fault current vs ground reference

[John Frum]

The inverter in my system has provision for equipment ground.
I plan to "pigtail" the equipment ground to the negative current carrying conductor.
The pigtail and negative current carrying conductor are more than large enough gauge to handle fault current back to the battery and trip the OCP.
The wire to premises ground is not big enough to handle fault current.
I think that its "OK" because the path to premises ground's job in this case is reference to earth.
Let me know if I missed the mark.

 

[Zil]

I'm in an RV and take my case ground to the chassis that is tied to the battery negative. I have had no problem in 3 years. I am only using 12 volt system. I have no regular mains supply coming in. I would have to think through any grid tied system that may need some reference to earth.

 

[John Frum]

I'm in an RV and take my case ground to the chassis that is tied to the battery negative. I have had no problem in 3 years. I am only using 12 volt system. I have no regular mains supply coming in. I would have to think through any grid tied system that may need some reference to earth.

I can't tell if you answered my question or not.
Is it ok that the "dirt circuit" wire is not able to handle as much current as fault clearance wire?

 

[Zil]

If you refer to the case grounding lug. That goes to battery negative chassis in RV. In home it goes to the green or bare earth ground. Not the white 'common' wire.

 

[John Frum]

If you refer to the case grounding lug. That goes to battery negative chassis in RV. In home it goes to the green or bare earth ground. Not the white 'common' wire.

No idea what that has to do with the price of elephant rated snowmobiles.

 

[Zil]

It is just Simpson math. Snowmobiles powered by elephants are so common but not in demand.

 

[Mex Rider]

The inverter in my system has provision for equipment ground.
I plan to "pigtail" the equipment ground to the negative current carrying conductor.
The pigtail and negative current carrying conductor are more than large enough gauge to handle fault current back to the battery and trip the OCP.
The wire to premises ground is not big enough to handle fault current.
I think that its "OK" because the path to premises ground's job in this case is reference to earth.
Let me know if I missed the mark.

This probably won't answer your question either but...Victron's installation manual for the multiplus inverter charger says the ground cable needs to be large enough to handle the total possible fault current. Not referring to equipment chassis ground... sorry can' t help with the elephants.

 

[Zil]

Wow. Someone kicked over the elephant. There is no negative battery return to earth. Any battery power will only be battery terminal to battery terminal "fault current". The ac has a true ground reference in the earth so only the ac "fault current" will be into the earth. The battery could get involved if, say, the grid powered battery charger has a fault and feeds ac current into the battery positive, through the battery negative, into the combined dc-negative/ac-earth ground. But that only kills off the battery. We can still ride the snowmobile.