Hi, this has been discussed, but I have found no definitive answer. Multiplus II, as described in manual, is capable of TN networks. So I understand, that with proper wiring it can work both in TN-S and TN-C. As expected, grid codes allows in some countries “AC Neutral path externally joined”, which is a must for TN-C network. My gridcode “Czech PPDS A1/A2” does not limit functionality to TN-S, at least I have found nothing such in whole approval document. So - Can I use Multiplus II in TN-C with AC Neutral path externally joined with gridcode Czech PPDS A1/A2? Is there any Victron document forbidding this? Of course, RCCB required for safety can be added at final distribution place after TN-C to TN-C-S changeover.
I don’t know of any document preventing this. There is also the configuration setting for externally bonded neutrals.
TN-C supply is fine upstream of the inverter
But you must convert to TN-C-S / TN-S before the MultiPlus AC-in. The PE/N bonding and RCD strategy must comply at the distribution level, not inside the inverter wiring scheme. Regarding “externally joined neutral path”: that is generally a supply-side PEN arrangement, and Victron does not support running the inverter as part of a PEN conductor system through its terminals.
Also important: RCCB placement only works correctly if N and PE are properly separated downstream of the point of separation. If PEN is still present at the inverter terminals, RCD operation becomes unpredictable or invalid depending on fault paths. Bottom line: Yes, TN-C systems can be used with MultiPlus-II installations, but only after conversion to TN-S/TN-C-S before the inverter AC terminals. There is no Victron approval path for running the inverter as part of a TN-C PEN conductor system.
You are both right. Inverter cannot be part of TN-C PEN wire, as PEN must be uninterruptedly connected outside inverter, if TN-C is used. However Victron does not forbid it anywhere, claiming Multiplus is for any TN network. So I’m in shadows as before. Remember, RCCB is for user protection, not Multiplus protection, so TN-C with RCCB in every socket still can be legal (athough not practical).
The MultiPlus-II is not suitable for installation within a TN-C system where a PEN conductor is present at the inverter terminals.
Per IEC 60364 principles, the PEN conductor must remain continuous and is not permitted to be switched or interrupted. The MultiPlus-II internal transfer switch includes neutral switching, which is incompatible with PEN usage at the device level.
Therefore:
TN-C is permitted only upstream of the main earthing terminal (MET)
A TN-C-S conversion must occur before the inverter AC terminals
The inverter must be supplied and operate as a TN-S system
RCD functionality is only valid once N and PE are properly separated
There is no Victron documentation explicitly certifying operation as part of a TN-C PEN path, and system design must follow local wiring regulations (IEC 60364 or national equivalent such as PPDS A1/A2).
So do you habe a Problem in your Installation with that, or is it just a theoretical discussion?
In my option, if you have a TN-C grid, you should anyway transform it to a TN-C-S.
You can do it without an earth rod (in dependece on the line impedance). But better you habe a separate earth rod installed as well.
Then you have no Problem with any RCDs or with the Multiplus.
It is a real issue. There is TN-C supply to the house, where 30 meters far from the house distributor there is fire safe place for Multipluses & batteries (!) to be installed. However, replacing 4 wires to 5 wires for the Multiplus-distributor connection through whole house means real (and unnecessary) problem. In distributor, there is split point of TN-C-S and the rest of installation is normal TN-S.
Yes, exactly this is the schematic I want to realize. It is your own or is it taken from some Victron recommendation? Thanks
PPDS A1/A2 talks about lots of things, but does not specify TN-C nor TN-S. That’s why I’m looking for confirmation.
Its my own, the system was planned but not yet installed, but i have no worries that the externally joined neutral path will be an issue. On the load side the TN-C will also be split to TN-S in the fuse boxes, but i have not drawn this since its not the scope of the MultiPlus install