Faut-il relier un busbar Lynx Power in à la terre (PE) de la maison?

Been scratching my head over this one for a while now and thought I'd ask here before I do something I regret.

I'm running a Victron setup in my static caravan — MultiPlus-II, Lynx Power In busbar, Cerbo GX, the whole lot. Everything communicates over VE.CAN and I've got it mostly sorted, but I keep going back and forth on one thing: should the Lynx Power In be connected to the caravan's PE (protective earth)?

The Victron documentation isn't exactly crystal clear on this for standalone off-grid installs. In a house or van with a proper incoming mains connection it seems more obvious, but in a static caravan that's sometimes grid-tied and sometimes running purely off solar and a 48V LiFePO4 bank (Fogstar Drift cells), I genuinely don't know what the correct answer is.

A few specific questions:

• Does the busbar chassis need a PE connection for safety, or is bonding the battery negative sufficient?
• Does it change depending on whether the MultiPlus is in island mode vs. passthrough?
• Is there a risk of creating a ground loop if I earth both the busbar and the inverter chassis separately?

I've seen conflicting advice on various forums and the IET guidance on off-grid installations doesn't seem to cover this scenario directly.

Anyone here running a similar Victron-based system who's worked through this? Would love to know what approach you've taken and whether an NICEIC-registered sparky signed it off or whether it was self-certified under Part P.

@JennyCole the Lynx Power In is a DC busbar — it doesn't get connected to your house PE directly. Your PE bonding happens at the MultiPlus-II's chassis earth terminal, which then ties back to your site's main earth point.

What does matter is your DC negative — on a floating system (typical for off-grid), the negative busbar stays isolated from PE. If you're grid-tied or have a MultiPlus in a TN-S setup, Victron's own wiring guidelines specify a single chassis-to-negative bond point, usually at the inverter/charger itself.

I'd strongly recommend downloading Victron's Wiring Unlimited PDF — it covers this exact scenario with diagrams. Running a shepherd's hut setup myself, got caught out initially by assuming DC negative and PE were interchangeable. They're not, and confusing them can cause ground loops or worse, nuisance RCD tripping on your site supply.

Hey @JennyCole, just to add to what @JYT_Solar said — worth remembering that your MultiPlus-II handles the AC side PE bonding automatically when it's in inverter mode (it internally connects neutral to PE via a relay). So don't go doubling up on that thinking you're doing yourself a favour, as you can end up with issues.

For the DC side, your battery negative is typically your reference point, and some folks bond that to chassis/PE at a single point to avoid ground loops. Victron's own wiring unlimited guide covers this really well — free PDF, well worth a read if you haven't already.

What battery chemistry are you running? That can sometimes influence how people approach the bonding question in practice.

@JennyCole one thing worth flagging that nobody's mentioned yet — your negative busbar bonding matters here too. In a typical 12/24/48V caravan setup the DC negative should be bonded to PE at one single point only, usually at the inverter/charger chassis. Do it in multiple places and you're asking for ground loops.

Victron's own wiring unlimited doc is pretty clear on this. Worth a read before you touch anything.

Also — is your static on a proper site hookup or running island mode? Changes things slightly in terms of how the MultiPlus manages the neutral-earth bond on the AC output.

Good points from @JYT_Solar, @DerekKnight and @RelayDream already covering the essentials.

One thing I'd add from my own van and static installs — the Lynx Power In chassis itself has those small earthing lugs on the enclosure for a reason. Bonding the enclosure to your chassis earth (or PE rail in a static setup) is worth doing even though the DC busbars obviously aren't PE-connected. It's about fault containment — if something catastrophic happens inside, you want the metalwork at a safe potential rather than floating.

In my MultiPlus-II setup I run a short 6mm² green/yellow from the Lynx enclosure lug to my main earth bar. Victron's own documentation is a bit quiet on this but it's consistent with general BS 7671 practice for exposed conductive parts of equipment.

Small detail, but worth the five minutes.

Thread title's in French but the question's universal — DC negative to PE only at one point (usually the MultiPlus chassis), not at the Lynx Power In itself, unless you fancy chasing gremlins through your BMS readings at 2am like I did on the narrowboat. 🚤 @RelayDream's spot on about the negative bonding but worth adding: the Lynx Power In is purely a DC distribution point, Victron never intended it as a PE bonding location — your earth star point lives elsewhere. Check the Victron wiring unlimited guide, page on DC systems, it's quite explicit about this.