Nieuwe installatie Victron multiplus 6k5 aardlekprobleem?

Had the exact same heart-stopping moment with my Victron Multiplus-II when I first wired up the shepherd's hut — everything hummed beautifully for about 45 seconds before the RCD tripped like it had somewhere better to be.

Turned out the classic culprit: neutral-earth bonding. The Multiplus creates its own N-E bond when islanded, so if your incoming supply also has one, you've essentially got two bonding points and the RCD loses the plot entirely.

A few things worth checking:

• Disable the internal N-E relay in VEConfigure if you're running ESS and staying grid-tied — let the grid handle bonding
• If you're fully off-grid (like me, no DNO connection whatsoever), make sure the bond exists only at the inverter
• Double-check your Pylontech comms cable — a dodgy CAN bus connection can cause the system to behave erratically during that initial handshake period, which looks like an earth fault but isn't

The Victron ESS assistant settings in VEConfigure are also worth revisiting — specifically the "AC input 1 ignore" setting if your grid meter isn't being read correctly.

Anyone else running a Pylontech + Multiplus ESS setup in the UK had grief with their consumer unit's RCD type? I've seen Type AC RCDs go absolutely haywire with inverter-generated waveforms — a Type B or at minimum Type A is really what you want downstream of any quality inverter.

What RCD/RCBO setup are you running? Might help narrow it down. 🔌

@RiverSpirit classic symptom of N-E bonding conflict.

The Multiplus-II creates its own neutral-earth bond internally when running in island mode. If your RCD sees a second bond — typically from a PME/TN-C-S supply connection or a generator with its own bond — you get phantom earth leakage current that trips the RCD immediately or within seconds.

Key checks:

• Transfer switch position — is the unit correctly switching between shore/grid and inverter?
• Grid input neutral — is it bonded anywhere downstream of the Multiplus?
• RCD type — standard Type AC RCDs can nuisance-trip on the quasi-sine characteristics; fit a Type A minimum, ideally Type F if you have any variable-speed loads

On my narrowboat I had to remove the marina shore-power earth bond entirely and let Victron handle it. Problem solved immediately.

What's your supply source — grid, generator, or pure solar?

@RiverSpirit had the exact same faff on my narrowboat — turned out I had two N-E bonds fighting each other like a pair of drunk swans, one inside the Multiplus and one some muppet (me) had wired into the consumer unit.

@ThistleVicky is right about the double-bond issue — to add some practical detail: check your shore power inlet or any transfer switch for a hardwired N-E link. On a narrowboat that's often hiding in the shoreline socket housing or an older CU.

On the Multiplus-II specifically, the internal bond is controlled by the Ground Relay setting in VEConfigure. If you're in a standalone off-grid setup with no shore power ever connected, you want that enabled and every other bond removed. If you're occasionally connecting shore power, the relay handles switching automatically — but only if wired correctly per the Victron installation manual section 3.4.

Done this twice now — once on the hut, once retrofitting a boat. Both times the stray bond was somewhere embarrassingly obvious once I actually traced the neutral conductor properly.

Great thread to land on as a newcomer! @LH_Marine and @ThistleVicky have nailed the diagnosis tbh.

One thing worth adding — Victron's VE.Configure tool lets you toggle the N-E bond setting directly in the Multiplus-II firmware. Took me about 10 mins on my motorhome install once I realised that was the culprit. Dead simple when you know where to look.

Also worth grabbing a Victron cerbo or even just a cheap MK3-USB interface so you can poke around the settings without guessing.

Don't be put off by this teething stuff — once it's sorted these units are rock solid 🙌

Good points from @LH_Marine and @ThistleVicky on the double-bond issue — that's almost certainly it.

One thing worth checking specifically on the Multiplus-II: in VE.Configure there's a ground relay setting that controls whether the unit creates its own N-E bond when running in inverter mode. If your installation already has a bond elsewhere (shore power inlet, generator, or a separate earth bar), you'll want that relay disabled.

For my static caravan setup I had to work through this methodically — disconnected everything, confirmed exactly one N-E bond point, then re-enabled the ground relay in VE.Configure only after I was certain.

Worth also checking:

• RCD type — Multiplus-II can produce DC residual current, so you ideally need a Type B RCD upstream, not just Type A
• Whether your incoming supply is TN-S or TN-C-S, as that affects where your bond should live

What does your earthing arrangement look like at the supply end?