EG4 Official Neutral Ground Bond Thread.

[timselectric]

Can you send a picture of correct wiring for a sub panel combining two inverters and then feeding a main panel?

Sub panels don't feed main panels.
It's the other way around.

 

[Adam De Lay]

The "inverter combiner panel" basically becomes your "main panel" for all intents and purposes because it's the first panel after the power supply (the inverters). So anything else after that panel becomes a "sub panel" (even if it's your main distribution panel of the house).

It's a terminology thing, but still important to be able to differentiate.

 

[dcg9381]

Can you send a picture of correct wiring for a sub panel combining two inverters and then feeding a main panel?

In the non-mobile case, what he's saying is that the "main" (first panel - where you bring the inverter power to) has a neutral/ground bond and subsequent "sub"-panels are not bonded netural-ground.

Basically it's the same as wiring a home:

• The first panel after the power source (typically the meter) is bonded neutral ground
• Subsequent panels (sub-panels) are not neutral ground bonded

 

[Hedges]

Sub panels don't feed main panels.
It's the other way around.

You want to see me?!
Just watch! ?

 

[dcg9381]

You want to see me?!
Just watch! ?

Not to confuse anyone, but this is an interlock, probably for a generator. (Trying to keep it simple for those new to neutral/ground bonding)

 

[Mattb4]

Interesting but actual grounding requirements are not mentioned. For anyone that is using a setup without AC in there needs to be a place you establish a proper system ground (ground rods) which than has to feed to where NG is bonded.

 

[timselectric]

You want to see me?!
Just watch! ?

When activated. That is now the main panel. lol

 

[mountkay]

Can you send a picture of correct wiring for a sub panel combining two inverters and then feeding a main panel?

Here is how my off grid system is wired. I’m sorry for using the wrong terminology and spreading confusion.



Using the correct terminology now:
My “Main Panel” (or inverter combiner panel) only has 1 breaker (2-pole) and it is right after the inverters.

My “Sub Panel” is what came with the home and has the breakers for the entire house.

Currently I have my G/N bond in my Main Panel. Just need to remove the G/N bond from one of my inverters (the 2nd one came without it).

 

[Hedges]

Not to confuse anyone, but this is an interlock, probably for a generator. (Trying to keep it simple for those new to neutral/ground bonding)

Exactly.

My main panel is configured like this.
It has a breaker feeding grid input of Sunny Island inverter/charger (actually used to before I connected those differently.)
Sunny Island feeds a sub-panel or PV aggregator panel, with feeds a sub-panel in the house.
It also goes back to the interlocked "Generator" breaker like in photo.

During a power outage I could manually turn off breaker feeding Sunny Island and turn on Generator breaker.
That feeds main panel from battery/PV powered sub panel, so any and all loads could be powered.
Only issue with that is it does not automatically switch back to grid when power restored, and no circuits to indicate if grid is up.

(neutrals and ground are unswitched and continuously connected everywhere. Neutral/ground bond occurs at meter box, which actually has another 200A breaker; that allowed me to move connection for Sunny Island.)

 

[Zwy]

Hopefully you are just saying this backwards?

Won't matter if neutral is now pass thru. All "ground faults" are actually neutral faults and that is what trips the breaker. With G and N passing thru the inverter with the latest firmware, the N-G bond can be in the main panel.

 

[timselectric]

Won't matter if neutral is now pass thru. All "ground faults" are actually neutral faults and that is what trips the breaker. With G and N passing thru the inverter with the latest firmware, the N-G bond can be in the main panel.

Was referring to N/G bond in sub panel.
The wording was backwards.
The N/G bond can only be in the main panel.

 

[ThePatriotDude]

Similar question to what’s happening here but different.

I have two EG4 6k inverters landed in a main panel where the neutral and ground are bonded and I have a separate panel only for the generator that directly feeds the two inverters and in the generator panel the neutral and ground are separated. This generator panel does not connect to the main panel at all. I have separate ground rods for both panels. The generator inlet separates the neutral and ground and the plug is a 50amp inlet.

My question is, does the generator panel need to have the neutrals and ground’s separated or combined?

Note: My system is 100% off grid.
Note #2: The generator is a 9k pure sine wave inverter generator.

 

[timselectric]

Trying to decide where to start.

The generator inlet separates the neutral and ground

How does it do this?

 

[dcg9381]

Trying to decide where to start.
How does it do this?

The inlet has separate wires for neutral and ground (at least the 4 prong inlets I use).
The question is about how the generator is bonded.. And I think that's different between generators.

 

[Adam De Lay]

I have a separate panel only for the generator that directly feeds the two inverters and in the generator panel the neutral and ground are separated.

Trying to decide where to start.
How does it do this?

I wonder if he means his generator only panel.

 

[dcg9381]

I wonder if he means his generator only panel.

He needs to google "generator bonding". The answer here depends on his generator.
In a floating neutral generator, the neutral is not bonded to the generator's frame. Therefore, the ground must be provided by the generator panel.

