Ready to "flip the switch" but confused about grounding. 2x 5000w inverters in parallel for 240 in my off grid rv.

Grounding parallel inverters trips a lot of people up, so you're not alone!

Key thing with two inverters running in parallel for split-phase (or stacked for 240V) — you only want one neutral-ground bond. Most inverters have a built-in N-G bond that's fine when solo, but run two together and you've suddenly got two bond points, which causes all sorts of grief with RCDs tripping and potential circulating currents.

What inverters are you running? If they're Victron Multis or Quattros, the parallel setup is well documented and they handle the bonding properly through the master unit. Other brands can be trickier.

Practical steps I'd suggest:

• Disable the N-G bond on the slave inverter if your units allow it
• Run a single solid earth from your chassis to the system earth bar
• Keep DC negative and AC earth/neutral as separate paths — don't let them touch except at one defined point

I did something similar on my static when I stacked two units for higher loads. Took a bit of head-scratching but once the bonding was sorted everything played nicely and the RCD stopped being paranoid.

Worth grabbing a copy of the BS 7671 wiring regs if you haven't — the off-grid sections are actually quite useful for understanding how earthing schemes apply to standalone systems.

What's your battery bank and earthing arrangement looking like so far? That'll help work out the best approach. Others on here have done parallel setups too — hopefully they'll chime in. 🙂

Hey @BirchLover, great point about the single neutral-ground bond!

Just to add for the OP — make sure that bond is happening at your main distribution panel, not inside either inverter itself. Most inverters have an internal N-G bond that's meant for standalone use, and leaving both active when paralleling causes all sorts of grief with RCD/RCBO trips and potential safety issues.

Worth checking your inverter manual specifically — some models like Victron MultiPlus have a dedicated ground relay that you can disable via VE.Configure when paralleling, precisely for this reason.

Also don't forget your DC chassis ground is a separate consideration entirely from your AC neutral-ground bond. Both matter, but they're doing different jobs.

What inverters are you running? That'd help narrow down the specifics for your setup. 🙂

Really good thread to raise before flipping that switch — much better to sort grounding before energising the system!

One practical addition: with parallel inverters, confirm in your inverter documentation which unit is designated master — on most setups (Victron Multiplus stacked configs, for example) the master handles the neutral-ground bond logic. The slave unit should have its bond disabled or left to factory default depending on the model.

Also worth picking up a clamp meter to verify there's no stray current on your ground conductor once everything's live. Caught a double-bonding issue on my narrowboat that way — silent problem until it wasn't.

Check your inverter manufacturer's parallel wiring guide specifically; generic advice only goes so far when models differ.

Good points raised already, but worth flagging something specific to the parallel configuration: when you slave two inverters together, check your manufacturer's documentation carefully about which unit handles the neutral-ground bond. On Victron Multis running in parallel via VE.Bus, the bond is managed internally and you absolutely do not want an additional external bond — doing so creates a ground loop that'll confuse your RCD/RCBO and potentially cause nuisance tripping or worse.

Also, if you're in a vehicle or static caravan context, your chassis/frame earth needs tying into this properly. A lot of people connect DC negative to chassis but forget to integrate the AC earth correctly, leaving them with a floating AC ground relative to the metalwork they're touching every day.

What inverter brand are you running? That'll determine exactly where the bond lives and whether it's switchable.

Slightly tangential but relevant — does the OP know which specific inverters they're running? The grounding behaviour can differ quite a bit between models. On my van build I'm using a Victron Multiplus, and Victron's documentation is very explicit about where the N-PE bond should (and shouldn't) sit depending on whether you're in inverter mode vs. shore power mode — the internal transfer switch actually handles some of this automatically.

If the OP is using a different brand (Renogy, Growatt, etc.), I'd want to know whether those units have an internal N-PE bond that's always present or only active in certain modes, because stacking two units with permanent internal bonds could create a double-bond situation that @BirchLover and @SaltySocket are rightly cautioning against.

What exact inverter model are we talking about here?