MPP Solar LV1012 N-G Bond

[JAS]

Jumper the input neutral and output neutral together.
Problem solved.

I've seen that solution proposed elsewhere and even in this thread it is questioned as to whether that is safe...

I'm having a hard time wrapping my head around how that would solve it also? What if my AC input is disconnected? Wouldn't I be back to the same problem?

 

[timselectric]

Only if the input is physically disconnected.

 

[timselectric]

It solves the issue by using the inputs N/G bond. For all modes.

 

[JAS]

So I'm still concerned that the unit is "trying" to bond N/G and something is just not right with the unit. What should I expect to see between terminals on a true floating neutral?

 

[timselectric]

Anything between 1 and 119v.

 

[timselectric]

With no electrical connection, you are just reading potential. It's usually around half the nominal voltage. But, could be anything.

 

[12VoltInstalls]

seen that solution proposed elsewhere and even in this thread it is questioned as to whether that is safe...

It may be unsafe in some circumstances. Not a carte blanche statement.

Wouldn't I be back to the same problem?

It solves the issue by using the inputs N/G bond. For all modes.

Mine has output G and N as well as the incoming G all connected with both incoming grid and inverter output unplugged.
With grid and output plugged back in, any L to any G or N is 120V.

I was not able to prove if it actually transfers G from bonded to incoming grid bare/green.

 

[timselectric]

Every situation is different. I am only giving a solution for this situation. This may or may not be a solution for other situations.

 

[Zwy]

So with no load on, I get slightly better...

H-N = 120v
H-G = 110v
N-G = 10v

Is this "normal" or do I have a faulty unit?

You have a parallel path somewhere. Note the voltage potential of 10V on G when checking H-G, which also shows up in N-G.

If you have no wires connected to outputs, then yes, you might have a defective unit. But I'm assuming you have outputs connected so you would have to look downstream.

Did you earth the unit by hooking to a ground rod?

 

[JAS]

You have a parallel path somewhere. Note the voltage potential of 10V on G when checking H-G, which also shows up in N-G.

If you have no wires connected to outputs, then yes, you might have a defective unit. But I'm assuming you have outputs connected so you would have to look downstream.

Did you earth the unit by hooking to a ground rod?

Other than the powerstrip that I have wired into the AC output, I had no outputs connected on that test.

For this unit there is no grounding screw or lug provided for connecting to a grounding rod (manual also does not state anything about grounding). In addition, my receptacle tester lights show "correct wiring". (no open ground, etc.) ?‍

 

[JAS]

BTW: I heard back from Ian at Watts247 and he also said to jumper the neutrals. My concern now with this unit is why did MPP Solar support tell me it bonds N/G? Do I have a faulty unit or do they not know their own product???

 

[JAS]

Mine has output G and N as well as the incoming G all connected with both incoming grid and inverter output unplugged.

Confused a bit about what you've done here... Are you saying you tied both Grounds of Input and Output together along with the Neutral of the Output? (IE: did not insert the wires into the terminals?)

If so, that is obviously bonding N/G at the Inverter. But, in my case, I have N/G already bonded from my service panel coming into the AC Input. Wouldn't that be a problem?

 

[timselectric]

If so, that is obviously bonding N/G at the Inverter. But, in my case, I have N/G already bonded from my service panel coming into the AC Input. Wouldn't that be a problem?

Yes
N/g bonding can only happen once.

 

[timselectric]

My concern now with this unit is why did MPP Solar support tell me it bonds N/G? Do I have a faulty unit or do they not know their own product???

Sadly, it could be either of these.

 

[JAS]

Sadly, it could be either of these.

Ian's response did not give me a lot of confidence either... My unit was just purchased in the last 6 months and Ian did not have them sitting on the shelf for years. So unless MPP had it sitting on a shelf for quite a while before shipping to him, you would think it would match any changes they made???

---------- Forwarded message ---------
From: <sales@watts247.com>
Date: Mon, Apr 11, 2022 at 10:58 AM
Subject: Re[2]: Strange voltage reading on 1012LV-MS
To: (removed)


They may have snuck in an update without telling us. I tested them about 2 years ago, but maybe they changed something without our knowledge
I will ask them a blanket question on all models now
Tks
Ian

 

[JAS]

Back to the OP, @thetimbo ...

Sorry for derailing your thread

I guess you're going to have to do your own testing and let us know how your unit behaves...

 

[12VoltInstalls]

Mine has output G and N as well as the incoming G all connected with both incoming grid and inverter output unplugged.

This is mine^

concern now with this unit is why did MPP Solar support tell me it bonds N/G? Do I have a faulty unit or do they not know their own product

As above- mine seems to in the condition described

Are you saying you tied both Grounds of Input and Output together along with the Neutral of the Output? (IE: did not insert the wires into the terminals?)

NO. That is out of the box conditions

so, that is obviously bonding N/G at the Inverter.

it appears that way

in my case, I have N/G already bonded from my service panel coming into the AC Input. Wouldn't that be a problem?

you would be correct as stated:

bonding can only happen once.

I guess you're going to have to do your own testing and let us know how your unit behaves...

My meter is ‘capable’ of doing ohms on hot conductors without blowing up, but that’s irrelevant cuz alternating current messes with readings. My unit is barely a month or so since I received it and it appears to be bonded in ‘off grid’ conditions.
I haven’t been able to verify that internal bond opens when grid power is connected. It depends on how many conductors are switched w/ the internal switch.

If internal G is not being disconnected when grid is connected then that is undesirable.

 

[timselectric]

If internal G is not being disconnected when grid is connected then that is undesirable

It should be continuously connected, at all times.
I think that you meant to say N.
Or N/G bond.

 

[JAS]

NO. That is out of the box conditions

Oh... . Do you have easy enough access to post a picture of that? I'll do the same of mine once I get the panel off (since I wanted to test voltage right at the terminals anyway)

 

[12VoltInstalls]

It should be continuously connected, at all times.
I think that you meant to say N.
Or N/G bond.

Ya, N/G bond. Sorry, I didn’t use enough words.
To be ‘right’ the N-G bond present internal to unit while disconnected from all incoming 120VAC should the open when grid is connected to take on the grid entrance panel’s N/G bond so as to not have two N-G bonds.

I’m not sure it does that. Not sure if I could tell if I pulled the cover to find the relays either. So little time in my life