 

[timselectric]

If the generator feeds the "generator panel". And the "generator panel" feeds the EG4"s. And the EG4's feed the "main panel". Then the generator is connected to the "main panel". This is one system and should only have one grounding system. And only one N/G bond.
Splitting the grounding can create a Hazzard.

 

[stumped]

Exactly.

My main panel is configured like this.
It has a breaker feeding grid input of Sunny Island inverter/charger (actually used to before I connected those differently.)
Sunny Island feeds a sub-panel or PV aggregator panel, with feeds a sub-panel in the house.
It also goes back to the interlocked "Generator" breaker like in photo.

During a power outage I could manually turn off breaker feeding Sunny Island and turn on Generator breaker.
That feeds main panel from battery/PV powered sub panel, so any and all loads could be powered.
Only issue with that is it does not automatically switch back to grid when power restored, and no circuits to indicate if grid is up.

(neutrals and ground are unswitched and continuously connected everywhere. Neutral/ground bond occurs at meter box, which actually has another 200A breaker; that allowed me to move connection for Sunny Island.)

Do your panels, inverters, and conductors look something like this? If, so what conductors (circled in orange) are you breaking when in a grid down topology?

Edit: This is a drawing of someone named "Stumped".
Don't attempt to duplicate in reality unless you know what you are doing to be correct.

 

[Hedges]

Your drawing has switch (circled in orange between inverters and main panel, opening Line and Neutral but not ground.
I have visible blade knife switch in that location, opening only L1 & L2, not Neutral or ground. (manual disconnect)

After knife switch I have two 2-pole Midnight/CBI 60A magnetic-hydraulic breakers, because I have four inverters.

My inverters internally open only Line. Both Neutral and Ground pass through. (automatic disconnect when grid down.)

Yes, Sub-panel feeds back to main panel as shown, but connects to main panel adjacent to main breaker (so the breakers can interlock.)
This path has a load-shed relay, so the sub-panel (with AC coupled Sunny Boy) remains powered even if loads are shed due to low battery.

Besides feeding back to main panel, it also feeds a sub-panel in another building (the house.)

*Edit* I don't feed neutral back as shown. I route L1 and L2 back through same conduit line, neutral, and ground came in.

So no loops, and no switch breaking loop. I have considered creating some loops on purpose, because if I do switch "line" between two different paths, I want a neutral adjacent (not wrapped around a piece of steel between them.) But I don't have that anywhere now.

My inverters are on a "T" branch of conduit, so wires don't run through them from main panel to sub-panel.
Neutral and ground go through the conduit branch, then have a splice and branch out to a stacked split-phase pair of inverters. They do not route back in another wire. L1/L2 input routes to the inverter, L1/L2 output routes back from the inverter. all inside same conduit.
Because I have four inverters, two split-phases pairs, there is a second copy of that.

Neutral doesn't form any loops at all. Ground does, because it wires from sub-panel with two wires to two pairs of inverters, and those inverters are mounted on the same metal rail. So multiple copper ground wires go to aluminum/steel structures in multiple places.

 

[stumped]

Thanks Hedges. I will have to chew on what you wrote to set it straight in my mind.

I don't want to have to go through all the trouble to unbond all the circuits in my main panel when the power goes out. And I don't want to move them permanantly to a sub panel or install a smaller main panel for service entry in front of what is now the main.

I believe my inverters (victron) pass neutral and ground between AC In and AC Out similarly. And if so, I could leave those conductors unbroken between the main panel and the inverters AC In. Thereby omiting it (neutral) from the circuuits run from the sub back up to the main. I know I can shut off the internal ground relay also when AC In is lost so that the ground/neutral bond at the main panel is the only place that they converge.

 

[Hedges]

Yeah, I think that should work, same as I did. Line and neutral (and ground) run to the inverter, only line runs back.
All you should have to do is thrown an interlocked generator breaker.

Or, use one of those Reliance transfer switch panels, with toggle switch and breaker per circuit. It has BX cable with wires you connect to main panel. Toggle switch selects either main panel breaker or Reliance (generator) breaker. For non-GFCI circuits (although I have a way to make them work), and be careful of any 3-wire plus ground wiring feeding separate 120V branches.

 

[trig2]

Now that it always uses common neutral can you just splice input/output neutral at the inverter now with one of these or do you still need separate neutral conductors back to the panel?

 

[Mithril]

Any word on if the EG4 3Kw units are impacted? Seems they also stopped shipping with the bonding screws at some point.
if the bonding screw is removed, is there harm in hard-wiring that neutral-neutral bond right at the inverter?

 

[timselectric]

Now that it always uses common neutral can you just splice input/output neutral at the inverter now with one of these or do you still need separate neutral conductors back to the panel?

Single neutral is fine. As long as the input and output hots travel together.

 

[Zwy]

Now that it always uses common neutral can you just splice input/output neutral at the inverter now with one of these or do you still need separate neutral conductors back to the panel?

I used a Polaris connector like that for neutral input of the inverters. For the inverter output, there is a small 70 amp breaker panel and both neutrals are attached to the busbar in that small panel. One inverter output neutral wire from the small panel to the transfer switch about 15 feet away.