Will I regret this temp grounding setup?

[solarenvy]

Today in “I should know better”, I’m running through some tests in a [remote] cabin setup. I’ve been on here learning long enough to have a lot of confidence in the end-state. But I may have some less-than-ideal temporary scenarios as I get things ready to be configured for the long-term.

For reference, this is close to the end-state (plus all the appropriate ground runs, etc.)



Currently I only have the “XP Sub” wired up locally in the PV shed (which is attached to the side of the cabin). Inverter is feeding this panel and some local outlets for testing. I have a 6AWG bare copper wire running to the “House Main” for grounding, which is grid service entry currently (“Grid Main” is not in place yet) and is N/G bonded.

As-is, the “XP Sub” is NOT N/G bonded and has dedicated neutral and ground bars for termination.

The question(s):

- Is it kosher to ground the XP Sub panel (temporarily) this way?
- should the XP Sub be bonded locally since it’s technically not configured as a sub panel yet?
- if ^yes^ can it be bonded while still grounding via the main panel?
- what else should i know?

My backup plan was to install a grounding rod next to the shed, ground the panel there, and bond N/G locally…but ran out of time. I will repeat that this is a TEMPORARY setup while I get all my things in order.

Don’t yell at me. Thanks in advance!

 

[robbob2112]

Looks like your drawing is for a manual transfer switch so ALL loads will be running from grid OR all loads will be running from the XP.

So you are essential running off-grid and only pulling power from the grid to charge batteries if you need to.

So, zero chance of backfeed - no PoCo unhappyness

make sure to turn off the N-G bond in the inverter - you will have a N-G bond in the main panel no matter if you are on-grid or off-grid

Use just the main ground rod for the service entrance - it should come in and be tied to the ground bar in the main panel and that will in turn tied to all the other equipment ground bars and cases.

Make sure to refer to the EGC chart and get the size correct for the inverter panel ground wire - you can find it on page 2 or 3 of my answer thread (first link in my signature)

 

[solarenvy]

Thanks robbob2112, appreciate the feedback.

Any thoughts on the “temporary state” configuration? TL;DR: running only the ground from PV panel to main panel for temporary grounding. Main panel is N/G bonded, PV panel is not bonded. Also note that PV panel is currently not wired into main panel (besides EGC).

That’s really my main concern at the moment.

 

[robbob2112]

PV panel not bonded - GOOD - that is only in mobile applications - (bonded in panels means PV negative is connected to the EGC)

N-G bond only in main panel - There can be only one - GOOD

If by PV panel you meant PV inverter - the terms you used is confusion causing.

 

[solarenvy]

Apologies, my wording may have been confusing. By “PV Panel”, I’m referring to the load center (sub panel) adjacent to the inverter.

I’m totally onboard with N-G bond only in main panel and that has been in my design all along. The question was about the “PV Panel” (PV sub panel) in this temporary setup — since it currently is NOT wired into a breaker at the main panel is it technically considered a sub panel?

Which raises the question — what, technically, makes a sub panel a sub panel?
a) L1/L2/N/G wired into a main?
b) N/G wired into a main?
c) G wired into a main?
d) none of the above?

 

[robbob2112]

a - L1, L2, N, G wired to the main panel.

What you have is a second independant power source that used the N and G from the main - with a manual transfer switch only L1 and L2 are getting switched while N and G are staying connected all the time.

Think of it like hooking an unbonded generator up to the house.