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Relying on earth rod in off grid?


Some thoughts about building a three phase system with multiplus 2 with off grid capability. Is there some way of confirming the connection to earth when in off grid (the multi disconnects L and N on AC in, correct?)

Seeing as I don’t want to risk sending a current back to the grid from the multi when using battery power, I cannot connect the AC out to the grids neutral or PEN. When in off grid mode the idea is to use a grounding rod as the neutral point and earth (effectively creating a TN-C from the multis when in off grid)?

How do I eliminate the risk of losing my neutral point (connection to earthrod is lost somehow, or the resistance to earth is to high) and thereby risking damaging electronics connected if the loads are uneven over the three phases (0-400V on regular outlets)?

Has anyone experienced problems with this? Is there some kind of module that could be installed that measures the ground resistance continuously and breaks the AC out if ground is lost?

calle asked
delf67 commented ·

3 Answers

Multiplus-II and grounding best practices

I'm using a Multiplus-II 5000 at home and want to make sure that the grounding setup is correct.

AC-in is connected to the grid (which only provides phase/neutral so I connected the PE line directly to the house's ground, as well as the chassis)

AC Out 1, until now, is my whole electrical network so it remained connected to the house's ground without any changes.

I want to add new equipment on AC Out 2 and I'm wondering how I should ground that new line. Should I connect it to the AC Out 2's PE line? Directly to the house's ground with AC-in/chassis/... ? Are all the grounds inside the multiplus connected together in which case it doesn't matter where I connect it?

zeron asked
sharpener edited ·

2 Answers

Smart Solar MPPT 100/20 12V rv grounding

Hi all,

For a mobile installation (rv) with this model (20A) the manual says :

Chassis grounding (only for the 20A model)

A separate ground path for the chassis ground is permitted because the chassis is isolated from the positive and the negative terminals.

Sorry, but when a manual tells me that it is allowed but not required, it confuses me...

Should I connect the ground of the controller to the rv chassis or to the lynx busbar ?

Thank you.

nvs asked
donmacn answered ·

3 Answers

Connecting Ground Screw on 100/30

I'm building a teardrop trailer and just installed a Victron 100/30 solar controller. I'm asking where the ground screw should be connected to? I'm using a Blue Seas bus bar where the battery + and - go to, the solar panels + and - go to and the battery charger go to. I'm wondering if the ground screw on the solar controller can go to the neg bus bar, as well? Thank you. Please ask for any additional info. Appreciate the help.

teardropper asked
Kevin Windrem commented ·

2 Answers

MPPT GFPD Requirements and DC2DC Current Ratings

Hello! I am building out a van system and have a 3 seperate questions after reading the manuals for an MPPT charger and a DC2DC charger:

1) SmartSolar MPPT 100/50 manual states in section 3.2 that the NEC requires a GFPD between the system negative and earth ground. Is this referring to placing a GFPD between the MPPT chassis negative terminal and my earth system ground? Using a GFPD device on your DC circuits is new to me. Can someone please explain to me practically what situations this would protect you from? Additionally, from my reading it appears that the NEC code chapter 6 has an exemption for mobile solar arrays here:
"690.41System Grounding: Exception : PV arrays with not more than two PV source circuits and with all PV system dc circuits not on or in buildings shall be permitted without ground-fault protection where solidly grounded".

I will only have a single PV-source circuit.

2) Orion-Tr Smart DC-DC Charger Non-Isolated 12/12 - 30A: I am trying to size the wires and breakers for this unit, but cannot seem to find how much current this unit will draw under max normal operating conditions. I guess this is where I lack a fundamental knowledge of how a DC-DC converter works. Simply put, how much amperage can this unit draw from the batteries on my van? It is not listed in the data sheet. Is it a function of the max output current or power listed? Max output power is listed as 430W / 12V = ~35.8A max that the unit will draw from my van battery? Or should I size my breakers to the listed output short circuit current of 60A?

3) Can you ground your DC system and your AC inverter through the same negative busbar, which is connected to the same earth ground (vehicle chassis)? I have not had to consider grounding DC and AC currents to the same spot before.

Thank you so much for the help!

vanbuild117 asked
Alexandra answered ·

1 Answer

Battery negative to earth or not
Battery grounding is not shown in most current drawings. 
But the "Wiring unlimited" PDF shows and describes very precisely how the battery 
is included in the grounding of the system. 
Since Victron always refers to the "Wiring unlimited" document and refers to it, 
I wanted to know exactly whether the battery in a system with excess feed 
and 48 volt battery storage should be connected to the grounding bar or not. 
If so, I would like to know the benefits. 


Thanks for the answer

der-neue-hier asked
Alexandra answered ·

1 Answer

Grounding the Neutral of the Battery

We have a 3-phase ESS 5KVA multiplus-ll inverter installed it's using a Freedom Won 53V Battery.

