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LV6548 et Al Neutral ground bond bad for split phase?

solarHandyman

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Hey y'all, I would love some clarification. Why does Will say on YouTube that the neutral-ground bond on various all-in-one units such as the MPP LV6548 and the new EG4 unit he just reviewed are bad when using two units to run split phase? Is the issue that you would have neutral bonded to ground in two places using two units for split phase? Doesn't 3 wire split phase only use L1, L2, and ground but not neutral anyway? Would this only be an issue in four wire, L1, L2, N and G split phase wiring schemes, such as for an electric stove?

Thanks!
 
Lol yeah electricians too different requirements in different states
 
Hey y'all, I would love some clarification. Why does Will say on YouTube that the neutral-ground bond on various all-in-one units such as the MPP LV6548 and the new EG4 unit he just reviewed are bad when using two units to run split phase? Is the issue that you would have neutral bonded to ground in two places using two units for split phase? Doesn't 3 wire split phase only use L1, L2, and ground but not neutral anyway? Would this only be an issue in four wire, L1, L2, N and G split phase wiring schemes, such as for an electric stove?

Thanks!
I thought about starting a thread which would be the reference for all N-G bonding with MPP, Growatt and now the EG4 after watching Will's video. But it would take some time to find all those golden nuggets. I was just in another thread where a member advocates using a 2 pole transfer switch.

First, if the system will be off grid only without any AC input or even a generator input, you could remove the screws and bond N-G at the service panel after the inverters. In previous threads, there was some correspondence with MPP and Growatt about the screw removal and there is a possibility it will void the warranty. My personal opinion and why I won't remove the screws is N-G bond should be at the source. My concern is if a ground fault occurred before the N-G bonded service panel after the inverters, then it most likely would not trip the breaker or blow the fuse in the inverter.

If you plan on AC input and possible generator input, then a 3 pole transfer switch will be needed and at least one inverter will need to have the ground screw remain. The reason is you can't bond N-G in the service panel after the inverters, doing so would place 2 N-G bonds in the system under AC input and objectionable current on G and most likely ground fault detection would not occur.
 
It would be a very long sticky. lol
I thought about it after watching Will's video yesterday.

I'm already envisioning everyone removing the ground screws on both inverters while wiring in AC input and thinking they "got this".

"Will removed both screws so that must be how to do it".

And then bonding N-G in the service panel after the inverters.

It will be a mess here, I think I'll finish putting the LFP in the boat and go fishing for awhile............

Some days it is just like talking to a brick wall. The EG4 thread is an example.
 
I thought about it after watching Will's video yesterday.

I'm already envisioning everyone removing the ground screws on both inverters while wiring in AC input and thinking they "got this".

"Will removed both screws so that must be how to do it".

And then bonding N-G in the service panel after the inverters.

It will be a mess here, I think I'll finish putting the LFP in the boat and go fishing for awhile............

Some days it is just like talking to a brick wall. The EG4 thread is an example.
Yup, this was also a concern of mine.
It does get very tiresome, saying the same thing over and over.
 
I actually commented on the video. In hopes of stunting some of it, before it gets here.
 
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It’s easier and safer going with a more expensive UL inverter like the big three (Schneider, Outback, Sol-Ark). That being said I have a temp Growatt system I play with but building a permanent XW Pro system.
 
Hey y'all, I would love some clarification. Why does Will say on YouTube that the neutral-ground bond on various all-in-one units such as the MPP LV6548 and the new EG4 unit he just reviewed are bad when using two units to run split phase? Is the issue that you would have neutral bonded to ground in two places using two units for split phase? Doesn't 3 wire split phase only use L1, L2, and ground but not neutral anyway? Would this only be an issue in four wire, L1, L2, N and G split phase wiring schemes, such as for an electric stove?

Thanks!
I believe there is a solution, I’m using a square D panel model QO-GP3P603 generator panel that switches the neutral. Here in Canada the code was revised and it allows bonding at each source when using a 3 pole switch on 120/240 single phase. From my understanding the codes in Canada are generally stricter then the US codes.
 
