Victron. Want to hire an expert. Around SE.

HRTKD said:

smoothJoey, thanks for posting that video. I understand more than I did before.

It makes me wonder what I'll see when I open up a pedestal at a campground. Would the pedestal be considered a subpanel and therefore should not have ground bonded to neutral?

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Yes the pedestal is a subpanel and the n/g bond will be at the service entrance.

He must have heard us.

CamoGreg said:

I looked over Barry's photos again and still can't tell if he has a cat6 data link cable between the multis.

Pretty thorough comment on dual multiplus RV setups from VE community:

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Do you think the data-link between the units somehow addresses the objectionable current problem?
Maybe it does but I don't see how.
@sunshine_eggo explained to me that the diagram he showed has some jiggery pokery using a residual current device and a breaker on the neutral to address the issue.
That indicates that its a real issue and the solution presented is euro-centric.
I would like to see a solution for the typical north American topo, preferably without depending on a GFCI.
At ~17:30 in the video it talks about how parallel n/g bonds effect a short circuit.
I had figured on the effects on a ground fault but didn't think about how it pertains to the short circuit.
Its worse than I thought.

smoothJoey said:

Do you think the data-link between the units somehow addresses the objectionable current problem?
Maybe it does but I don't see how.
@sunshine_eggo explained to me that the diagram he showed has some jiggery pokery using a residual current device and a breaker on the neutral to address the issue.
That indicuates that its a real issue and the solution presented is euro-centric.
I would like to see a solution for the typical north American topo, preferably without depending on a GFCI.
At ~17:30 in the video it talks about how parallel n/g bonds effect a short circuit.
I had figured on the effects on a ground fault but didn't think about how it pertains to the short circuit.
Its worse than I thought.

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My thought is that when a data link is involved it allows one inverter to be master and the other a slave.
I would suspect (don't know for sure) that the master would apply the internal N-G bond relay depending if shore power is connected or not. And prohibit the slave from bonding either way.

CamoGreg said:

My thought is that when a data link is involved it allows one inverter to be master and the other a slave.
I would suspect (don't know for sure) that the master would apply the internal N-G bond relay depending if shore power is connected or not. And prohibit the slave from bonding either way.

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I don't see how that would work.
The current has to return to its origin to clear a fault.
UPDATE: On second thought I can see how it would work.

smoothJoey said:

I don't see how that would work.
The current has to return to its origin to clear a fault.

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I'm just thinking out loud. I don't know any of this for sure.

But the neutrals of both multis are likely joined at the junction box. The multis are extremely fast. They can detect power outage and be online so fast digital clocks don't even flicker. I don't know what Victron is able to do via the link.

I just know that for most dual setups that data link is critical.

CamoGreg said:

I'm just thinking out loud. I don't know any of this for sure.

But the neutrals of both multis are likely joined at the junction box. The multis are extremely fast. They can detect power outage and be online so fast digital clocks don't even flicker. I don't know what Victron is able to do via the link.

I just know that for most dual setups that data link is critical.

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If the datalink solved the problem I don't think the diagram we have seen would need all the jiggery pokery.

smoothJoey said:

If the datalink solved the problem I don't think the diagram we have seen would need all the jiggery pokery.

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Yet another jiggery pokery reference. Keep that up and I'll have no choice but to suspect some UK lineage.

Man, I really want to ignore this shit. Grounding/Bonding always gives me a headache.

smoothJoey said:

When the inverters are inverter mode I suspect each one will have a neutral/ground bond.

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True. Victrons function as follows:

When connected to an AC source, N-G bond is opened at the inverter. They rely on the N-G bond of the AC input source.

When inverting, each inverter will have N-G bond.

The N-G bonding relays are controllable, i.e., one can select to completely disable the N-G bond in the inverter.

In this case, if both inverters have NO N-G bond, and the only N-G bond is at the main panel, then I think this problem goes away. Would you concur?

sunshine_eggo said:

Man, I really want to ignore this shit. Grounding/Bonding always gives me a headache.



True. Victrons function as follows:

When connected to an AC source, N-G bond is opened at the inverter. They rely on the N-G bond of the AC input source.

When inverting, each inverter will have N-G bond.

The N-G bonding relays are controllable, i.e., one can select to completely disable the N-G bond in the inverter.

In this case, if both inverters have NO N-G bond, and the only N-G bond is at the main panel, then I think this problem goes away. Would you concur?

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If both the inverters are inverter mode and they don't bond n to g, where is the n/g bond?
Sorry bout the headache.

smoothJoey said:

If both the inverters are inverter mode and they don't bond n to g, where is the n/g bond?
Sorry bout the headache.

