Does chassis ground provide protection?

[Bluedog225]

I’ve got my Victron system in a conex box. It is not in its final resting place yet.

Once it is moved, I will drive the ground rod(s).

Is there any benefit from a safety perspective of “grounding” to the conex? Maybe I should say “bonding” to the conex. Or does that simply provide a common reference point?

Seems like the conex is the same as a recreational vehicle. I can see having everything in the conex at the same potential being a benefit. But it would offer no protection against getting shocked when standing on the actual ground.

Am I in the right ballpark?

Thanks

 

[timselectric]

Everything conductive should be bonded to your grounding system.
Everything that you can touch, needs to be safe to do so.

 

[Bluedog225]

100% understood. But I’m not sure how that applies to an ungrounded system like a recreational vehicle. Does the chassis (or other big chunk of metal) provide protection? I’m confused since nothing goes to earth.

 

[timselectric]

I'm sure that your Victron system is a grounded system.
Earth has nothing to do with electrical grounding. Other than the Earth also needs to be connected to the grounding system to make it (the Earth) safe.

 

[Will Prowse]

It is recommended to have a reference potential of 0 Volts. Technically a chassis is not a true earth potential though..

So ambulances and buses have a small grounding strap to dissapate excess charge accumulation from chassis. It happens.

Really depends on why you need to ground your system though. For my mobile systems, I don't see much benefit and run them floating.

Some circuits are sensitive though and may require some form of electron sink. Such as radio communication. Look at the earth grounding required for cell phone towers. Also if you have a large solar array, charge can accumulate and negatively affect output. But this only happens on extremely large systems. I also think if you're carrying certain types of fuel, like cryogenic frozen rocket propellants, you need proper earth grounding.

So really depends on what you're doing.

 

[Hedges]

RVs should work fine with no electrical connections to earth. If you touch them and make one connection, there is no other path for current to flow.

Shore power should provide ground reference for RV chassis. And neutral/ground bonding.

If two people touch chassis while standing on earth, both same potential so no current flows. (if "objectionable current" flows through chassis, or the earth has "step potential" due to a downed power line or lightning, then you two would be completing a circuit and would get current flow.

Any outlets used outdoors ought to be GFCI.

PV panels deployed elsewhere have been a problem, because PV+/- carry AC from many inverters. "ground" wire from RV & inverter chassis to PV frames should take care of that.

yeah, we do get static build up when driving. Can be a problem when you touch gas nozzle to open fill neck.
We've heard of cell phones igniting vapors, doubt that is the actual cause, rather energetic young people jumping in and out of the seat while filling.

 

[Will Prowse]

I’ve got my Victron system in a conex box. It is not in its final resting place yet.

Once it is moved, I will drive the ground rod(s).

Is there any benefit from a safety perspective of “grounding” to the conex? Maybe I should say “bonding” to the conex. Or does that simply provide a common reference point?

Seems like the conex is the same as a recreational vehicle. I can see having everything in the conex at the same potential being a benefit. But it would offer no protection against getting shocked when standing on the actual ground.

Am I in the right ballpark?

Thanks

If you do connect to shore power, having a solid ground connection is very important though. A good reference for doing this properly is a marine electrical wiring manuals. To summarize, make sure proper size conductor is used and ensure connections are perfect.

 

[Bluedog225]

Thank you both.

I’m going to restate it like I’m 5 to test my understanding. Without using any terms I don’t firmly understand.

I’m going to run a copper wire and connect the following:

1. The solar panel frames.
2. The two ground points on the Quattro.
3. The frame of all MPPT charge controllers.
4. The negative bus bar of the Victron Lynx distributor (that is attached to the battery negative lead).
5. The metal rack and unistrut inside the conex.
6. The server rack battery frame.
7. The metal shelves housing the batteries.

And when the conex is in its final location, I am going to drive two copper clad grounding rods, connect them together with a copper wire. Then I will connect the grounding rods to the negative bus bar of the lynx distributor.

PS-There will never be shore power.

PPS-There will be a generator that has no connection to the earth.

I really trying to get this stuff. Any feedback appreciated.

