Passenger side busbar grounding question

donmontalvo · May 2025

2024 T@B 320S Boondock Black Canyon.

I installed an EMS and will be testing over the weekend.

Today I read on the tab-rv forum that the two Philips screws that attach the passenger side wheel-well busbar attach to an aluminum frame, which in turn attaches to the steel frame.

If that's true, I may have undone the grounding...hopefully one of the wires on the busbar goes to the chassis.

Is there a way to confirm this? I have a multimeter, should I connect the BLACK wire to the bare copper chassis ground on the WFCO, and the RED wire to the busbar?

If my suspicion is right, it should show 0 or close to it.

Thoughts?

TIA,
Don

Image: https://us.v-cdn.net/5021717/uploads/editor/by/jyfjbwctz4er.jpeg

MuttonChops · May 2025

Overall I agree with your verification approach. However, am not sure what to do about the battery negative terminal somehow creating a path back to the Power Center; perhaps disconnect that terminal and turn Cut-Off switch off as well.

Do note not all 320S rigs have the buss bar to chassis screw connection as some owners have reported a Chassis Ground connection at the 7-pin junction box.

On my year-2018 there is the buss bar to chassis screw. Also on my rig I found the 120VAC Copper Wire Ground to chassis Broken at the frame/chassis screw terminal which is on the belly pan side of the frame.

This Reference Diagram is not 320S specific.

Image: https://us.v-cdn.net/5021717/uploads/editor/g8/dqsjdqnbr7gw.jpg

donmontalvo · May 2025

I confirmed with nuCamp support that busbar "runs to the 7-pin junction box, which then connects to the chassis grounding lug near the tongue". The post I saw was incorrect, moving the busbar didn't affect its chassis ground.

MuttonChops · May 2025

donmontalvo said:
. . . confirmed with nuCamp support that busbar "runs to the 7-pin junction box, which then connects to the chassis grounding lug near the tongue".

Thanks for update.
That said . . . it you have the time/energy consider verifying nüCamp's information for your specific rig.

For my yr-2018 there was no junction box (7-pin) connection to chassis ground.
That was validated when I shorted the battery positive terminal to chassis (wrench slipped) and completely burned-out the ground wire from the junction box to ground buss bar - - which was the chassis ground point.

donmontalvo · May 2025

MuttonChops said:

donmontalvo said:
. . . confirmed with nuCamp support that busbar "runs to the 7-pin junction box, which then connects to the chassis grounding lug near the tongue".

...it you have the time/energy consider verifying nüCamp's information for your specific rig...

No need, everything is working on my 2024 320S. The busbar is still grounded. Just a bit confused by the posts I found.

On a side note, when I added a chassis ground for my new inverter, I ran a new one on the passenger side.

So all is good.

Image: https://us.v-cdn.net/5021717/uploads/editor/m6/qduj4riqbvrm.png

ScottG · May 2025

donmontalvo said:

I confirmed with nuCamp support that busbar "runs to the 7-pin junction box, which then connects to the chassis grounding lug near the tongue". The post I saw was incorrect, moving the busbar didn't affect its chassis ground.

The post you saw (likely mine) was not "incorrect." nuCamp added the chassis ground connection at the 7-pin junction box sometime after 2015. My 2015 does not have this connection--the only DC chassis ground is via the busbar mounting screws that extend into the aluminum floor framing.

I'm not being argumentative or defensive, but rather emphasizing that there is a lot of variation in how T@Bs have been configured through the years. In earlier models, changes were often made partway through a production year. Owners are advised to know their own trailer and not necessarily believe that what you read here applies universally.

The DC grounding issue first surfaced as a possible contributor to Alde corrosion problems. However, this was likely a red herring. I've long had it on my list to add a chassis ground at the junction box, but since--in my case anyway--it seems to make no functional difference, I've yet to get around to it.

donmontalvo · May 2025

ScottG said:

donmontalvo said:

I confirmed with nuCamp support that busbar "runs to the 7-pin junction box, which then connects to the chassis grounding lug near the tongue". The post I saw was incorrect, moving the busbar didn't affect its chassis ground.

The post you saw (likely mine) was not "incorrect." nuCamp added the chassis ground connection at the 7-pin junction box sometime after 2015. My 2015 does not have this connection--the only DC chassis ground is via the busbar mounting screws that extend into the aluminum floor framing.
I'm not being argumentative or defensive, but rather emphasizing that there is a lot of variation in how T@Bs have been configured through the years. In earlier models, changes were often made partway through a production year. Owners are advised to know their own trailer and not necessarily believe that what you read here applies universally.
The DC grounding issue first surfaced as a possible contributor to Alde corrosion problems. However, this was likely a red herring. I've long had it on my list to add a chassis ground at the junction box, but since--in my case anyway--it seems to make no functional difference, I've yet to get around to it.

Understood, what I meant is that for my case the post I saw was not correct. Forum can be messy, not always possible to tag posts so readers don't have to guess. TBH, surprised nuCamp didn't run a wire from the busbar on your 2015 to the chassis directly. I'm guessing not all electronics decisions were fully vetted in the past (and/or even today), hence why digging is so important.

Speaking of grounding busbars, when I reattached the passenger side shelf in my 2024 320S, I noticed there is another chassis ground busbar. I should have taken the time to trace the chassis ground, to have a good understanding of how the wiring is set up. My goal is to have a complete schematic over time. If I did trace it, I still would have run my own chassis ground (green in my schematic). I didn't want to run the risk of affecting anything else in my solar/battery/inverter upgrade.

That said, I plan to circle back to that shelf to reinstall the switch that blue up when the shelf fell off the wall. At the time it was more important to get the shelf back up, rather than wait for a replacement switch to come in (which could take weeks), and I have to pay for it since it got fubar'd when I was repairing the shelf.

Thanks four posts, sorry I didn't word thing better, didn't mean to imply your post was wrong, just wasn't right for my scenario.

donmontalvo · May 2025

I forgot to mention, if you decide to run your own ground, it doesn't necessarily need to be by the junction box. The shop that ran my new ground had the solid copper "wire" but recommended going with stranded tinned copper, to avoid any damage or looseness from vibrations. Here are a couple pics sent to me by the shop. To give you an idea of their qualifications, all their techs are certified by Victron and some other companies, and are the premiere authorized Victron shop in Quartzsite, AZ. When I retired in Oct and bought my 320, I went there for a few months. During that time I learned a lot about how to scale up LiFePO4/solar/inverter systems.

Passenger side busbar grounding question

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