XW pro optional ground?

[zanydroid]

What about the new 3 wire feeder you put in last year? Can you retrofit or replace that?

TBH that should have been done to modern code (4 wire, since it was way past the code change), then you would have had more options to address this…

You might also consider various isolation transformers and aggressive use of GFCI breakers to mitigate the risk.

This grounding scheme is getting farther away from what I think is advisable to figure out on your own as a non grounding expert / trying to crowdsource an answer.

 

[Lake country]

What about the new 3 wire feeder you put in last year? Can you retrofit or replace that?

TBH that should have been done to modern code (4 wire, since it was way past the code change), then you would have had more options to address this…

You might also consider various isolation transformers and aggressive use of GFCI breakers to mitigate the risk.

This grounding scheme is getting farther away from what I think is advisable to figure out on your own as a non grounding expert / trying to crowdsource an answer.

Adding a ground from the clp to the xw could be doable next year. I'd like to avoid it though. At the end of the day this is about not getting shocked. As far as I can tell as long as appliances branched from the CLP have a ground that is bonded to neutral at the source of power or the clp itself the breaker will trip if a fault occurs. Yes it's not up to the current code but the actual safety factor will work as intended.

 

[hwy17]

I'm not sure if a 4 wire just from XW to CLP would improve the options a lot here.

 

[zanydroid]

Adding a ground from the clp to the xw could be doable next year. I'd like to avoid it though. At the end of the day this is about not getting shocked. As far as I can tell as long as appliances branched from the CLP have a ground that is bonded to neutral at the source of power or the clp itself the breaker will trip if a fault occurs.

That is true for line to chassis fault. But in your system the chance of a lost neutral fault also causing your ground to raise to line level has increased substantially.

Yes it's not up to the current code but the actual safety factor will work as intended.

I don’t think the full fault analysis has been done. I would be more comfortable if a GFCI was monkey patched in since that guards against some kinds of lost ground faults.

BUT the 120/240 GFCI breakers likely need neutral to function so even that is dicy if the original sin is a lost neutral.

I'm not sure if a 4 wire just from XW to CLP would improve the options a lot here.

I was thinking it could be used to split the N-G bond at the outbuilding. It’s not to code but there are exceptions for running EGC on unrelated path (NOT for feeders)

 

[zanydroid]

I'm not sure if a 4 wire just from XW to CLP would improve the options a lot here.

Another idea: how about reassign neutral in the mobile feeder to ground (so feeder is 240v only) and add an isolation transformer with split secondary on the other end to form neutral. Or form neutral with an appropriate AIO (needs to be fully isolated topology so it counts as separately derived).

For #4 aluminum the ampacity is I believe 60A or so, so a ~14KVA transformer would be needed.