[shawneegaming]

Hello, I've attached a picture of a setup I am about to start wiring up but I had a few concerns.

1. I've read about issues(on this forum) with neutral path between two main panels at the link below but could not come to a conclusion in reference to my question below #2.

2. My setup pictured seems fine to run assuming no utility but when the utility comes back on(while I am on generator) and I have no disconnect for the utility neutral....is that going to be an issue? Also now there would be a connection between neutral and ground for everything in the house.

3. Does the generator need an earth ground? I feel like it does not since I am getting a heavy gauge ground from my panels direct to the generator. There is continuity between the grounds(and neutrals) on the generator receptacles and the earth ground lug on the generator frame.

4. Would I be able to run one panel off the generator while the other panel is still utility fed? It would be nice for yearly testing to run just the 2nd floor panel while the main panel is still utility fed. Obviously I would need to open the main for the 2nd floor panel but still I am concerned about the neutral from the meter now being connected to ground by my generator(and also all neutrals from both panels now being bonded to ground).

5. Should I just disconnect the ground wire from both generator leads and earth ground the generator? Keep in mind the generator frame is still bonding the neutral and ground.

Thanks in advance for your time.

 

[RAL238]

If you are back feeding the two panels without some kind of interlock or transfer switch, you are creating a dangerous situation which might kill someone. I don't know of an interlock which will allow you to interlock the generator with both panels simultaneously, so you are in trouble right there. How are you connecting the generator cord to the panels? You don't show any inlet boxes.

The right way to do this would be to install a transfer switch between the meter and the two panels so you can isolate the two panels from the utility mains together.

 

[shawneegaming]

If you are back feeding the two panels without some kind of interlock or transfer switch, you are creating a dangerous situation which might kill someone. I don't know of an interlock which will allow you to interlock the generator with both panels simultaneously, so you are in trouble right there. How are you connecting the generator cord to the panels? You don't show any inlet boxes.

The right way to do this would be to install a transfer switch between the meter and the two panels so you can isolate the two panels from the utility mains together.

Sir, in my picture I note an interlock breaker at the top right of each panel. Certainly I would not attempt without that. There is an inlet box on each cord as well that I have planned but I didn't show for simplicity of the drawing.

 

[shawneegaming]

Sir, in my picture I note an interlock breaker at the top right of each panel. Certainly I would not attempt without that. There is an inlet box on each cord as well that I have planned but I didn't show for simplicity of the drawing.

To clarify my procedure would be to open both utility main breakers, operate the interlock brackets and close the generator breakers. I just have a lot of questions about the neutrals and grounds but I might be over thinking it. Thanks in advance.

 

[shawneegaming]

Also another note to clarify on the application. This is normal residential two story house. Both panels are side by side in the garage fed by a single utility meter box outside.

 

[Kevin_Essiambre]

Hello, I've attached a picture of a setup I am about to start wiring up but I had a few concerns.



1. I've read about issues(on this forum) with neutral path between two main panels at the link below but could not come to a conclusion in reference to my question below #2.

I'm not sure about this, but I can help with other questions here.

2. My setup pictured seems fine to run assuming no utility but when the utility comes back on(while I am on generator) and I have no disconnect for the utility neutral....is that going to be an issue? Also now there would be a connection between neutral and ground for everything in the house.

The neutral not having a disconnect will be fine, as I will explain in a moment.

3. Does the generator need an earth ground? I feel like it does not since I am getting a heavy gauge ground from my panels direct to the generator. There is continuity between the grounds(and neutrals) on the generator receptacles and the earth ground lug on the generator frame.

The code where I am (Ontario Canada) states that no additional ground is required for a portable generator (which code says is under 12KW). I'm not sure what code says in your area.

4. Would I be able to run one panel off the generator while the other panel is still utility fed? It would be nice for yearly testing to run just the 2nd floor panel while the main panel is still utility fed. Obviously I would need to open the main for the 2nd floor panel but still I am concerned about the neutral from the meter now being connected to ground by my generator(and also all neutrals from both panels now being bonded to ground).

Yes, you will be able to run 1 panel independent from the other on generator power.

5. Should I just disconnect the ground wire from both generator leads and earth ground the generator? Keep in mind the generator frame is still bonding the neutral and ground.

No. However what you will need to do, is remove the neutral bond connection in your generator. The instruction manual should explain how to do this.

Because you are using interlock kits on the panels, you will need to remove the neutral bond connection in the generator. An interlock kit does not switch the neutral, and can cause issues with there being 2 neutral bond points.

I see no issues with using an interlock kit on 2 different panels hooked up to 1 generator. The only issue I see is the neutral bond connection that will have to be disconnected.

Of course, I may have overlooked something, but if I did, the others will mention it.
@CodeMatters what do you think?

Sent from my new phone. Autocorrect may have changed stuff.

 

[shawneegaming]

Thanks for the info Kevin!

Here is that other thread where someone has a similar situation and is asking about the neutral path between two main panels: https://www.diychatroom.com/f18/neutral-path-between-two-main-panels-116026/

 

[Kevin_Essiambre]

Thanks for the info Kevin!

