EG4 6000XP Neutral-Ground Bonding

[HighTechLab]

Let's start with a snip from the EG4 6000XP manual.

What I'm getting at here, is a lot of people, including @Will Prowse in his latest video (8:03) are mistaken on how the 6000XP handles neutral and ground bonds. The inverter does NOT dynamically bond. This means that if you plan to put an cord and plug on the AC-input, then you will have problems (for example, if you plan to use this inverter in an RV). In my opinion, it's really only intended for hardwired applications, similar to the big-brother, the 18k-PV.

Neutral-ground bonds are critical in all modes of operation because it creates a fault current path so that you actually trip a breaker in the event of a ground fault. Without a neutral-ground bond, then all that happens during a ground fault is the cases of everything become live in relation to neutral and the fault is not cleared.

Double bonds are not acceptable by code or safe because it creates a parallel path for neutral currents. The current carried on the grounding conductor is know as objectionable current. NEC specifically addresses objectionable current.

The two options for successful and safe implementation are:

• Bond is either created upstream of the inverter, (in the main panel). Neutral and ground connections remain separate to the inverter (and any parallel connected inverters) and the relay in the inverter is left disabled). No cord-and-plug can be used between the main panel and the inverter. A hardwire connection is required so that the neutral and ground bond is maintained at all times, not just while plugged in.
• Bond is created in only one of the inverters, but there cannot be bonds upstream or downstream. This means if you decide to put a cord-and-plug, for example, an NEMA 14-50P (for an RV) or a 6-30P (for a generator), then you cannot plug the cord into a bonded system (for example, an RV park or generator with a bond). This would create a double-bond which is not permitted by code and cause objectionable current.

I would recommend if you plan to use these inverters in a mobile application, then you enable the bonding relay within the inverter and skip using the built-in charger/transfer switch function. When it comes time to recharge your batteries, just pick up one of the EG4 chargeverters (or 12) and use that as your input power source. Since the chargeverter is completely isolated from the inverter, the chargeverter prevents any chance of double-bonding.

@Markus_EG4 Let me know if I've missed anything here.

 

[FilterGuy]

I would recommend if you plan to use these inverters in a mobile application, then you enable the bonding relay within the inverter and skip using the built-in charger/transfer switch function. When it comes time to recharge your batteries, just pick up one of the EG4 chargeverters (or 12) and use that as your input power source. Since the chargeverter is completely isolated from the inverter, the chargeverter prevents any chance of double-bonding.

That is a good plan, but some folks want to be able to use the full 50A pass through.

There is a solution where a Relay is used external to the inverter to create the bond. If there is power on shore power the relay opens a normally closed relay that is creating the NG bond. If there is no shore power, the normally closed relay is closed and creating the NG bond.

 

[HighTechLab]

That is a good plan, but some folks want to be able to use the full 50A pass through.

There is a solution where a Relay is used external to the inverter to create the bond. If there is power on shore power the relay opens a normally closed relay that is creating the NG bond. If there is no shore power, the normally closed relay is closed and creating the NG bond.

We could argue code compliance for a relay in the middle of the main bonding jumper for hours but I'm going to pretend, for the sake of figuring out a solution that it doesn't matter. The inverter has a relay inside anyway but that's up to the AHJ to interperet.

What happens when a unbonded device (such as a portable generator) is plugged in? Then, the system wouldn't have any bonds. I started drawing a diagram where the coil of the relay was connected across hot and ground, so that the relay only broke the bond when there was a path for the circuit to be completed if a bond was present, only to realize it would absolutely oscillate if a ungrounded input were connected.

The main case-in-point I'm trying to figure out here is an RV application where the end-user could plug in a lot of different system topologies, some bonded and some not.

 

[hwy17]

It would be easier if we could all strictly separate mobile and stationary inverters. Like the Midnite Rosie comes in mobile with auto bond or stationary with no bond ever.

But people will always want to cross apply them.

The one use case that bugs me but won't go away and EG4 may feel like they are obligated to cater to is stationary no grid power with bond.

I don't want any bonding provisions in any stationary inverter I buy. I want to know 100% it does not and cannot.

 

[Adam De Lay]

Ah how I've missed these G/N Bond discussions... ?

