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karlw 05-19-2016 02:36 AM

RV Breaker Panel vs Home Breaker Panel
 
I am researching around the internet and notice that most conversions seem to be using a 120v breaker panel that is combined with 12v, designed specifically for RVs. I bought a 120v breaker panel from home depot designed for homes and am intending to buy a separate 12v fuse board for everything else, primarily because nearly everything in my conversion is going to be 120v except those things that require 12.

My questions are, is it illegal to use a house breaker panel? Is there any reason I should consider a panel designed for RVs? Any recommendations?

Timelord 05-19-2016 02:51 AM

My understanding is that such designs are usually for size constraints or convenience rather than anything to do with legality.

superdave 05-19-2016 07:25 AM

there will be a little green screw with that breaker box, DO NOT bond the neutral with the ground. the ground bus bar should be bonded to the frame. wire everything as you would a house. if you have a on board genny the nuetral and ground are bonded at the genny from the factory, on most models.

EastCoastCB 05-19-2016 07:55 AM

Quote:

Originally Posted by superdave (Post 148481)
there will be a little green screw with that breaker box, DO NOT bond the neutral with the ground. the ground bus bar should be bonded to the frame. wire everything as you would a house. if you have a on board genny the nuetral and ground are bonded at the genny from the factory, on most models.

Love the avatar!!:thumb:

jester 05-19-2016 08:15 AM

just finished wiring mine this am. i went with the 12v and 110 combined . this makes it possible to safe space and have all wires close.
no legalities involved that i know of.
if you gonna have your battery bank near the panel then just get the combined one to save yourself the hassel, if it not close to bank then you will want the 12v panel seperate any way in order to keep runs short. plus the combined looks very clean and easy access when finished. its all about space,
here is the one i went with https://www.amazon.com/WFCO-50-Servic...ilpage_o09_s00

turf 05-19-2016 09:01 AM

i have the WFCO box and i wish i got something a bit better.


check out blue sea marine for some nice high quality DC power distribution components.

https://www.bluesea.com/

good luck

Docsgsxr 05-19-2016 09:08 AM

I am doing the 120V house breaker as well. I am running a separate line from the batteries directly to an automotive fuse panel with an inline shut off for 12v things. and then all my 12V will have fuses to protect them.

2kool4skool 05-19-2016 10:24 AM

120v house panel and separate 12v with auto fuses. I use a 15a smart charger for the 4 100ah batts...does double duty if I need something else charged. 200w solar kicker too.

https://www.skoolie.net/attachments/p...0daf3ef935.jpg

jester 05-19-2016 01:39 PM

on side note, i ground a nice shiny spot on the rail the seats were attached to along bottom of wall to use for ground. good spot , bad spot?? isn't that technically the chasis? or should i ground elsewhere?

family wagon 05-19-2016 03:51 PM

Depends on what's being grounded, or in other words, how good the connection needs to be. Remember you're building an electric circuit. I'll suppose you're talking about "ground" as in the negative battery return. People are pretty good at seeing the positive side of the circuit: the battery post, clamp, heavy wire with lugs on both ends, fuse box, smaller wire going out to the load. The negative/return half of the circuit tends to be invisible. From the load you might have a short wire, a ring terminal, a sheet metal screw holding it to some body panel, a combination of sheet metal screws, bolts, and rivets holding a series of body panels together, somewhere a braid or heavy wire with lugs and bolts or screws connecting a body panel down to the frame, and finally a heavy wire with lugs and bolts connecting the frame back to the battery.

People forget all about those connections between the body components; they think of the chassis/body as a single unit. Electrically it isn't, though: anything that isn't welded together has a connection that may become loose, dirty, etc. When somebody is being really careful, perhaps because they're installing a radio transceiver or audio equipment, it's sometimes necessary to actually install jumpers between everything that isn't welded because though the mechanical connection is reliable, the electrical connection may not be. Common parts include door panels, the hood, fender panels that aren't welded, etc.

A shiny spot on the chair rail "could" be a good place for a ground.

cadillackid 05-19-2016 05:14 PM

so I have a question... isnt it a bad scene to be grounding your 110 volt panels to the same frame that alot of your 12 volt stuff is grounded to? shouldnt you be running grounds to each appliance / receptacle.. and then WIRING a ground to the Generator or to the Shore power connection? and leave the Bus frame for the 12 volt stuff?
-Christopher

family wagon 05-19-2016 09:17 PM

Nope. If there's going to be an ac system installed in the bus, just like any other metal building construction, the safety ground should be connected to the bus body. Without that connection devices like ground fault interrupters and over-current circuit breakers can fail to operate, ie fail to clear some types of faults by automatically disconnecting the power.

Incidentally some inverters (specifically the Xantrex PROwatt model I have) instruct that their cabinet, which is connected to the ground pin on the built-in 120v receptacles, should be connected to the dc negative/ground. When I bench tested that inverter I learned the reason for this: left unconnected its chassis floats at 60v relative to the dc input. When an unsuspecting person rests one hand on the chassis and touches either battery connection with the other hand, it results in a pretty good shock!

Robin97396 05-19-2016 10:10 PM

That sounds better than a car alarm. The old guys used to do that with model T coils to keep people from sitting on their car hoods.

dadelay 05-19-2016 10:37 PM

We've got the RV type, and it works pretty well. It's got a built in 3-stage charger that's completely automatic. We really don't even think about it. The biggest drawback is that it would be nice to have a few more 120v. circuits. We've got it maxed out with double breakers. That takes care of everything that we've got, but if we ever decide to add a circuit we're pretty much out of luck. I guess either way has plusses and minuses.