Here is that other thread where someone has a similar situation and is asking about the neutral path between two main panels: https://www.diychatroom.com/f18/neutral-path-between-two-main-panels-116026/

Ah, I understand what they were talking about.

Because both panels are wired, adding a generator that is connected to both would cause 2 paths back to the source of the power. That's why someone in that thread said to use 2 separate inlets for the 2 separate panels, because only when the generator is connected would there be a parallel path.

That being said, I'll admit that I still don't know enough about this issue to comment on it. Someone else may know better.

Sent from my new phone. Autocorrect may have changed stuff.

 

[shawneegaming]

Based on the feedback from @Kevin_Essiambre and to clear up questions from @RAL238 I've created a new hand drawn(apologies) diagram with the N-G bond removed at the generator head. My primary question at this time is to determine if an additional neutral bond at the generator is an issue. IE with both plugs connected to the generator I am now tieing the neutral bars from both panels together via generator head, is that a concern?

 

[Kevin_Essiambre]

Paging @CodeMatters

Sent from my new phone. Autocorrect may have changed stuff.

 

[shawneegaming]

I've also attached a picture of the wiring diagram from the inside of my breaker panel. It would appear that neutral and ground are bonded in both of my panels. Which probably comes as no surprise to the people here.

 

[Kevin_Essiambre]

I've also attached a picture of the wiring diagram from the inside of my breaker panel. It would appear that neutral and ground are bonded in both of my panels. Which probably comes as no surprise to the people here.

I kind of figured this might be a possibility. You're in the USA, correct? Its completely different code down there from here in Canada, and I don't know enough to fully comment or reccomend things.

Sent from my new phone. Autocorrect may have changed stuff.

 

[CodeMatters]

Just 4 comments:
1) Can't see why it wouldn't work.
2) Wouldn't be approved in Canada. Violates barriered combination panel
principles, but the US/NEC doesn't have these rules.
3) Don't know NEC well enough to know if there's violations there.
4) This is the sort of unusual job I'd run by an inspector before starting.

Hmm...one more thought....it really isn't much different than two side by
side houses where the neutrals (and hots) are connected together at the
transformer. Nothing stopping both houses from having a generator
connected and running.....

Maybe @Fishbulb28 will have thoughts....if that's correct username.

 

[shawneegaming]

@Kevin_Essiambre
Yes sir! Oklahoma, USA
@CodeMatters
Thank for the info! That is a good point about the multiple connections at a utility transformer. I would imagine large chunks of a neighborhood might be sharing a neutral in some manner. Maybe I have been overthinking it this entire time.

@All
I've attached an updated diagram to show how my system is currently N-G bonded(which I have not modified) that might help in the discussion.

Also it might be worth noting that I could drop the neutral from the 30amp plug and just send two hots because the two panels are tied through the meter with large heavy gauge neutral wiring from the meter neutral common and the 50amp plug would send the neutral from the generator already. That might eliminate the concern of another neutral bond at the generator. If there even is a concern that is.

 

[Kevin_Essiambre]

@Kevin_Essiambre

Yes sir! Oklahoma, USA

I would have never guess Oklahoma.

That is a good point about the multiple connections at a utility transformer. I would imagine large chunks of a neighborhood might be sharing a neutral in some manner. Maybe I have been overthinking it this entire time.

Literally every building will share a neutral, due to the design of the system.

@All

I've attached an updated diagram to show how my system is currently N-G bonded(which I have not modified) that might help in the discussion.



Also it might be worth noting that I could drop the neutral from the 30amp plug and just send two hots because the two panels are tied through the meter with large heavy gauge neutral wiring from the meter neutral common and the 50amp plug would send the neutral from the generator already. That might eliminate the concern of another neutral bond at the generator. If there even is a concern that is.

I believe not using the neutral on one inlet would be a code violation... by that, I mean where I am it absolutely would be.

With 2 inlets, there is nothing stopping you, or anyone else from using 2 generators, one for each inlet. This, I would say is great in theory, but bad in practice.

I don't want to say too much, because we are on entirely different code books (I don't even know what year Oklahoma is on).

Paging @Fishbulb28


Sent from my new phone. Autocorrect may have changed stuff.

 

[Fishbulb28]

Dutifully summoned, the Fishbulb springs forth with all the speed of... a one legged turtle. With a broken leg. And narcolepsy.

Is the OP still here?

I've attached an updated diagram to show how my system is currently N-G bonded(which I have not modified) that might help in the discussion.

It won't be code compliant because you are creating a parallel conductor path. That doesn't mean it will be any more unsafe than if done 100% to code. Here's why.

You could make it compliant by installing a switched neutral main breaker (not available for your panel anyway) in one or both of the panels. This would disconnect the neutral conductor between the two panels when the main breaker is off and avoid the parallel situation via the service neutral conductor.

But there's likely already another parallel current path installed. The most common method used to ground the service with two service panels is to connect the grounding electrode conductor to each panel. Have a look at the attached diagram. This creates a parallel connection between a portion of the grounding electrode conductor and the service neutral. So you would install the switched neutral breaker, now have the installation 100% compliant, and still you would have the very same situation.