Since the G/N bond in in the inverter is controlled by a relay, couldn't LuxPower add a 3rd option for the G/N controls which would make it more of a "dynamic" relay (similar to what the 6500s did by default). When AC In/bypass is used, the G/N bond is disabled and when in battery mode it's enabled? It seems like this inverter should be smart enough to be able to do this assuming it's programmed properly.

So you would have "Always On", "Always Off" or "Dynamic".

 

[Cmiller]

We could argue code compliance for a relay in the middle of the main bonding jumper for hours but I'm going to pretend, for the sake of figuring out a solution that it doesn't matter. The inverter has a relay inside anyway but that's up to the AHJ to interperet.

What happens when a unbonded device (such as a portable generator) is plugged in? Then, the system wouldn't have any bonds. I started drawing a diagram where the coil of the relay was connected across hot and ground, so that the relay only broke the bond when there was a path for the circuit to be completed if a bond was present, only to realize it would absolutely oscillate if a ungrounded input were connected.

The main case-in-point I'm trying to figure out here is an RV application where the end-user could plug in a lot of different system topologies, some bonded and some not.

Where does an RV fit into your code scenario? If I'm not mistaken, RV's wouldn't be under any local jurisdiction.

Technically you could unhook the ground wire from the plug at the inverter end, and have the bond on the RV after the inverter, and you wouldn't have any parallel path. The RV grounding would still have a connection (via the neutral wire) to earth-ground/ ground-rods in the dirt/ however you want to put it. (Because there are always controversies on how everything should be worded when you discuss grounding and bonding. )

I actually haven't ever really given much consideration on code compliance of setting it up the way I mentioned, in a scenario where you would have an AHJ. That could happen in a residential install, with a portable generator plug option for backup charging. (What if the gen has a bond..... what if a different one doesn't......)

There are a lot of RV specific inverters that have a bonding relay built-in that automatically disconnects the bond when plugged in...

I personally despise the thought of bonding relays. I would much prefer a fixed bonding jumper or machine screw, where I don't ever have to worry about it malfunctioning!

 

[Quattrohead]

I have pondered this many times as to which is worst, no neutral ground bond at all or neutral ground bond in two different places, which is worst and is either or both acceptable?
Even the latest video I don't feel comfortable with and I really want to test that AC input to see whether there is actually AC on those pins when it is unplugged and inverting, I would think not but you can't have plugs just hanging around not knowing whether they are live or not.
And yes in home on grid, in home off grid and RV are all different installation scenarios with different requirements and results.

 

[ksmithaz1]

I have pondered this many times as to which is worst, no neutral ground bond at all or neutral ground bond in two different places, which is worst and is either or both acceptable?
Even the latest video I don't feel comfortable with and I really want to test that AC input to see whether there is actually AC on those pins when it is unplugged and inverting, I would think not but you can't have plugs just hanging around not knowing whether they are live or not.
And yes in home on grid, in home off grid and RV are all different installation scenarios with different requirements and results.

If I grok the theory, you don't want multiple paths of different lengths,allowing a fault flow to go backwards. Thus bonding in two places 3 feet apart would seemingly not be a huge issue, but it's all about how the current will travel in the event of a fault. If it hits an early ground a breaker may not trip as desired.

 

[FilterGuy]

The main case-in-point I'm trying to figure out here is an RV application where the end-user could plug in a lot of different system topologies, some bonded and some not.

The reality is, even systems that do dynamic bonding well has to make assumptions about whether there is a bond on the AC in. I do not know of anything on the market that can handle AC-in without bonding sometimes and AC-in with bonding other times. It could be done with modern electronics that detect if a bond exists or not, but I am not aware of any current inverter product with that capability.

It would be easier if we could all strictly separate mobile and stationary inverters.

So true!!! The 6000XP has a design center of stationary installs. Trying to apply it to mobile is a little bit of a square peg and round hole situation.

 

[hwy17]

I have pondered this many times as to which is worst, no neutral ground bond at all or neutral ground bond in two different places, which is worst and is either or both acceptable?

Imo no bond at all is way worse than double bond. My property had a double bond in place for 20 years and in practice the objectionable current just isn't that big a deal.

 

[ksmithaz1]

Imo no bond at all is way worse than double bond. My property had a double bond in place for 20 years and in practice the objectionable current just isn't that big a deal.

Every time I watch the explanations, I'm like, "Yea that seems kind of esoteric, one in a million problem, with a double bond". Then again there are are more than a million installations of power so ... If everything else is always perfect it's irrelevant.

