disconnecting the "hot" leads from the utility is reasonably safe. The problems arise when there ARE other hazards involved and it is for these conditions that the code has been revised numerous times to the present requirements.
 
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Old 11-27-11, 08:12 PM
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Originally Posted by Edward074 View Post
Have generators changed that much over the years. I use to have a old army generator, that was my father. It had this long brass rod, you needed to drive in the ground to work, or at least work right, with out getting shocked.
Actually generators were quite easy to understand until they started putting GFCI's on them. THAT caused all sorts of problems and complications so far as using these for back-up power on a house!

Now there are terms like "neutral switching transfer switch", "separately derived system" and "non-separately derived system".

And then when your regular homeowner searches for those terms, they are likely to find information and complex wiring diagrams for commercial or industrial 3 phase systems.

But some of the generator manufacturers have posted some easier to understand diagrams and info on this. But it is still quite complex.
 
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Old 11-27-11, 08:35 PM
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When the generator has a dual voltage (240/120) then having the "neutral" ungrounded can be quite hazardous.
But would it be safe to say when you then plug that 120/240 gen to the home the gen becomes bonded because the neutral is bonded at the panal......It becomes a Nonseparately Derived System.

If you use that same gen and dont hook it to the home but plug things into its outlets it then it becomes a separately Derived System and the gen needs its own bond.

Grounding rods at the gen are not needed and only for lightning protection.....

What do you think? It all seems easy to understand IMO.

Mike NJ

 
  #21  
Old 11-27-11, 09:25 PM
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I don't why folks try to make things more complex than they need to be.

If you live in the northern states, some of the power companies will rent you a switch that mounts directly behind the meter and does everything you need it to do. All you have to do is manage the circuits that the generator can handle. If they don't offer it, you can buy one for a few hundred dollars and will have spent less than you will spend trying to wire it the hard way. I bought one years ago and never looked back.

And, I think 40 amp is too big for your generator anyway.
 
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Old 11-27-11, 10:49 PM
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switch that mounts directly behind the meter and does everything you need it to do. All you have to do is manage the circuits that the generator can handle.
http://www.electromn.com/pdf/LI112.pdf

Well not really. Its not all done for you.

don't why folks try to make things more complex than they need to be.
Every install is different and needs to be looked at on an individual bases.

Below is from the link above.

Grounding and Bonding


This transfer switch product is installed and wired on the service entrance side of the distribution panelsingle point grounding/neutral. In reality (and the safest approach) neutral and ground are the same pointthroughout this transfer switch product. As shown on hookup drawing LH112, page 2, use the followingguidelines:-

Temporary/Portable Generators1. A 4-wire system with the generator neutral isolated at the generator.2. Add a copper ground wire from the control box ground lug to the building groundstake/safety ground.-

Permanent Generators1. 4-wire hookup with the generator grounded at this control box case.2. The generator neutral is isolated at the generator.3. Generator neutral goes to isolated neutral block within this control box.4. Add a copper ground wire from the control box ground lug to the building ground

stake/safety ground.

Here is the main link to their products.

Semi-Automatic Generator Transfer

Mike NJ
 
  #23  
Old 11-28-11, 02:06 AM
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Originally Posted by lawrosa View Post
Unhooked the bond from where?



I dont believe that is code. I believe the code is that the transfer switch itself has to have a neutral disconnect.


I think you should read this and educate your self somewhat.

http://159.105.83.167/Portals/0/WP%2...tandards22.pdf

And if you want a nuetral disconnect just search reliance.

Neutral switching panals.

X-Series Neutral Switching Panels | Products | Reliance Controls Corporation=

Mike NJ
Thanks for the info! I have read previously the Osha article wich validates what I need. The other link, has a 3 way switch listed, but it seems its a panel, then says none found, I would love to see just a transfer switch with a neutral switch though...
"
The sequentially-switched neutral means you can switch between a portable generator and utility power without the danger of sending 240V current to a 120V circuit.

The New Reliance Panel/Link X Series is a double-pole manual transfer switch with an exclusive third-pole for the neutral that switches sequentially. The X Series is perfect for use with generators having GFCI protected outlets, bonded neutral generators and installations requiring a separately-derived system.

On GFI protected generators, the X Series will prevent a ground fault which will, in turn, prevent the circuit breakers on the generator from nuisance tripping.

The XRC Series has 10 branch circuit spaces and will allow up to 18 circuits with the use of tandem breakers. The XRR Series allows for 26/36 branch circuits and is available in indoor and outdoor enclosures. Options include a selection of watt meters, for balancing generator load, and flanged inlets for direct generator connection where permitted.