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It would have to be at the main panel. My concern is with a fixed installation.

There is another set of rules for "separately derived systems" which kinda seems to apply to inverters (generators, UPS systems and transformers are mentioned). There also appears to be a distinction between objectionable current on the load vs. source side of a circuit.

I think until one of us (not it) fully digests the NEC and truly understands what applies to where and how, it's best left to the professionals.

This is my understanding of how it works.

The 120v outputs of both inverters are tied into a panel, so both neutrals and both grounds will be tied together.

If generator or shore power is on, the N-G bond is at the generator or the shore power and the Victron inverters open the relay.

If the Multiplus is inverting then it bonds the N-G at the master unit.

If you have more than one Multiplus in either parallel configuration or Split-Phase - there will be a data cable connection that will tell the Master unit to Bond and the other units to not bond. (Still only one bond).

If you have two units not connected by a data cable, there is a setting in the software so you can program one unit to not bond. Then as long as both units are running or the main unit is running - no problems. You could have a problem if you turned off the main unit (the one that automatically bonds) and turned on the other unit - then you would not have the bond.

This is probably why Victron does not recommend running two units that are not in parallel or split phase.

In reality in an RV you would want to have them setup as split phase. If on 50a shore, both chargers will run charging the batteries up faster.

If on 15a or 30a shore (or if the generator only delivers single phase). The main Multiplus will charge the batteries- because it’s power in in-sync. The other inverter will ignore the incoming power and will invert from the batteries. This keeping the split phase power in the rig.

(This is exactly how the Multiplus II works - it is just in one 300w unit instead of two 3000w units. You could get almost the same power by paralleling two Multiplus II’s - except on a 50a circuit all the charging would be on one leg).

Even though the OP (original poster) doesn’t need split phase this would probably be the best way of handling everything. Then all the data will also show up correctly on a Cerbo.

CamoGreg said:

I looked over Barry's photos again and still can't tell if he has a cat6 data link cable between the multis.

Pretty thorough comment on dual multiplus RV setups from VE community:

Click to expand...

Thank you, I sent a copy of this to Justin, and he was reviewing my pictures and hopefully will decide to look everything over and do whatever add-ons or adjusting he wants.
Like I told him, you dont need to ask me; just do what you want, and I will write a check.
Problem with the professionals like him they are so busy I can only hope he decides to do the job.
Maybe his friend Steve on here can pull some strings ?

sunshine_eggo said:

It would have to be at the main panel. My concern is with a fixed installation.

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That would be work as long as you never attach to shore power via pedestal.

sunshine_eggo said:

I think until one of us (not it) fully digests the NEC and truly understands what applies to where and how, it's best left to the professionals.

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I'm going to keep thinking about it.

Rocketman said:

If you have more than one Multiplus in either parallel configuration or Split-Phase - there will be a data cable connection that will tell the Master unit to Bond and the other units to not bond. (Still only one bond).

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I don't see why that wouldn't work.
I updated the drawing.

Rocketman said:

This is my understanding of how it works.

The 120v outputs of both inverters are tied into a panel, so both neutrals and both grounds will be tied together.

If generator or shore power is on, the N-G bond is at the generator or the shore power and the Victron inverters open the relay.

If the Multiplus is inverting then it bonds the N-G at the master unit.

If you have more than one Multiplus in either parallel configuration or Split-Phase - there will be a data cable connection that will tell the Master unit to Bond and the other units to not bond. (Still only one bond).

If you have two units not connected by a data cable, there is a setting in the software so you can program one unit to not bond. Then as long as both units are running or the main unit is running - no problems. You could have a problem if you turned off the main unit (the one that automatically bonds) and turned on the other unit - then you would not have the bond.

Click to expand...

Are you sure about this? Can you provide a reference? I found a reference that if the N-G bond is open on the second unit, L2 output is disabled.

Thanks, Steve and the rest of you, for bringing up concerns.
I have an appointment with Justin at Panels Up Solar in Gulfport, MS, on the 28th of this month for Justin to do whatever he wants.

We would love a follow up once your installation is complete.

sunshine_eggo said:

We would love a follow up once your installation is complete.

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I will for sure, as im guessing this will not be cheap, but it will be better and safer when he is done.

The best part is if you have him start a system from scratch, he uses all Victron stuff, so as the distributor said, he knows his stuff.
I made it clear do what you want and add anything I need; no need to ask me, just do it.

Im like the British when it comes to electrical, I never learned it, and dont have a clue.
Im good at changing light bulbs!!!

Take good before and after pictures!