 

[Will Prowse]

Added this to my website blueprint. What do you guys think:

 

[Will Prowse]

And if you enable setting 26, I would imagine that it creates a bond in only one inverter regardless if you have 2 or 16 in parallel. So for offgrid use, it will create it where necessary. But if you are connected to grid, it needs to be manually changed.

@Markus_EG4 Do you think they can add an update where the bond relay opens when connected to mains?

 

[hwy17]

I think your offgrid explanation needs a proviso that it depends on whether they are creating their own GN bond or want the inverter to. If it was me I would still be creating my own in the panel.

 

[Markus_EG4]

And if you enable setting 26, I would imagine that it creates a bond in only one inverter regardless if you have 2 or 16 in parallel. So for offgrid use, it will create it where necessary. But if you are connected to grid, it needs to be manually changed.

@Markus_EG4 Do you think they can add an update where the bond relay opens when connected to mains?

I will check and find out. Seems to be possible but I need more people involved on this decision making.

 

[Markus_EG4]

Let's start with a snip from the EG4 6000XP manual.


What I'm getting at here, is a lot of people, including @Will Prowse in his latest video (8:03) are mistaken on how the 6000XP handles neutral and ground bonds. The inverter does NOT dynamically bond. This means that if you plan to put an cord and plug on the AC-input, then you will have problems (for example, if you plan to use this inverter in an RV). In my opinion, it's really only intended for hardwired applications, similar to the big-brother, the 18k-PV.

Neutral-ground bonds are critical in all modes of operation because it creates a fault current path so that you actually trip a breaker in the event of a ground fault. Without a neutral-ground bond, then all that happens during a ground fault is the cases of everything become live in relation to neutral and the fault is not cleared.

Double bonds are not acceptable by code or safe because it creates a parallel path for neutral currents. The current carried on the grounding conductor is know as objectionable current. NEC specifically addresses objectionable current.

The two options for successful and safe implementation are:

• Bond is either created upstream of the inverter, (in the main panel). Neutral and ground connections remain separate to the inverter (and any parallel connected inverters) and the relay in the inverter is left disabled). No cord-and-plug can be used between the main panel and the inverter. A hardwire connection is required so that the neutral and ground bond is maintained at all times, not just while plugged in.
• Bond is created in only one of the inverters, but there cannot be bonds upstream or downstream. This means if you decide to put a cord-and-plug, for example, an NEMA 14-50P (for an RV) or a 6-30P (for a generator), then you cannot plug the cord into a bonded system (for example, an RV park or generator with a bond). This would create a double-bond which is not permitted by code and cause objectionable current.

I would recommend if you plan to use these inverters in a mobile application, then you enable the bonding relay within the inverter and skip using the built-in charger/transfer switch function. When it comes time to recharge your batteries, just pick up one of the EG4 chargeverters (or 12) and use that as your input power source. Since the chargeverter is completely isolated from the inverter, the chargeverter prevents any chance of double-bonding.

@Markus_EG4 Let me know if I've missed anything here.

This is a really good explanation. Very detailed.

The only thing I would add is Grounding in general. No matter what scenario you are in Off Grid or Grid tied you always need a ground. I know being Grid tied you will have one usually but Off Grid we see so. many ungrounded systems and that is so scary because you can or will become the ground at one point.

So please always have a actual Ground no matter what.

 

[FilterGuy]

I think your offgrid explanation needs a proviso that it depends on whether they are creating their own GN bond or want the inverter to. If it was me I would still be creating my own in the panel.

I agree. Why depend on a relay when you can hard wire the bond. When I first saw that setting I wondered why it was even there.

 

[GridFree]

Can I say this is TRUE:

For all those people that run the 6000xp Off-Grid and use a Chargeverter, disable setting 26 and bond your neutrals and grounds in your (main) AC panel. The End.

Please verify so I can move on.

 

[FilterGuy]

For all those people that run the 6000xp Off-Grid and use a Chargeverter, disable setting 26 and bond your neutrals and grounds in your (main) AC panel. The End.

Yes

 

[FreebirdRV]

I am thinking I will create a plug for my shore power receptacle that has the ground and neutral bonded. When I unplug my shore power cable I will simply plug in my new plug to provide the bond, it will basically replicate the bond from the shore power connection. Thoughts?