For use with:

* GFI-equipped generators
* Bonded neutral generators
* Separately-derived systems

Sorry - we were unable to find any Panel/Link X Series products
 
  #24  
Old 11-28-11, 02:15 AM
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Originally Posted by Furd View Post
Merely removing the "neutral/equipment ground bond" in a portable generator is NOT the proper or code compliant method of connecting a generator to residential wiring that is also served via utility power.
>> I never did that or suggested it <<

There are several ways to connect a generator to a residence and ALL OF THEM HAVE SOME HAZARDS involved. Codes are designed to reduce the hazards but cannot eliminate all hazards. The latest version (2011) of the National Electrical Code has added several provisions that make portable generator connections to residential systems safer, but also introduce additional requirements.

It bothers me greatly when I see comments from people that are not electricians or electrical engineers giving information that is NOT code compliant. It is bad enough that many electricians don't understand the requirements without having lay people also giving out incorrect information.

That stated, many of the "problems" the latest code revision is trying to reduce are, in fact, unlikely under most circumstances. I would rather that people adhere to an earlier code and state up front that there ARE other hazards that can arise by using the earlier code provisions than try to state that their interpretation IS compliant.
Im glad you spoke your mind on the latest revision, which seems to indicate a "Separately derived system" with a bonded generator is the way to go.
IT seems that interpreting the code is a science within itself. Im going to buy a new code book and see if I can learn more, so I know. I tend to agree with your statement on the old code . Thanks for posting!
 
  #25  
Old 11-28-11, 02:18 AM
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Originally Posted by Bill190 View Post
Google "Neutral switching transfer switch"

Then so far as disconnecting/connecting grounds and so forth. I have a BIG fear of doing this.

Under certain situations, malfunctioning appliances can be placing a hot voltage on a ground. So if a main ground is disconnected in some situations with your bare hands, you could be electrocuted.

Also even with your main power totally off, a hot voltage can be entering your electrical system from the electric company neutral wire via a neighbor's malfunctioning appliance. And you could be electrocuted while connecting or disconnecting a main ground wire.

And the other way around... A neighbors malfunctioning electric system could be placing a hot voltage on the city water pipe system. So if your ground wire is disconnected, there could be a difference in potential which could electrocute you.

The biggest danger is from one hand to the other hand and this goes through the heart.

"A domestic power supply voltage (110 or 230 V), 50 or 60 Hz alternating current (AC) through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60 mA..." From...
Electric shock - Wikipedia, the free encyclopedia

Anyway *assume* those ground wires are hot when you handle them. We don't want to see you "fibrillating"! Please be careful is all...
Great point! You are so very correct and I wonder if this is why the new code wants the power company basically completely disconnected from the house when a gen is used.....??
 
  #26  
Old 11-28-11, 02:37 AM
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  #27  
Old 11-28-11, 08:44 AM
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OSHA rules are for portable generators used at construction sites. OSHA covers the safety of workers.

NEC covers the connection of generators to homes.

The reason you would switch the neutral is because a generator has a GFCI. If the neutral is left connected to the home electrical system with a generator which has a GFCI, the GFCI will trip.
 
  #28  
Old 11-28-11, 09:29 AM
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Originally Posted by Ontheborder View Post
I wonder if this is why the new code wants the power company basically completely disconnected from the house when a gen is used.....??
There are two reasons: one is to allow GFCI protection to function correctly, and the other is that in a rare specific circumstance the connected neutral could be a shock hazard however that would require significant failure of the home's grounding system.
 
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Old 11-28-11, 09:35 AM
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Arent all the osha rules taken from the NEC?

The reason you would switch the neutral is because a generator has a GFCI. If the neutral is left connected to the home electrical system with a generator which has a GFCI, the GFCI will trip.
I thought with too many bonds the GFI will not trip when there is a fault? Too many paths for the fault to go???


Arent all Gens with GFCI outlets bonded? It would seem thats where the code is going with regards to neutral switching.

All Gens I believe will be produced bonded and with GFCI's now or in the future. Hence now the need to unbond at the panal with these new neutral switching types.

This will allow anyone no need to mess with the gen wiring from the factory. The gen will be able to be used as is in a stand alone situation. And simply hooked to the home with a neutral switching transfer switch.

Makes thinks simple. No modifications to the gens needed.

Mike NJ
 
  #30  
Old 11-29-11, 07:16 PM
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Originally Posted by lawrosa View Post
Arent all the osha rules taken from the NEC?



I thought with too many bonds the GFI will not trip when there is a fault? Too many paths for the fault to go???


