question

Others have told me that I should also NOT connect the ground cable from the Honda to the Quattro since the Honda is producing split phase power?

Hi from Colorado, @AlaskanNoob .

The Quattro that you have seems to be one of the international models, not intended for the American market. By changing the frequency from 50 hz to 60 hz, the unit could invert for 240vAC American loads such as a water pump which requires only 240v to run. Taking a clothes dryer as an example, however, some of those appliances need 240 to drive the heating element but they also need 120vAC to run the tumbling & the blower...and you won't get both of those voltages from a single Quattro, whether it's a US version or an international version.

There's a grounding problem as you've already noticed, b/c the N side would typically be "earthed" or grounded if installed in England, etc...yet would need to be floating in order to run a 240v American water pump properly. Also, a 240v American appliance is designed for both legs to be overcurrent protected (double pole breaker) but only ungrounded conductors can be broken b/c the path for lightning to earth must never be interrupted. This is why the white Neutral wires are never switched or fused. These are code violations & possibly safety concerns but let's set that aside for now b/c the safety minutia is above my pay grade.

Assuming that your loads need 120v and 240v power "just like downtown", the best way would be with two (smaller) American style Quattros with the AC stacked in series & that gets you a total of three power wires in the architecture: two hots & a neutral with the two hots 180 degrees out of phase to each other. That would match the architecture for your Honda generator & the whole system end to end would be just like downtown. Also you then would ground the neutral at one point in the overall system for US code compliance & good installation practice.

If instead you have only 240v loads (& if you can't back out of the purchase decision already made), it would be correct to not connect the neutral from the Honda. The problem then is you have an ungrounded system even if you ground the neutral at the generator, since the neutral stops there.

Victron sells an "autoformer" & Outback sells a bigger one. This is a special transformer which can induce a neutral so you wind up with three wires again on the output side of the xformer. Then your system is still ungrounded for the distance between the Quattro and the input side of the autoformer.

There are various ways to wire up an autoformer & it takes some noodling to figure it out. That's because there's more than one way to use an autoformer in an off grid power system.

I trust this will be helpful. Stay safe & "Sunny Days".

see https://community.victronenergy.com/questions/67334/multiplus-230vac-input-from-240v-split-phase-gener.html

Hi again, @AlaskanNoob ~ Here are American vocabulary terms on the topic of grounding. YouTube might have some good explanations: "equipment ground" "grounding electrode" "GEC" aka "grounding electrode conductor" "neutral to ground bond" aka "N-G bond". Getting a handle on these terms might prove helpful.

The other Community thread to which @rickc linked you is all good information. Assuming that you proceed with installing the Euro style Quattro, the comment about disabling the internal N-G bonding relay is very important, because if you've connected a generator hot to the N bolt & the relay is still switched to ground when the actual power shows up on the N bolt, that's likely to be a dead short with some drama.

This is the problem when a wire connected to the neutral bolt is not really neutral relative to the earth. That's part of why I think your vendor should have sold you different hardware.

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Victron P/N QUA483100100 & P/N QUA485021100 are Quattros intended for the US market (although neither are UL listed & therefore wouldn't pass code in most US jurisdictions). Buying two identical Quattros would result in a system that's 120/240 60 hz end to end with no need for autoformers (unless the 120v loads were seriously unbalanced). If you stack two of the 5kW Quattros, they work together like one 10kW inverter/charger with 120/240 architecture.

Buying twin Quattros prolly costs more per rated kilowatt and it does complicate the DC side of your system, but the AC side is simplified & all the grounding & bonding decisions match the baked in knowledge of normal US electricians. If the property changes hands or folks need to look inside the blue boxes years into the future, the AC wires you have bolted to the Neutral studs will be actual neutrals if you install twin Quattros.

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With a multimeter set to "beep" for continuity, you can check to see if the Honda genset has the AC neutral factory bonded to the metal frame. This would be good for you to know before getting into the grounding/bonding discussion with your electrician. The genny should not have anything plugged into its power outlets & should not be running. Place one meter probe onto the metal lug on the frame & poke the other probe into the Neutral slot on the turn lock receptacle. If you hear a beep that means it's internally bonded.

If so, you & the electrician may decide to see if the genset can be hacked to isolate N from G, or (provided that the turn-lock plug is never disconnected) you may decide to rely on the generator to provide the single point in the AC wiring where the neutral and the ground are bonded. "Single point bonding" between N & G is required by the NEC for good scientific reasons. I assume that your work won't be code inspected, but many provisions of the NEC are forged in the fire & beneficial.

Sunny days...