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Open Roads Forum  >  Tech Issues

 > Wiring neutral/ground when splitting panel for MultiPlus?

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3 tons

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Posted: 10/11/19 11:15am Link  |  Quote  |  Print  |  Notify Moderator

The issue with grounds (grounds are grounds) and neutrals (neutrals are neutrals) is to keep them separated to prevent eddy currents between the two, and for the same reason it’s best to tie each into it’s own dedicated buss-bar...

enblethen

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Posted: 10/11/19 11:21am Link  |  Quote  |  Print  |  Notify Moderator

neutrals are not always common. It depends on the overall system as whether they can or cannot be tied together.
The block diagram shows separating the neutrals via the relay.


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3 tons

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Posted: 10/11/19 02:12pm Link  |  Quote  |  Print  |  Notify Moderator

enblethen wrote:

neutrals are not always common. It depends on the overall system as whether they can or cannot be tied together.
The block diagram shows separating the neutrals via the relay.


In Appendix B of the manual, it appears to me that the relay is for the purposes of bonding neutral to ground when outside power is not present...This is typical of many inverter-chargers and provided due to NEC code.

https://www.victronenergy.com/upload/documents/Manual-MultiPlus-Compact-2000-120V-EN.pdf

enblethen

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Posted: 10/11/19 02:30pm Link  |  Quote  |  Print  |  Notify Moderator

Appendix B diagram is to ground the neutral as required by the NEC is correct. That changes it from a floating neutral to one that is grounded.
The transfer relay still opens the neutral.

3 tons

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Posted: 10/11/19 03:29pm Link  |  Quote  |  Print  |  Notify Moderator

enblethen wrote:

Appendix B diagram is to ground the neutral as required by the NEC is correct. That changes it from a floating neutral to one that is grounded.
The transfer relay still opens the neutral.


I’m confused, I see no other relay in the block diagram - what am I missing?

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Posted: 10/11/19 03:47pm Link  |  Quote  |  Print  |  Notify Moderator

If this has a 50 amp internal RV transfer switch
Just install it correctly
Both sides get either inverter or shore power
your Idea
Only one leg feeding inverter and then one side of breaker panel and one leg direct to panel
Doesn't make sense to me , it might even be against NEC
Unplug shore cord, inverter is on, stick hand in panel get shocked any way
Sounds like trouble too Me

* This post was edited 10/12/19 12:05am by MrWizard *


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enblethen

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Posted: 10/11/19 04:51pm Link  |  Quote  |  Print  |  Notify Moderator

They call it a "backfeed safety relay".

joe6789

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Posted: 10/16/19 11:28am Link  |  Quote  |  Print  |  Notify Moderator

Thanks everyone for your advice. I just heard back from Victron via email. I think I understand their response but it would be helpful if anyone else could confirm I'm interpreting correctly. I had asked them whether the neutral wire needs to be branched, so that line 1 and line 2 have separate neutral wires into the breaker box and potentially even separate neutral bus bars. Sounds like the answer is "No" -- to simply run line 2 direct to the breaker box without its own separate neutral/ground, and then run line 1 through the inverter along with neutral and ground.

Victron's exact response:

Quote:

For proper current measurement and control, as well a preventing multiple return paths, it is advised to run the ground an N through the Multi without branching off to the L2 line first:

[image]

1) Only one side of the distribution panel would be powered by the inverter when not plugged in. Also no 240V inverter loads are possible with just one Multi.

2) If you only have single-phase 120V input available, make sure it is on the L1 line through the Multi. If you try to run it to the L2, the open input relay on the Multi will prevent a complete circuit. You would want it this way for charging anyway.


Does that all make sense? In the image he sent, it looks like the power source is coming from a breaker box on the right rather than a shore power cord, but I assume the answer would be the same in a shore power or generator sourced setup.

The other thing that could be troubling is his point #2. Let's say I'm using a 30A to 50A adapter cord to to plug into 30A shore power or a generator... my understanding is the the adapter provides (a smaller amount of) current into both legs of the 50A cord. So I don't think his point about the open input relay preventing a complete circuit would apply in that case, since both L1 and L2 would be receiving power.

Again, would appreciate if others have comments. This seems to be the simplest possible setup for me. It doesn't require installing a separate breaker box. I'll simply need a little junction box so I can splice and extend the L1, N, & G to the inverter and back.

Thanks,
Joe

enblethen

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Posted: 10/16/19 11:47am Link  |  Quote  |  Print  |  Notify Moderator

The drawing is too vague! Yes, it shows coming from a main disconnect through the inverter to a distribution panel.
I still say the easiest is to run your one branch circuit from the distribution panel and run it to the inverter output. Yes, you would need to run a feed from the distribution panel to the 120 volt input to the inverter.

time2roll

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Posted: 10/16/19 04:30pm Link  |  Quote  |  Print  |  Notify Moderator

Yes. This is same as we discussed earlier.
Single phase 120v will feed L1 & L2 and close the relay for normal operation on 30 amp service.


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