Make your installation as you've planned and don't lose any sleep over it. Just be aware you might not be able to justify it if pressed.

Also it might be worth noting that I could drop the neutral from the 30amp plug and just send two hots because the two panels are tied through the meter with large heavy gauge neutral wiring from the meter neutral common and the 50amp plug would send the neutral from the generator already.

No, don't do that. The neutral conductor is the most important in the feeder. If you or someone else should connect and use only the 30A cable you would create a situation where the 120V circuits actually receive anywhere from 0V-240V. Do a search for "lost service neutral" if you want the reasons for this.

 

[shawneegaming]

Dutifully summoned, the Fishbulb springs forth with all the speed of... a one legged turtle. With a broken leg. And narcolepsy.

Is the OP still here?

I've attached an updated diagram to show how my system is currently N-G bonded(which I have not modified) that might help in the discussion.

It won't be code compliant because you are creating a parallel conductor path. That doesn't mean it will be any more unsafe than if done 100% to code. Here's why.

You could make it compliant by installing a switched neutral main breaker (not available for your panel anyway) in one or both of the panels. This would disconnect the neutral conductor between the two panels when the main breaker is off and avoid the parallel situation via the service neutral conductor.

But there's likely already another parallel current path installed. The most common method used to ground the service with two service panels is to connect the grounding electrode conductor to each panel. Have a look at the attached diagram. This creates a parallel connection between a portion of the grounding electrode conductor and the service neutral. So you would install the switched neutral breaker, now have the installation 100% compliant, and still you would have the very same situation.

Make your installation as you've planned and don't lose any sleep over it. Just be aware you might not be able to justify it if pressed.

Also it might be worth noting that I could drop the neutral from the 30amp plug and just send two hots because the two panels are tied through the meter with large heavy gauge neutral wiring from the meter neutral common and the 50amp plug would send the neutral from the generator already.

No, don't do that. The neutral conductor is the most important in the feeder. If you or someone else should connect and use only the 30A cable you would create a situation where the 120V circuits actually receive anywhere from 0V-240V. Do a search for "lost service neutral" if you want the reasons for this.

Thank you fishbulb. That all make sense to me. One final question...should I remove the N-G bond in the generator? I know this is a hot topic and I understand doing so will make the generator unsafe for field use. I also understand that it would probably work both ways in reality. Also that my system is neutral ground bonded at the panels down stream of the generator as well. Do you have any words of wisdom on that topic? I was leaning towards just leaving it bonded(factory condition) to be honest. But I’ve already scouted out the area to remove the bond and it’s quite easy.

Thanks again!

Alan

 

[Let it Snow]

If you are back feeding the two panels without some kind of interlock or transfer switch, you are creating a dangerous situation which might kill someone. I don't know of an interlock which will allow you to interlock the generator with both panels simultaneously, so you are in trouble right there. How are you connecting the generator cord to the panels? You don't show any inlet boxes.

The right way to do this would be to install a transfer switch between the meter and the two panels so you can isolate the two panels from the utility mains together.

Exactly, Stop! Your design is dangerous and could kill a power company lineman. It's possible to backed the utility transformer.

Let's say the voltage on the pole or underground is 21,000 volts. The transformer reduces this to 120/240. When you leave a main breaker at your panel, ON by mistake, it will take the 120/240 volt backfeed and produce 21,000 volts on the utility side. A Lineman thinks the power is OFF in your area, but you made it LIVE. DEAD LINEMAN.

 

[shawneegaming]

If you are back feeding the two panels without some kind of interlock or transfer switch, you are creating a dangerous situation which might kill someone. I don't know of an interlock which will allow you to interlock the generator with both panels simultaneously, so you are in trouble right there. How are you connecting the generator cord to the panels? You don't show any inlet boxes.

The right way to do this would be to install a transfer switch between the meter and the two panels so you can isolate the two panels from the utility mains together.

Exactly, Stop! Your design is dangerous and could kill a power company lineman. It's possible to backed the utility transformer.

Let's say the voltage on the pole or underground is 21,000 volts. The transformer reduces this to 120/240. When you leave a main breaker at your panel, ON by mistake, it will take the 120/240 volt backfeed and produce 21,000 volts on the utility side. A Lineman thinks the power is OFF in your area, but you made it LIVE. DEAD LINEMAN.

Let it snow,
Can you please read the descriptions and diagrams before commenting in this manner. I have interlock breaker kits on BOTH panels. It is NOT possible to accidentally leave a main breaker on.

 

[AllanJ]

Psst! Using your generator to feed only one panel via backfeed breaker with a defective or no interlock is equally dangerous to persons outside as feeding two panels as you have described!

With your two panels wired as you describe and correctly interlocked, if only one panel is energized with the generator, that panel can't send generator power to the utility lines. And the other panel still on utility lines can't get any power from the generator.

Even with unswitched neutrals and unbroken neutral-ground bond in the generator.