I believe there is a solution, I’m using a square D panel model QO-GP3P603 generator panel that switches the neutral. Here in Canada the code was revised and it allows bonding at each source when using a 3 pole switch on 120/240 single phase. From my understanding the codes in Canada are generally stricter then the US codes.
Same here in the US.
If the neutral is switched. That makes it a separately derived system. And N/G bonding is required at each source.
But, that's not the issue with multiple AIO's.
If each AIO bonds the N/G. Then there can be objectionable current flowing on the ground conductor. Because it's in parallel with the neutral.
The solution is to remove the bonding from all but one AIO.
 
I believe there is a solution, I’m using a square D panel model QO-GP3P603 generator panel that switches the neutral. Here in Canada the code was revised and it allows bonding at each source when using a 3 pole switch on 120/240 single phase. From my understanding the codes in Canada are generally stricter then the US codes.
If neutral is switched, here in the US then under NEC it is a separately derived system. This allows bonding at the source.

As for the N-G bond in each inverter, IMO it is considered a single source of power using a pair in split phase; therefore there is not a reason to remove the bonding screw in one unit.
 
Same here in the US.
If the neutral is switched. That makes it a separately derived system. And N/G bonding is required at each source.
But, that's not the issue with multiple AIO's.
If each AIO bonds the N/G. Then there can be objectionable current flowing on the ground conductor. Because it's in parallel with the neutral.
The solution is to remove the bonding from all but one AIO.
Thanks, makes sense, I’ll remove one bonding screw.
 
If neutral is switched, here in the US then under NEC it is a separately derived system. This allows bonding at the source.

As for the N-G bond in each inverter, IMO it is considered a single source of power using a pair in split phase; therefore there is not a reason to remove the bonding screw in one unit.
I've been following these threads for almost a year and consider you, timselectric, filterguy and ncsolarelectric experts. And you guys have different conclusions!
So Zwy, if you had 4 LV6548s, configured 2 for each leg, off-grid only, and an inverted generator that will only be used via a Generac Homelink 9854 on the other side of a NOT NG-bonded 200A main panel, would you leave the NG-bonding screw in all 4 inverters?
 
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I've been following these threads for almost a year and consider you, timselectric, filterguy and ncsolarelectric experts. And you guys have different conclusions!
So Zwy, if you had 4 LV6548s, configured 2 for each leg, off-grid only, and an inverted generator that will only be used via a Generac Homelink 9854 on the other side of a NOT NG-bonded 200A main panel, would you leave the NG-bonding screw in all 4 inverters?
Out of curiosity, why use the HomeLink? Instead of just connecting the generator to the inverters AC in.
And save yourself $600.
 
The basic concept is simple one ground point per system , these typically the PE neutral bond at thd grid entrance.

If this bond remains no other neutral shoujd be PE bonded

If a transfer switch or completely off grid operation. Occurs and the bases pe neutral bond is lost. You must establish a local ground and bond any “ generator “ neutral to it. That bond may have to be dynamically created and broken of the grid neutral pe bond reappears due to transfer switching.

That’s the golden rule. One PE neutral bond.
 
I've been following these threads for almost a year and consider you, timselectric, filterguy and ncsolarelectric experts. And you guys have different conclusions!
So Zwy, if you had 4 LV6548s, configured 2 for each leg, off-grid only, and an inverted generator that will only be used via a Generac Homelink 9854 on the other side of a NOT NG-bonded 200A main panel, would you leave the NG-bonding screw in all 4 inverters?
Yes as this is off grid only. The inverters are source, current will return to source. No need for the Homelink, simply input power to the LV6548 input side and use the internal transfer switch. The inverter generator will need a NG bond so under generator power a NG bond will exist.
 
I am wondering why more than one ground connection within the house equipment is a bad idea ?
As long as the bonds and wire making those bonds are stout enough.
Now multiple ground rods outside I see the problem with voltage potential across the poor conductivity of the earth.
But across a 6/8/10 AWG copper wire inside ????
 
Thanks for responding.
If I have any problems with solar (inverters), I will be able to switch to a propane generator, which is NG-bonded, with little down time which is a necessity.
I'll also have two 18A battery chargers for extended cloudy days.
 
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