Off-grid Giandel inverter with 2 AC outputs wired into 2 separate RCBOs - weird or normal RCD behaviour?

[GeeGee]

Ok, so this thread is an extension to my original 12V 3300W off-grid build here.

I started a new thread for focus.

What I've basically done is add additional RCD protection to the system by adding RCBO breakers to both AC outputs of the inverter.

Things you should know for context:
- Inverter has no N-G bond
- Inverter has no RCD protection
- Inverter 2 AC outputs / receptacles
- each AC output is running into separate RCBOs via the consumer/sub panel (see images & schema)
- N-G bond made in the consumer panel

My assumption
- If a get a ground fault on one of the AC outputs, then only the RCBO for that output should trip

Here's what is actually happening:
- If I simulate a ground fault on AC output 1 (I do this using the Low Impedance (LoZ) feature on my Digital Multimeter (DMM) by touching the DMM prongs on the RCBO), then both RCBOs trips
- Same behaviour goes for AC Output 2, i.e. if I simulate a ground fault then both RCBOs trip

Here's my questions:
- Can someone please explain what is going on here? I don't understand why a ground fault on one of the AC outputs is causing both RCBOs to trip. It's as if both AC outputs are on the same circuit?
- Are both RCBOs tripping because of the way the inverter is internally wired OR because I added a N-G bond? Can I do additional tests to confirm which?
- Am I causing any safety issues with my wiring?


Kinds Regards
GeeGee


Basic Schema

 

[timselectric]

Your N/G bond is on the wrong side of the RCBOs.
It should be on the line side (input).

 

[GeeGee]

Your N/G bond is on the wrong side of the RCBOs.
It should be on the line side (input).

Something like this?

 

[timselectric]

Something like this?


View attachment 258704

Yes

 

[GeeGee]

ok, tx and tx for the quick reply......its appreciated

I will re-wire tomorrow and test again and post back my results....fingers crossed.

GeeGee

 

[robbob2112]

I didn't think australia had N-G bond because it had no Neutral - all 230vac or 3-phase?

 

[GeeGee]

@timselectric - IT WORKED! Bloody thing worked as expected......happy days. Thanks heaps.

 

[timselectric]

@timselectric - IT WORKED! Bloody thing worked as expected......happy days. Thanks heaps.

Great news.

 

[robbob2112]

I see, all 3 phase - residential uses a phase and neutral... and neutral/ground bond... it just isn't split phase like we use