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flugs asked

Any risk for inbuilt motorhome DC electronics from grounding and neutral bounding

Bonjour,

It might be a dump questions and probably shows my (quite) limited knowledge and experience.

I want to install a Multiplus II (12/3000) into my motorhome and I understood that I will need to protect the AC out 1 with a RCD and that this will only work due to the neutral bounding (PEN).

I also have a hydraulic lifting system, which means that the motorhome could have a connection to real earth when these are deployed (not sure if this is important or changes anything).

My question: When bounding "earth" and neutral in case I'm not connected to the grid, and with the motorhome's ground being the chassis/frame, wouldn't this interfere or couldn't this even be dangerous for the car's electronics (motor management, etc, which are using the DC ground, which is also connected to the chassis). What will be the effect on the DC negative when having the AC neutral connected to it?

I suppose there is no risk, as I have not found any comments either in this forum or via google or in the documentation from Victron, but I would like to understand so I can convince myself that there is no risk.

I would appreciate if somebody could explain this to me with easy words.

Thanks in advance,

Kind regards

Multiplus-IIGrounding
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kevgermany answered ·

Vehicle tyres are conductive, your motorhome chassis is always connected to a real ground.

When there's no AC input neutral and earth are automatically bonded by the multiplus, so are at zero volts. AC line voltage varies with its midpoint being held to the same zero voltage as earth/neutral.

When there is grid AC input earth is provided by the input cable, neutral also. Both are at zero volts in respect to each other and in reference to real ground.

DC positive and AC line are not and should never be connected, this would cause the damage you fear.

The bonding simply ensures that there is no voltage difference between neutral and earth. If there is, the breakers will trip before damage occurs or someone gets a shock.


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flugs avatar image flugs commented ·

Thanks a lot kevgermany. This brings some light into the dark. Enjoy your weekend

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