Complete Off Grid Grounding??? some Questions

[12VoltInstalls]

Is there any NEC reference to RVs?

I personally don’t know, but indirectly I believe there are specific minor references for modular or manufactured housing and mobile homes. My recollection from some past thing I don’t recall the source of is that RVs in some situations and/or jurisdictions fall under “manufactured housing” for code purposes.
I never finished apprenticeship but very early in my career I did work for two different licensed electricians. So my memory could be incorrect, and I can’t say either of them would function well in today’s code-heavy world.

I mentioned RVs just because of the little divergent question that slipped in. Either way the principle is the same as you pointed out.

 

[Zil]

I personally don’t know, but indirectly I believe there are specific minor references for modular or manufactured housing and mobile homes.

I mentioned RVs just because of the little divergent question that slipped in. Either way the principle is the same as you pointed out.

That post was directed to RandyP post 38 answering questions he asked me.

 

[svsagres]

RandyP. can you provide a link to NEC that addresses off-grid electrical system 'grounding'. especially inverters if available? thanks

NEC doesn’t care whether you’re on or off grid; the rules are the same assuming we’re talking about 120/240 AC in a permanent structure. I work with a large off-grid site in WA, and we have to have everything inspected by our county AHJ, pull county permits, etc…

It’s even more complicated for us because our distribution system is designed as though it’s a PUD, but since it isn’t different rules apply, which conflict (6 throw rule being the main one we’ve argued with our AHJ).

 

[RandyP]

Do you think that your body is of a lesser or greater resistance than the generator frame?
1) Electrical paths follow the path of least resistance.
2) if wired properly the RV should be have the N/G automatically or manually disconnected from the on-board circuits when the transfer switch or cord is moved from one source to another. So your body completing a circuit to G/ground/bare/green/earth shouldn’t ever occur.
3) GFCI breakers are not so expensive that one couldn’t incorporate them if you think there’s a problem. Then the only unprotected part of the circuit is the generator cord to the transfer switch

from your comment:
"1) Electrical paths follow the path of least resistance."
This is absolutely NOT TRUE. Electrical current follow ALL paths back to the source. Called Parallell paths.
The path current is inversely proportional to the resisstance of the path (approximately). The most current flows thru the path of least resistance, but current also flows thru all paths available.

There are other FALSE common beliefes that need to be corrected. Mike Holt does an excellent job of explaining these.
Myth number 2, check it out.

 

[WYtreasure]

There are other FALSE common beliefs that need to be corrected. Mike Holt does an excellent job of explaining these.
Myth number 2, check it out.

THANK YOU RandyP
Once again I say MIKE HOLT ROCKS.

Myth #4) More grounding the better = FALSE
11:30 Overseas equipment manufacturers instructions
15:15 Generator grounding
17:00 SOLAR ARRAY GROUNDING

 

[12VoltInstalls]

"1) Electrical paths follow the path of least resistance."
This is absolutely NOT TRUE. Electrical current follow ALL paths back to the source. Called Parallell paths

I should have written that differently
Of course you’re correct technically and empirically.

The point was: in practical terms a generator on the ground shouldn’t or is not likely to result in a shock to a human that’s not barefoot on briny soil
GFCIs would assure that didn’t happen.

 

[RandyP]

Why should occupied buildings have a system Grounding Electrode, Equipment Grounding Conductors EGC (ie: all metal enclosures, sufaces need to be connected with EGC's and then to the Grounding Electrode at one point only).
Check this out:
Starting at 23.00 in this video:

Regardless of electrical system type (AC or DC) an occupied building needs an equipment grounding system and one grounding electrode.

Starting at 33.35 in this video.

Even for DC off grid systems, near by lightning strikes (High energy discharges) can cause side discharges in the building between electrical conduction (metal) enclosures and possibly people.

Here it is again, stated more precisely:

 

[RandyP]

Equipment grounding vs system grounding. All Electrical systems in buildings, AC,DC, Ungrounded systems or Grounded systems need to have Equipment grounding:
Starting at 33.35 in this video:

I think this video finally displays the point I am trying to make, Equipment Grounding in Occupied Buildings can save life and property loss (fires) due to lighting strikes near (but not to) occupied buildings.
Ref: NFPA NEC 70 250.4(A)2

 

[WYtreasure]

Equipment grounding vs system grounding. All Electrical systems in buildings, AC,DC, Ungrounded systems or Grounded systems need to have Equipment grounding:
Starting at 33.35 in this video:

I think this video finally displays the point I am trying to make, Equipment Grounding in Occupied Buildings can save life and property loss (fires) due to lighting strikes near (but not to) occupied buildings.
Ref: NFPA NEC 70 250.4(A)2

I'm glad you're so persistent. It's finally sinking into my knoggin. ?

 

[RandyP]

Is there any NEC reference to RVs?

Yes. There is :
NFPA 70, NEC Article 551 Recreational Vehicles and Recreational Vehicle Parks
And
ANSI Standard RVIA-LV

There is a free view of the 2020 NEC at :
(you will have to setup an account and log in, but its free view)

NFPA 70®: National Electrical Code®

<p>90.2(C) Installations Covered.<br /><br />This Code covers the installation and removal of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables for the following:<br /><br /> (1) Public and private...

www.nfpa.org

There is a resource here on this forum for:
ANSI RVIA LV: Standard for Low Voltage Systems in Conversion and Recreational Vehicles

ANSI RVIA LV

ANSI RVIA LV: Standard for Low Voltage Systems in Conversion and Recreational Vehicles Took me the better part of two years, but I finally found a free copy of the ANSI RVIA LV. RVIA LV ("LV" = "Low VOltage) is the American RV Industry's...