The connection is battery to Bus-Bars. Bus-Bar to circuit breakers to inverters

My question is, must the neutral of the battery be grounded also?

Lindsay asked
der-neue-hier answered ·

2 Answers

"Ground Relay" setting, on or off?

Hello, I have a Multiplus 2000/12/80. The Ground Relay setting is on by default. Based on my reading it looks like I should turn it off. I don't have a ground relay wire hooked up and I didn't buy an autotransformer. All I have hooked up to my multiplus is the battery, chassis ground, shore power, AC, and battery temperature cable. Am I missing anything or should this be turned off? Would having it turned on have caused any issues?

Thanks for the help!

kaplan78 asked
sharpidea answered ·

9 Answers

Multiplus 12/3000/120-50 Ideal Grounding on Travel Trailer

I've spent quite a bit of time researching this question, in the Wiring Unlimited document, along with the Multiplus manual and a multitude of forum postings. I realize some elements of the question are largely redundant so I will try and be as specific as possible. This installation is for a personal RV, and although I'm not a licensed electrician I have done quite a bit of high voltage electrical work, and as a computer scientist have had some exposure to electrical engineering principles and issues when working with microcontrollers, etc, though most of my work does not involve machinery or process automation. I'm by no means an expert, however.

I'm working to complete an installation of 2xMultiplus 12/3000/120-50 inverters connected to a 6x100AH Battleborn battery bank in parallel configuration. I also have a SmartSolar 150/85 MPPT controller connected to 7x195Watt PV panels mounted on the roof. The Multiplus units are in a split phase parallel configuration. Proper size wiring and current protection devices (breakers and fuses) on both the A/C and DC side are installed and various points(E.G. pre inverter A/C breaker, post PV combiner to MPPT controller, post MPPT controller to battery bank, post battery bank pre inverter, pre trailer existing wiring connection, post inverter A/C to trailer, etc). Properly sized wiring is used based on the current protection devices in place and maximum intended sustained amperage taking into account insulation rating, conduit fill rules (where applicable), etc.

At this juncture I have completed the majority of the installation on the system but have come to a question on proper ground application. Currently all equipment functions without grounding the equipment separately to the chassis(although I have full intention of doing so), and I have tested the system in excess of 250amps continuous DC flow to the inverters for extended periods of time(E.G. by turning on the A/C, electric hot water heater, etc). After working through a number of configuration "tuning" issues, I'm happy with the results, although an added element of safety is left dangling out there.

With that in mind, I believe the following is accurate:

1) Each Multiplus should be separately grounded to the chassis using a conductor of equal size to the conductors used in DC +- in the inverter. In my case 4/0 wire with 105c insulation.

2) The Solar MPPT controller should be grounded to the chassis, again with the same principle outlined in 1 regarding wire sizing.

In both 1 and 2, it would be alternatively acceptable to utilize a wire size equal to the acceptable size requirements for the current protection(e.g. for the battery bank a 300AMP fuse is used) device.

This brings me to my question(s):

Currently the negative and positive leads running to/from the inverters are connected to BusBars rated for 600A each. The positive side, prior to reaching the bus bars from the battery bank is fused, and then runs to a disconnect, then to the bus bar. The negative side, through a shunt and then straight to the BusBar.

One of the terminals on each BusBar runs off and connects to the main trailer wiring via the terminals where the previous manufacturer supplied batteries resided and then into the main trailer DC supply disconnect. This minimized the amount of rewiring needed to tie into the existing DC wiring. The positive side leading to the trailer manufacturer dc wiring is fused prior to reaching the existing trailer wiring system.

The existing trailer appears to have ran a frame chassis DC connection from the negative side of the DC wiring. Should I disconnect this and replace it with a larger 4/0 wire from the battery bank bus bar? Is it acceptable to leave it, and run an additional negative wire from the BusBar directly to the chassis(near the existing ground bar on the trailer)? Would/Could this create a ground loop/other situation with multiple DC paths to the chassis ?

Additionally, since the Multiplus requires a ground, should I route that to the negative BusBar, instead of a separate ground out to the chassis, and then use the larger ground noted above? The same applying to the MPPT controller. Similar to this:

In the aforementioned diagram, it would appear all negative and ground connections are terminated on the same negative busbar, and then a single chassis ground is ran to the frame. If that is the more suitable way to approach it, would it be necessary to disconnect the existing DC negative to chassis run the manufacturer installed(I would think so)? How would energizing the inverter chassis with high voltage A/C impact the DC negative connected equipment in the case of a short to the inverter housing using a common busbar scenario(or for that matter into the chassis) ?

I'm trying to determine the most ideal path forward to ensure safety and minimize complexity. The wiring space is extremely constrained as well. Any recommendations are much appreciated.

Thanks in advance for any thoughts.


chrisk asked
rubicon commented ·

3 Answers

Raccordement à la terre Phoenix 1200VA


Je souhaiterais savoir comment raccorder efficacement à la terre un convertisseur Phoenix 1200VA.