 

[Hedges]

Sounds good.
It may be that including battery negative terminal of Lynx in the ground network is correct. I would expect so, just haven't used that brand.


does generator bond neutral to ground? If not it can inherit that from your system. So long as your inverter doesn't switch and bond neutral as is standard for mobile systems.

Maybe if you ever use generator stand-alone, and it doesn't have neutral bonded, you could make a cord/plug that provides that.

 

[Bluedog225]

Dang Hedges. I wish I understood any of that. ?

Ok, maybe I get a bit. The generator manual seems no help. It just describes both conditions (I think).

I don’t know if using a grounded plug means I “borrow” the ground from my system. Is that what you mean?

Thanks

 

[timselectric]

It is recommended to have a reference potential of 0 Volts. Technically a chassis is not a true earth potential though..

So ambulances and buses have a small grounding strap to dissapate excess charge accumulation from chassis. It happens.

Yup
This is for static discharge. Also a good thing to have.
I only talk about electrical safety grounding. Because, if it's all done correctly. You get the static control as an additional benefit.

 

[timselectric]

I don’t know if using a grounded plug means I “borrow” the ground from my system. Is that what you mean?

If your generator has built-in bonding. You don't want to connect it to a bonded system. This makes you have two N/G bonds. Which puts neutral current on the ground conductor.
But this all depends on your system and generator. And how they are wired and connected together.
A "grounding plug" is used to create a N/G bond on generators if needed.
You can buy one or make your own. It's just a male cord end without a cord. Inside, there is a jumper between the neutral and ground terminals.
But again, this all depends on the individual situation.

 

[Bluedog225]

That makes sense. But I can’t tell from the generator manual (above) whether it is bonded or not.

It’s a champion dual fuel. In the 8000-9000 range. I will try to research. Seems like they should say one way or the other.

 

[featherlite]

Seems like the conex is the same as a recreational vehicle.

Given that the typical RV has rubber tires and is isolated from the "earth, and assuming that the subject conex is in contact with the earth, do any of the answers provided so far on this thread respecting the conex need to be modified in the case of the typical RV?

 

[timselectric]

That makes sense. But I can’t tell from the generator manual (above) whether it is bonded or not.

It’s a champion dual fuel. In the 8000-9000 range. I will try to research. Seems like they should say one way or the other.

It's easy to check for continuity between the neutral and ground terminals.
Or use a receptacle tester, while the generator is running. (And nothing else connected to it)

STEREN HER- 258, 110-125 Volt AC 3 Prong Receptacle Wall Outlet Circuit Tester with Indicator Lights for Households, Homeowners, Wall Plugs, Outlets, DIY, Broken Circuits, and Fuses by STEREN https://a.co/d/dgijQrj

 

[timselectric]

Given that the typical RV has rubber tires and is isolated from the "earth, and assuming that the subject conex is in contact with the earth, do any of the answers provided so far on this thread respecting the conex need to be modified in the case of the typical RV?

No
Because it's not an RV. And shouldn't be thought of as one.

 

[featherlite]

No
Because it's not an RV. And shouldn't be thought of as one.

The question was "do any of the answers provided so far on this thread respecting the conex need to be modified in the case of the typical RV". Are you answering the question with "no"?
I am not disputing, just trying to learn.

 

[timselectric]

The question was "do any of the answers provided so far on this thread respecting the conex need to be modified in the case of the typical RV". Are you answering the question with "no"?
I am not disputing, just trying to learn.

Yes, my answer was "no".
Sorry for the confusion.

 

[featherlite]

Yes, my answer was "no".
Sorry for the confusion.

I am the one who is confused.

If the answer is "no", then you are saying that there is no difference between grounding an RV and a conex. Correct?
The reason I am confused is I thought that solar panels mounted on the roof of a house or mounted on the ground needed to be bonded to the earth with a ground rod. A ground rod is not practical in a mobile RV.

 

[timselectric]

The reason I am confused is I thought that solar panels mounted on the roof of a house or mounted on the ground needed to be bonded to the earth with a ground rod. A ground rod is not practical in a mobile RV.

Solar panel frames should be bonded to the electrical grounding system.
Not a ground rod. That's just earthing. And does not provide electrical safety from shock.
The earth is not a good conductor. And wouldn't provide a good return path for fault current, back to your electrical grounding system.