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[Zil]

Thanks, RandyP

 

[12VoltInstalls]

Starting at 33.35

That was an excellent video. Holy smokes!

from your comment:
"1) Electrical paths follow the path of least resistance."

While I could have phrased that differently as I stated previously… after watching that video through I don’t think I’ll use that phrase anymore. The optimal or planned path isn’t always the (exclusive) circuit that voltage can be found, for sure. However- as Holt explained- this leads to misunderstandings in ways that I never considered before.

And I should know better! When I was 14 using my dad’s craftsman drill in the driveway every time I kneeled I would get shocked when I pulled the trigger. Obviously not a huge shock but it was pretty alarming. Nevertheless I realized what was happening was the armature or something was bleeding voltage into the aluminum body and concluded that I was a second path to ground and I was still alive because my resistance was high enough to not get the full dose.

So I guess a couple electricians I’ve used haven’t apparently seen that video.

 

[RandyP]

..................

So I guess a couple electricians I’ve used haven’t apparently seen that video.

It's a difficult concept, I'm not surprised some electricians have not grasped it yet. I am an electrician, and have not always understood this concept. It's important to personell safety. It's importand to continue to learn as you discover new information.

 

[joeblack5]

It is most amusing that the experts from different parts of the world have come up with different and opposite ideas regarding grounding that both lead to safe solutions..


J

 

[svsagres]

It is most amusing that the experts from different parts of the world have come up with different and opposite ideas regarding grounding that both lead to safe solutions..


J

In the end, only two things really matter. First, is it safe? And secondly will your AHJ sign off on it.

 

[RandyP]

It is most amusing that the experts from different parts of the world have come up with different and opposite ideas regarding grounding that both lead to safe solutions..


J

I think a big challenge in the US is terminology.
Grounding. The term seems to be all inclusive.

-There is Earth Grounding, tying an electrical system in a specific controlled way to the Earth at one point with a grounding electrode.
-There is Neutral Bonding to Ground, tying one insulated conductor of an Electrical system to the system ground.
-There is Equipment Grounding Conductor wiring, tying al metal enclosures of electrical equipment together and back to the power source Neutral Bus so over current devices will trip if a hot wire contacts the enclosure, avoiding personnel electrocution at energized equipment enclosures.
-There is bonding all electrical equipment enclosures and metal surfaces together and extending a conductor to an earth ground to discharge power induced in them by electromagnetic pulses from near buy lightning strikes that could otherwise discharge (side flash) to other conducting items with a path to ground or a person, causing a fire or electrocution.
-There is maintaining only one point of connection to earth ground to avoid issues with voltage gradients in the earth ground relative to distance from lightning strike point.

These are all called GROUNDING, no wonder there is confusion !

 

[MinnesotaGuy]

First post! I am getting conflicting answers from the "experts." I've watch Mike Holt, etc. I started from no knowledge and did put in a very nicely functioning off-grid system. (2) 200 w panels, 40 amp Rich Controller, 2000 w inverter, transfer switch for the Gen/Inverter. Everything is functioning very well, but I can't get a handle on the grounding and have read LOTS of stuff. 1) I assume there is no need to ground the 12 volt system, other than perhaps bonding the 2 solar panels and running a ground wire into a ground rod next to the panels (?), but where I am really hung up is where the inverter has a ground connection wire, the transfer switch has a ground connection wire and right now they are not connected to anything. Can (should) I hook them up to a bus bar, then run that with a ground wire to a grounding rod outside? Basically we use 12 volt for lights etc. but using the transfer switch we have a choice of using the Honda 2200i or the Inverter to run the pre-wired 120v ac system or I have a receptacle where I can plug the microwave into the line from the Generator (or the inverted for a quick coffee warm up). The silver JB is a line running from the generator receptacle, so that white duplex next to it, is where I plug in the microwave. Appreciate guidance.

 

[12VoltInstalls]

The equipment grounds are different than “electrical grounds” for 120VAC

Equipment grounds go to the batt(-) connection

The electric grounds may or may not be required to go to an ‘earth’ ground but that would be done differently depending on your setup. But you do not want to connect these to your solar panels! The solar panels are separate from both your 12V system and 120V system.

 

[WYtreasure]

First post! I am getting conflicting answers from the "experts."

Welcome to the show MinnesotaGuy.

Good luck with finding the answer to your grounding issue. There are so many ways to build a system. There is no "one size fits all" fix for all systems.
My advice is to look for the appropriate forum and start a thread with the specifics of your system. I've read many conflicting threads and posts.

More reading if you get bored and have not been there yet:

Search results for query: ground

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[RandyP]

First post! I am getting conflicting answers from the "experts." .................... View attachment 82998

First things first.
-1 Is this system in an occupied building or on a mobile platform (RV) ?
-2 Is this system ever tied into shore power (Power from an off site power source, like a public utility) ?