J'ai lu attentivement le mode d'emploi et parcouru pas mal de forums.

Ma maison est raccordée au réseau électrique public (schéma de terre TT) et dispose d'une assez bonne prise de terre (résistance = 6,8 ohm).

Le convertisseur sera utilisé dans une pièce annexe pour alimenter notamment un frigo durant la nuit (les batteries étant rechargées la journée grâce à des panneaux solaires). Je ne souhaite pas que quelqu'un puisse s'électrocuter en touchant un frigo si jamais celui-ci présentait un défaut d'isolation.

Donc, au moment où le convertisseur fonctionnera, le réseau électrique de la maison sera également en fonction et donc connecté au réseau public. D'autres appareils dans la pièce seront eux connectés au réseau.

Le manuel indique : "Cet appareil est un produit de classe de sécurité I (livré avec une borne de mise à la terre de protection). Le châssis doit être mis à la masse.".

Et plus loin, un schéma indique la procédure à suivre.

En suivant le manuel, si j'ai bien compris, je dois connecter le neutre à la masse/terre à l'aide du connecteur FJ2. Je dois ensuite raccorder le châssis du convertisseur à la terre de ma maison à l'aide d'un câble de diamètre approprié.

Et c'est là que tout s'embrouille dans ma tête. Etant raccordé au réseau, la terre de ma maison est liée au neutre du distributeur (via le transfo du quartier). Cela ne va-t-il pas poser un problème si cette même terre est en même temps liée au neutre du convertisseur? Comment vont réagir mes disjoncteurs différentiels en cas de fuite dans cette situation?

Je ne suis pas un expert en électricité. Mais est-ce qu'une même prise de terre peut servir à protéger efficacement deux sources de courant en même temps (le réseau public et le convertisseur)?

D'avance merci pour vos réponses et éclaircissements!

ludowan asked
arnaud-lasseron answered ·

4 Answers

Negatively Ground Victron System

We are wiring up the system as per the below wiring diagram and would like some assistance with wiring it to be negative 48V,
From our research you connect the positive connection from the battery or we could use the positive from the distributor to a common point which all the Victron casings links to, is this correct?
Then a connection is taken from the central point to a ground stake.

@Daniel - I've read your grounding responses, can you assist with this one?


stephenv asked
shaneyake commented ·

1 Answer

Multiplus 2 Shore power AC In and Out ground question


New install of full Victron system, Original shore power in has only Active and Neutral, going into RCD and then into rest vans reciprocal sockets throughout the van.

I have replaced RCD with new one and added another, so taking shore in thru RCD and then to Multiplus 2, then AC Out 1 and back to RCD and then into Vans 240v system. Now there is no Earth wire from Shore in, all the earths are connected thru all the power points (receptacles) and then there is a wire thru the floor connected to the chassis.. Or maybe the Earth on the Shore power external socket/input goes to the recepticals from there.. and then is connected to every powerpoint and the chassis.. so maybe its as simple as running a wire from chassis to AC In Earth on the multi to link it all up..

I am yet to actually wire in the ac in and out wires on the Multi and turn on. until this issue is understood.

I have run a 00 cable from the Multiplus 2 earth stud into the Lynx distributor and will run a 00 cable from Lynx thru the floor onto the van's chassis, all other solar controllers and DCDC components will be chassis linked to the Lynx..

My main question, is it ok to only have Neutral and Active run into the AC IN and AC Out of the Multiplus, this van is 2008 era and in Australia so earths were run on all the outlet's side of things.. and was it the right idea to had an extra RCD for the input and output from shore and out of Multiplus..

EDIT: pulled out the Vans Shore external socket and the earth is connected into the rest of the vans recepticals..


camo88 asked
klim8skeptic commented ·

0 Answers

Positive ground on Quattro

Are there any issues with grounding the positive side of the 48v battery system on a Quattro or MTTP controller. I have some telco equipment that requires a positive ground to work.


derek asked
wjf commented ·

1 Answer

Grounding Battery's Neutral in ESS system

In Wiring Unlimited by Victron the ESS system's battery is grounded from the neutral (refer to image below)


Now I have a 3-phase ESS system using a Freedom Won 53V battery due to conflicting opinions, I'm not sure if I must ground the battery's neutral.

My connection is from Battery to Bus-Bars, Bus-Bar to circuit Breakers, Circuit Breakers to inverters.


Lindsay asked
nickdb answered ·

1 Answer

Multiplus-II GX and 230v AC with no neutral (still distributed in some part of Italy)

It Italy there still areas where distributor provide 230v AC without neutral (based on distribution of 3-phase 230v with no neutral)

In this situation, to connect the AC to a Multiplus-II GX in with no neutral it is enough to disable ground relay? (and connecting the ground to device chassis)

There is a specific procedure to do so?

Kind Regards,


blackstar asked
tokke commented ·

1 Answer

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