Ground/neutral bond? (EG4 3kw)

Burnrate

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I have read a lot of the other threads about this and basically understand the problem is you don't want to have a ground neutral bond in multiple places. This seems like it means that using the EG4 3kw in split phase for 240 volts would not be possible?

They show that you can use them in split phase for 240 volts though (on page 55 of the manual) 1655056435561.png


Is the problem really with having the G/N bond in the inverter and also on the panel? What if you have a transfer switch and the bond occurs on the meter and not the panel and you are not using the AC input? That would mean that you only have the G/N bond in the inverters but again it is in each inverter? Is the discussion about all these inverters that they have a fundamental flaw? Do all other inverters just expect people to do their own G/N bond in the panel?

If the G/N bond is in the panel can you simply not connect the AC output Ground wire?

There is also this section on page 17. It says when in PV/battery or standby AC output Neutral is connection to AC input ground. It then says when it is in AC mode the AC output Neutral is connected to the AC input Neutral (not ground). It doesn't talk about any of these modes anywhere in the manual. By mode do they mean the PV/battery functionality? Are they trying to imply the grounding of the unit changes on the fly as it switches from charging to providing power? Are you supposed to wire it differently depending on if you have an AC input? This "Important to Note:" is the worst part of this whole manual.
1655057037755.png

I feel like EG4 isn't a completely incompetent or evil company that would make such a terribly flawed product. Am I wrong? Do I not understand the purpose of this product?
 

FilterGuy

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I feel like EG4 isn't a completely incompetent or evil company that would make such a terribly flawed product. Am I wrong? Do I not understand the purpose of this product?
Completely evil?.... No. Flawed documentation? Yes Flawed product? Maybe.

As you have seen on other threads there is great debate about the bonding and what is (or isn't) needed to set things up properly. However, both camps of the debate have put out what they feel are workable solutions. Meanwhile, EG4 has said they are doing a comprehensive review of the questions and will get back to us with information.

If the G/N bond is in the panel can you simply not connect the AC output Ground wire?
There are times when you can technically forgo the AC Output Ground, but not because of the internal bonding. (More on this later in the post)

1655078496231.png
What this is telling you is that the inverter does dynamic Neutral-Ground Bonding.
* It will not create an N-G bond when in pass-through mode (The output AC is powered by the input AC).
* At all other times, it will create an N-G bond.


There are 3 places where there might be an N-G bond (4 if there is two inverters):

1) In the main breaker panel.
2) Inside the inverter(s)
3) In the critical loads panel.

At any given time there should be exactly one N-G bond. Zero N-G bonds is a problem and more than one N-G bond is a problem.

I put together this resource to help explain how to set up the EG4 65000.


I have sent this to EG4 and they said they would review it but I have not heard back. (I am getting impatient, but I suspect they are trying to be extremely thorough and careful about this in order to avoid making things worse)

Full disclosure:
There are people on the forum that believe it is OK for both inverters to generate N-G bonds and disabling the NG bond inside the inverter is unnecessary. (I do not agree with them...... but since there is a disagreement I feel obligated to acknowledge the different points of view.)

About grounding. If there are loops in wiring, they can become antennas that will broadcast Radio Frequency Noise and inverters are infamous for creating noise that could be broadcast. Consequently, I highly recommend avoiding loops when inverters are used. The most common place that loops get generated is in the wiring of Equipment Grounding Conductors (ground wires). Consequently, even though everything should be grounded, you want to avoid ground loops. However, the NEC can make this difficult because it requires the Equipment Grounding Conductors be run with the non-grounded conductor (The hot conductor). You will see that in the above document I show many of the EGCs run with the non-grounded conductors but only connected on one end if there is already a ground connection at the destination.
 

Burnrate

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I put together this resource to help explain how to set up the EG4 65000.

Thank you so much for this detailed response (and wonderful document).

One more question, in the document you recommend having one inverter having a N/G bond when they are setup to receive AC power from a panel that already has a N/G bond (configuration 6 as an example). Why would you recommend this instead of removing the N/G bond from both inverters and relying on the bond in the panel.
 

FilterGuy

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One more question, in the document you recommend having one inverter having a N/G bond when they are setup to receive AC power from a panel that already has a N/G bond (configuration 6 as an example). Why would you recommend this instead of removing the N/G bond from both inverters and relying on the bond in the panel.
If you removed both N-G bonds from the inverters and added an N-G bond in the critical load panel, then there would be two N-G bonds when the inverters are in pass-through mode.
 

Burnrate

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If you removed both N-G bonds from the inverters and added an N-G bond in the critical load panel, then there would be two N-G bonds when the inverters are in pass-through mode.
Oh that makes absolute sense, if you removed the N/G bond from both inverters you would have no bond at all when running off of batteries and end up killing someone.
 

FilterGuy

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I am assuming you are doing this in a stationary system (not an RV). For a stationary system, there is a configuration with both bonding screws removed that some people use but it is not clear if EG4 supports it: I call it a 'common neutral' system and it is where the input and output neutral end up being tied together.

In the document I show a common neutral system like this:
1655142695027.png


In this case, the loads will always 'see' the N-G bond in the main breaker panel so so all other N-G bonds should be removed. This holds true for two inverter systems as well, so the bonding screws for both inverters should be removed.

I have a question out to my contact at EG4 about whether they support common neutral, but so far they have not responded (It has been about 3 weeks.... so maybe I'll ping them again)

Note: In my opinion, Common Neutral is the best way to go for stationary systems. Dynamic bonding adds a lot of complexity and is only needed in mobile systems where the N-G bond from shore power comes and goes.
 

bones1

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Interesting. I am at the point in the installation where I need you guys help. I have the same breaker panel that Will uses in his video install and I have removed both bonding screws in the inverters as well. picture below. I notice that he has the green bonding screw installed and the grounds and neutrals tied together and his is not going to another panel or xfer switch, just outlets I believe. My setup is going out to a Generac panel with a built-in xfer switch, previously used for a generator.I have 2 hots and a neutral and ground going over to the xfer switch as it was wired for the generator at one time. Should I keep the small panel wired as is with the bonding screw and grounds and neutrals connected together or separate them and/ or remove the green bonding screw? From this panel, it goes to the large 200A home panel which has a built-in xfer switch. A link to the xfer switch panel, I don't think it's switching neutrals
1659476679183.png
 
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