I have a few questions in regards to MEN (Neutral-Ground bond) for RV.
I’m designing my electrical system and i have the following question:
When using Power Assists the Multiplus-II would not do the Neutral-Ground bonding as it expecte the “shore power” to have it ? Is there any documentation about it (i read the wiring unlimited I guess that what i understood).
I have seen when in “Inverter mode” the N-G is done at the Multiplus-ii but when in “charger mode” and/or Passtrhough the N-G bound is not done.
So here what i’m thinking in my setup:
Inverter 1 (feeding AC-In to multiplus) from vehicule battery
No shore power (connection)
Multiplus-II with house battery system (separate from inverter 1)
The Inverter 1 (does not N-G Boudning)
So we must connect L/N to a RCD/GFCI Braker (better than a gfci outlet? or the same?)
Ground not connected to a busbar then to Chasis.
L connected to Multiplus AC-IN
N (from gfci) connected to “Ground” does the N-G bond then N connected to Multiplus AC-IN
G Connected to Multiplus AC-IN
My understanding is:
When the multiplus-ii is in “inverter mode” it is not using Inverter 1 N-G bound (as is offline even though AC-IN is bonded the inverter doesnt link the AC-IN N and G ? or am I wrong?).
When Inverter 1 turns on… the “Victron becomes in PowerAssits automatically if the setting is set ( i guess its stay that way once configured ?)”. Meaning it would use the 1st inverter up to let say: 10A that we can define.
if we use only 2A of load in our outlet.. the remaining 8A would charge the batteries. And then the N-G bound from the Inverter 1 would be used as the Multiplus-ii would not be doing the N-G bound via internal realy (per default config).
Am I understanding correctly? If we design it this way there should always be only 1 N-G bound even though the Inverter1 have N-G bound and Multiplus-II have N-G bound when in “inverter mode”, as long as we ensure that when inverter1 is online the mutliplus switch to PowerAssists there is always only 1 N-G bound?
Sounds like a recipie for a vehicle start problem.
The N\G bond is made at source.
If that is the grid that is easy. It is the grid.
if it is the one inverter feeding the other then it is the one behaving as grid that has the bond. (So one is inverting the other connected to it as if it was grid)
The n\g bond is only ever made in the inverter when it is inverting. So in the cascade only one (the source) will ever have the N/G bond.
Well if the Inverter does not have “AC” and “DC” connection internally and is a isolated AC/DC power inverter… and we do N-G bound in a AC Panel.
I dont see the risks?
You are kind of replying what I seems to have came to conclusion which is:
A) When Inverter 1 is in use (ex: the Multiplus is in Charge/Passthrough and/or PoweAssists mode), we need to create an N\G bond right after the inverter1(or in the inverter).
B) When Inverter 1 is not in use, (when multiplus is inverting). There should be no N\G bond prior the Multiplus which is acheived automatically when we turn off the vehicule (as giandel shutoff and multiplus would go in inverting mode). The relay of the multiplus kick in and disconnect the N/G from the AC Input/Output.
In both scenario we always have a single N\G bond and everything is safe (hopefully :D). Just trying i fully undetstand what will need to be done.
Note: We are not thinking of using shore power, else i know we would need to disconnect the N/G bond from the Inverter 1 that we made as it would be the Grid.
You might be able to try this, but it might not be correct for local laws.
You could install a small consumer unit downstream of Inverter 1, fitted with a double-pole 2-pole breaker and a neutral-ground NG bond. This unit would supply AC to the input of the Multiplus.
When the double-pole breaker is switched off, it disconnects both live and neutral, effectively isolating the NG bond from the Multiplus. Then, when the Multiplus switches to inverting mode, it automatically engages its internal NG relay, ensuring that a RCD on the output side of the Multiplus will function correctly.
Not sure why we this could potentially not be correct for local laws. As long as there is always one single N/B bond that should follow NEC i guess its not different than a single inverter that does internal N/G bond internally.
That being said, i came accross more reading and found out that some smaller inverter sometimes send 60V on both Load and 60V on Neutral (not really neutral then). That ends up that if you wire Neutral to Ground your actually sending 60V to the chasis… which would be quite bad
I beleive some people did it with that inverter so I’m assuming its doing it properly like L = 120V and Neutral the return path but, who knows maybe this device is not that way.
I"ll have to test with a multimeter to really make sure before I’m sending 60V across the chasis and break everything i guess.
If it is 60V with 2 hots then you might need to use an isolation transformer between the inverter and the multiplus to generate a true center-tapped neutral.
I just put an edit in, I meant isolation transformer, not auto transformer. If you are going to add one, you should just upgrade to a Phoenix or an inverter that allows bonding.
If you do find out if the inverter can be bonded, check with an electrician if this will work. The 2-pole breaker supply will come from the inverter, and the bond after that. Into an RCD, then the Multiplus.
Also the 2-pole might not be enough might need a four pole like this. With the 2-pole you will have to trun off both to open the link. See what other people think.
Another option i guess would be to use an “GFCI” approved inverter (that includes N-G Bond) i guess… but it does not allow Hard-Wiring. So i would need to buy a “outlet” that i could wire my 10/3 wires.
I guess that would be simpler. Just sad that i would have to sell the device that I bought.. but i guess that would make our life eaiser.
Giandel inverters provide standard 120V AC output (not dual/split).
To pass the ground tester, you can only connect the neutral and ground wires. The connection of the neutral and ground wires, that is, one end of the inverter output is connected to the shell, will bring safety hazards. Unless a leakage-proof GFCI socket is used, it can perfectly pass the problem of this ground tester and will not cause safety problems.
You dont need to hardwire it set it up like a generator input. I have modified this diagram, you might also be able to use a 3 pole breaker and break the ground input and also the NE bond.