Arent all Gens with GFCI outlets bonded? It would seem thats where the code is going with regards to neutral switching.

All Gens I believe will be produced bonded and with GFCI's now or in the future. Hence now the need to unbond at the panal with these new neutral switching types.

This will allow anyone no need to mess with the gen wiring from the factory. The gen will be able to be used as is in a stand alone situation. And simply hooked to the home with a neutral switching transfer switch.

Makes thinks simple. No modifications to the gens needed.

Mike NJ
This is where I was going, but I have yet to see a Simple transfer switch with a neutral switching in it. One with no meters, outlets, breakers etc, just a simple 3 switching unit. So I went and looked at a brand new install, and saw a 2 pole ( hots) simple switch, the neutral was fed inside and the Gen side was capped, so the only bonding is when the power company is switched on up making it a "separately Derived System" I also looked at 3 others from last year and just the hots are switched with the same box, and there was no issues with them...that were mentioned by the electrician.
 
  #31  
Old 11-29-11, 09:15 PM
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the neutral was fed inside and the Gen side was capped, so the only bonding is when the power company is switched on up making it a "separately Derived System"
No I dont think thats right. And I really dont know this end of the electrical part. I would have to draw it out. But then you have no neutral to your circuits.

If the neutral is capped on the gen side as you say then your circuits running off the gen are not bonded. Right?

Sure the gen may be bonded itself but it ended where you capped the line from the gen side. What about all the appliances and outlets in the home running off the gen? How will a fault get back to the source which is the generator?

The neutral transfer switches used with two seperatly derived systems, ( Each one bonded gen and panal) switch off the utility neutral to the circuits and switch it to the gen neutral to the circuits I am pretty sure. The two are isolated from one another.

Thats why its easier just to unbond the gen and just run the neutral to the panal.

And if it was so easy to just cap the gen side neutral why would'nt they just instruct to do that with two bonded sources?

The transfer switch would have to be rated for service entrance or a rated disconnect would have to be installed if you chose to keep the gen bonded. Thats why you dont see standard transfer switches with neutral switching

Make sense?





Look at 2nd diagram ( Cant remove top one for some reason)
Here is a normal diagram of the panal bonded and gen not bonded. See the neutral? It ties to the panal.

You stated you did or want to cap the gen side neutral. Its not tied to the circuits then.




Now here is a digram of two bonded sources which is the panal and the gen.

Its what you have. And are trying to figure a way to keep your gen bonded and the panal bonded. The panal is still bonded but the neutral is switched. The neutral needs to be switched from panal source to gen source and still feed the load.





Link to above diagrams and info.
3-Pole and 4-Pole Transfer Switch Switching Characteristics by EATON


Here is a few additional reads.

Switching the Neutral: What's the Controversy?

And this.

http://www.genpowerproducts.com/file...he Neutral.pdf




Hope this helps.


Mike NJ
 

Last edited by lawrosa; 11-29-11 at 10:53 PM.
  #32  
Old 11-30-11, 05:27 PM
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I have yet to see a Simple transfer switch with a neutral switching in it. One with no meters, outlets, breakers etc, just a simple 3 switching unit
That would be a 3 pole transfer switch you would be looking for, they aren't uncommon.

Connection for a Separately Derived System:
1. For generators that are configured as a Separately Derived
system. These units typically contain GFCI protection on the
generator.
a. Connect the two hot wires from the utility to the utility
breaker poles #1 and #2. Connect the utility neutral to the
utility breaker pole #3. See Figure 2 for clarification.
b. Connect the two hot wires from the generator to the
generator breaker poles #1 and #2. Connect the generator
neutral to the generator breaker pole #3. See Figure 2 for
clarification.
www.eaton.com/Electrical/USA/ProductsandServices/Residential/GeneratorsTransferSwitches/ProductLiterature/idcplg%3FIdcService%3DGET_FILE%26RevisionSelectionMethod%3DLatestReleased%26Rendition%3DPrimary%26dDocName%3DCT_253031+3+pole+manual+transfer+switch&hl=en&gl=us&pid=bl&srcid=ADGEEShn2M6vBxk4NTDW_XdSD8hBYVMD_UOmJeJ9Q5E1iW5WY1L-l81Blm2g5VUZVj-zfQIMkpFyhwTZHjTyQPntS1BIfj9Y60pcFxS3AHX5vsxzSicmfMy1ZvysA6dpbfbO3iO4fGBH&sig=AHIEtbRzmIXVvnxDsq8oJFglX9ZTLebx5g]Powered by Google Docs[/url]

Here's another, but automatic.

http://www.cat.com/cda/files/99858/7/LEHE4651-03.pdf
 
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