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MPP LVX6048 are the Neutral and Ground bonded inside when using only battery input?

EchoPapa

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MPP LVX6048: Are the Neutral and Ground bonded inside when using only battery input?
If this is true when back feeding a main panel there will be a ground loop when between the main panel (N-G bonded) and the LVX6048 ( N-G bonded). Can it be confirmed that the LVX6048 operation is identical to the LV6048 in respect to N-G bonding operation?
If so, does the LVX6048 also have a screw that can be removed to remove the internal N-G bond when in battery input only mode?
 
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I have not seen any indication that my LVX6048s do any internal bonding. In fact, I gave myself a nice little jolt when I forgot to bond downstream at one point and ended up with 130v between neutral and ground; doesn't much help to kill the hot side breaker on a circuit in that situation.
 
This is what MPP Solar sent me:

"All our inverters will bond output N-G under battery mode, where as under line mode (grid bypass) they will remain OPEN. this is the way it is normally installed."
 
This is what MPP Solar sent me:

"All our inverters will bond output N-G under battery mode, where as under line mode (grid bypass) they will remain OPEN. this is the way it is normally installed."
I can confirm this is the case in Battery & Solar input mode. The issue is if you backfeed into a main panel via a backup generator plug 30 amp breaker you will create a N-G loop and your GFI breakers will trip. Typically gas generators do not have a N-G bond.
A N-G bond somewhere in the system will be required to be opened to work without current being applied to the ground circuit.
Suggestions?
 
I can confirm this is the case in Battery & Solar input mode. The issue is if you backfeed into a main panel via a backup generator plug 30 amp breaker you will create a N-G loop and your GFI breakers will trip. Typically gas generators do not have a N-G bond.
A N-G bond somewhere in the system will be required to be opened to work without current being applied to the ground circuit.
Suggestions?
For a different inverter, I just bonded at the generator and then used a 3 pole breaker in between with all three legs switched; kill that before killing the generator.

If @niktak11 is correct, I may have to do that with the lvx as well. After figuring out why it *isn't* bonding. :|
 
I can confirm this is the case in Battery & Solar input mode. The issue is if you backfeed into a main panel via a backup generator plug 30 amp breaker you will create a N-G loop and your GFI breakers will trip. Typically gas generators do not have a N-G bond.
A N-G bond somewhere in the system will be required to be opened to work without current being applied to the ground circuit.
Suggestions?
That's a good point. I've back fed my main panel with the LVX panel before but I don't have any GFCI breakers.
 
If I'm understanding this correctly then a power outage will cause a ground loop???? If I'm bonded at the main panel per code but lose the AC mains, then the inverter automatically bonds N-G internally so now I've got 2 N-G bonds. Or does the inverter sense continuity between neutral and ground on the AC input and close the circuit internally only if it doesn't "see" continuity...
 
If I'm understanding this correctly then a power outage will cause a ground loop???? If I'm bonded at the main panel per code but lose the AC mains, then the inverter automatically bonds N-G internally so now I've got 2 N-G bonds. Or does the inverter sense continuity between neutral and ground on the AC input and close the circuit internally only if it doesn't "see" continuity...
Yes.
The LVX6048 has a N-G bond controlled by an internal relay. The relay is normally closed (N-G bong created) and open only when power is applied to the Grid/Generator 240VAC input to the LVX6048. Thus, when operating only off the DC input from Solar or Batteries there is an internal N-G bond. If it is feeding a typical main panel which also has a N-G bond a Ground loop will be created with current present on the ground wire because there are dual paths for current to travel. Any GFIs in the main panel will not function properly.
 
If I'm understanding this correctly then a power outage will cause a ground loop???? If I'm bonded at the main panel per code but lose the AC mains, then the inverter automatically bonds N-G internally so now I've got 2 N-G bonds. Or does the inverter sense continuity between neutral and ground on the AC input and close the circuit internally only if it doesn't "see" continuity...
Parallel paths from having 2 N-G bonds in a system will cause half of the current to flow on G between the 2 N-G bonds.

The way to fix this is having a subpanel after the inverter which is not bonded. The inverter will switch N with the internal transfer switch.

You have a few choices, one is a transfer switch that switches N or installing a main panel ahead of the inverter with N-G bond and a subpanel after the inverter with the desired loads. Plenty of wiring diagrams in the various threads here. And discussion.

If you want to backfeed grid, well, that's a whole different ball game.
 
Yes.
The LVX6048 has a N-G bond controlled by an internal relay. The relay is normally closed (N-G bong created) and open only when power is applied to the Grid/Generator 240VAC input to the LVX6048. Thus, when operating only off the DC input from Solar or Batteries there is an internal N-G bond. If it is feeding a typical main panel which also has a N-G bond a Ground loop will be created with current present on the ground wire because there are dual paths for current to travel. Any GFIs in the main panel will not function properly.
So if you are off grid with a generator as backup, would you then just treat the service panel that the LV feeds as a sub panel or bond the G and N and just not have gfci bc of the genny? What about afci vs the genny? AFCI sounded nice for potential fire issues, but now I'm lost if the cabin panel should be bonded or not. I had planned to add AFCI everywhere (except garage, bath, and outside) GFCI only in the bath, and dual in the kitchen per current code.

If you remove the screw you can then bond at the panel, but it sounds like it could cause issues in the inverter.during a fualt. But then the genny screws up the gfci.

If you bond the inverter by keeping the screw and essentially make the main panel a sub panel then will the breakers work correctly and have an overcurrent flip during fualt and or will your cabin be as safe?
 
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