Giandel open ground again!

[sunnysea]

I am re-opening the pandora box on open ground Giandel inverters

I have a 24v 3,000 watt Giandel pure sine wave inverter which is performing great. It is installed in a small shed setting where I have access to a real dedicated earth ground.

This specific inverter only has a ground lug connected to the chassis (and to both the ground prong of the outlets and the ground block terminal) but does not do a neutral/ground bound at all.

I have a DC negative/ground bound in the system. I have the chassis of the inverter connected to my earth ground too but end up in an "open ground" scenario if I use a regular outlet tester.

Since I am not in a mobile scenario (RV/boat), I figured I would connect the inverter's terminal block to a small panel, do a neutral/ground bond there and run a few outlets from there (GFCI protected). This should give me better protected outlets and more peace of mind (or is it?).

I found lots of discussions on the topic in this forum and different suggestions coming from the manufacturer. Here is a past suggestion and here is the one I just received from them which is slightly different:



(notice how they do the bound before the GFCI instead of after compared to the previous suggestion)

This looks good to me and close to what I was shooting for: do the neutral bound in the panel, have a regular 20 amp breaker there and put a string of outlets with the first one using a GFCI 20 amp receptacle.

I am trying to understand the concerns from the manufacturer and why they don't recommend this setup.

--- all hypothesis from me starting here, wondering if any of here is right ---

The manufacturer says this wiring carries shock risk (I imagine in fault scenarios). Given the inverter's ground lug is already connected to the chassis, I assume by doing a N/G bound, I am making things worse in the case of a fault. Maybe a loop (in the inverter) that, in case of a fault in the inverter would energized the chassis until the inverter dies?

If I wire the GFCI like they recommended in the past, it sounds like I am protecting humans touching the chassis when it is energized in a fault (touching the chassis would trip the GFCI). But I think the inverter may die in both scenarios.

When a true earth ground is available, I have a feeling not doing a N/G bound is about protecting the inverter versus protecting the outlets connected to the inverter (and humans interacting with the appliances on them). While the inverter is probably more expensive than anything I will connect to its outlets, I'd rather protect "human life" rather than the inverter. This exact thinking makes me realize that maybe I should just use a GFCI receptacle downstream of the inverter without doing a N/G bound? GFCI does not need a N/G bound to function and in old houses where no grounding is available, I believe this is what the NEC recommend. This could give me the best of the two worlds: protect the inverter in case of a fault, the appliances connected to it, and the humans part of the circuit in a fault?

 

[12VoltInstalls]

Did you solve this out?
Unfortunate you didn’t receive a response initially but you can find this topic in another current thread

 

[meetyg]

I am re-opening the pandora box on open ground Giandel inverters

I have a 24v 3,000 watt Giandel pure sine wave inverter which is performing great. It is installed in a small shed setting where I have access to a real dedicated earth ground.

This specific inverter only has a ground lug connected to the chassis (and to both the ground prong of the outlets and the ground block terminal) but does not do a neutral/ground bound at all.

I have a DC negative/ground bound in the system. I have the chassis of the inverter connected to my earth ground too but end up in an "open ground" scenario if I use a regular outlet tester.

Since I am not in a mobile scenario (RV/boat), I figured I would connect the inverter's terminal block to a small panel, do a neutral/ground bond there and run a few outlets from there (GFCI protected). This should give me better protected outlets and more peace of mind (or is it?).

I found lots of discussions on the topic in this forum and different suggestions coming from the manufacturer. Here is a past suggestion and here is the one I just received from them which is slightly different:

View attachment 113910

(notice how they do the bound before the GFCI instead of after compared to the previous suggestion)

This looks good to me and close to what I was shooting for: do the neutral bound in the panel, have a regular 20 amp breaker there and put a string of outlets with the first one using a GFCI 20 amp receptacle.

I am trying to understand the concerns from the manufacturer and why they don't recommend this setup.

--- all hypothesis from me starting here, wondering if any of here is right ---

The manufacturer says this wiring carries shock risk (I imagine in fault scenarios). Given the inverter's ground lug is already connected to the chassis, I assume by doing a N/G bound, I am making things worse in the case of a fault. Maybe a loop (in the inverter) that, in case of a fault in the inverter would energized the chassis until the inverter dies?

If I wire the GFCI like they recommended in the past, it sounds like I am protecting humans touching the chassis when it is energized in a fault (touching the chassis would trip the GFCI). But I think the inverter may die in both scenarios.

When a true earth ground is available, I have a feeling not doing a N/G bound is about protecting the inverter versus protecting the outlets connected to the inverter (and humans interacting with the appliances on them). While the inverter is probably more expensive than anything I will connect to its outlets, I'd rather protect "human life" rather than the inverter. This exact thinking makes me realize that maybe I should just use a GFCI receptacle downstream of the inverter without doing a N/G bound? GFCI does not need a N/G bound to function and in old houses where no grounding is available, I believe this is what the NEC recommend. This could give me the best of the two worlds: protect the inverter in case of a fault, the appliances connected to it, and the humans part of the circuit in a fault?

Something doesn't look right in that diagram:
If I'm not mistaken, it shows two N-G bonds: One before the GFCI and another after it, in the panel.
This setup would probably cause the GFCI to trip immediately.
I would have the N-G bond in a single place, before, the GFCI, but also connect inverter ground to panel ground, without any additional N-G bonds in the panel.