Piersg 05-25-2016 07:42 PM

Quote:

Originally Posted by family wagon (Post 148670)
Nope. If there's going to be an ac system installed in the bus, just like any other metal building construction, the safety ground should be connected to the bus body. Without that connection devices like ground fault interrupters and over-current circuit breakers can fail to operate, ie fail to clear some types of faults by automatically disconnecting the power.

OK, now I'm officially confused! I was under the impression that the grounding was done via the incoming shore power and not to the bus frame. I just bought a Progressive Dynamics 4560 All in One center, and the installation guide that came with it (https://www.progressivedyn.com/pdfs/110030%20English.pdf ) shows the panel's ground bar being wired to the incoming ground connection. It does not show a ground connection to the bus body?

Another reason for my confusion is that grounding it to the bus would not seem to accomplish much as the bus itself is isolated from the ground by the rubber tires..

jester 05-25-2016 07:48 PM

Quote:

Originally Posted by Piersg (Post 149955)
OK, now I'm officially confused! I was under the impression that the grounding was done via the incoming shore power and not to the bus frame. I just bought a Progressive Dynamics 4560 All in One center, and the installation guide that came with it (https://www.progressivedyn.com/pdfs/110030%20English.pdf ) shows the panel's ground bar being wired to the incoming ground connection. It does not show a ground connection to the bus body?

Another reason for my confusion is that grounding it to the bus would not seem to accomplish much as the bus itself is isolated from the ground by the rubber tires..

you still need to be thinking about a ground for when you arent plugged into shore. ie only running off your batteries. it does show it in your manual, your hardware has the "optional chasis ground in it" your main breaker hold down screw goes right over it. i think:biggrin:

family wagon 05-25-2016 08:00 PM

Quote:

Originally Posted by Piersg (Post 149955)
OK, now I'm officially confused! I was under the impression that the grounding was done via the incoming shore power and not to the bus frame. I just bought a Progressive Dynamics 4560 All in One center, and the installation guide that came with it (https://www.progressivedyn.com/pdfs/110030%20English.pdf ) shows the panel's ground bar being wired to the incoming ground connection. It does not show a ground connection to the bus body?

Right. Well, kind of. The ground-to-neutral "bond" connection is done for you in the shore power system. I'm not in a position to speak for Progressive, but I could at least speculate they don't mention connecting the panel's ground bar to the vehicle body because they're working in a world where RVs are made of wood, not metal. Of course it wouldn't make any sense to wire a wood body to the ground bar.

Quote:

Originally Posted by Piersg (Post 149955)
Another reason for my confusion is that grounding it to the bus would not seem to accomplish much as the bus itself is isolated from the ground by the rubber tires..

That's part of the reason why it's important. Though even if it sat on steel wheels, or had metal stabilizer jacks down, it would still be a poor electrical connection to earth.

Have you seen Mike Sokol's No Shock Zone writings? They're pretty good. His part IV addresses "Hot Skin" and part VII addresses "GFCI Theory"; both are relevant to why the bus body should be well grounded.

Piersg 05-25-2016 08:02 PM

Quote:

Originally Posted by jester (Post 149956)
you still need to be thinking about a ground for when you arent plugged into shore. ie only running off your batteries. it does show it in your manual, your hardware has the chasis ground in it. i think:biggrin:

The DC side is grounded to the chasis, I understand that, and I can see an inverter being grounded if needed, but I think the panel itself is not grounded.

Piersg 05-25-2016 08:15 PM

Quote:

Originally Posted by family wagon (Post 149960)
Right. Well, kind of. The ground-to-neutral "bond" connection is done for you in the shore power system. I'm not in a position to speak for Progressive, but I could at least speculate they don't mention connecting the panel's ground bar to the vehicle body because they're working in a world where RVs are made of wood, not metal. Of course it wouldn't make any sense to wire a wood body to the ground bar.


That's part of the reason why it's important. Though even if it sat on steel wheels, or had metal stabilizer jacks down, it would still be a poor electrical connection to earth.

Have you seen Mike Sokol's No Shock Zone writings? They're pretty good. His part IV addresses "Hot Skin" and part VII addresses "GFCI Theory"; both are relevant to why the bus body should be well grounded.

OK, just read through this thread (https://www.skoolie.net/forums/f10/ho...-ac-448-6.html ) again, and downloaded no shock zone. Confusion is cleared up.

ol trunt 05-25-2016 09:15 PM

The no shock zone should be mandatory reading for all us bus nuts!!!!!!

If you are using a portable generator like Honda or Yamaha you will need to change their floating grounds so that they ground back to themselves. Many portable generators have a ground lug on the control panel that the mfg suggests you wire to a grounding rod---how likely is that going to be? You can find a listing of generators with floating grounds and how to make their grounds go back to the generator rather than a ground rod. With a floating generator ground, it is possible for the "skin" of the bus to become hot (electrified). Under those conditions, should you happen to step out of your bus onto wet ground while you are still, say, hanging onto the step rail, you get to be the ground----a shocking (and potentially deadly) experience.:nonono: Jack

family wagon 05-26-2016 01:21 PM

I did an idiot thing once. Well, that has happened more than once, but there's one occasion in particular which I'll share now. :thumb: I wanted to test a portable generator powering the house. I've done this before without incident, but having traded out that former generator for a smaller unit, wanted to test again. We had moved to a different house, too. Anyway I wired the 240 volt hookup with a 3-wire cord because I was backfeeding through the electric range socket which had 3 conductors. The generator of course had the 4-wire L15-30 connector... unfortunately I connected the house ground, which I knew would be bonded to the house neutral back at the main panel, to ground on the generator's L15-30 rather than neutral. This generator doesn't have a built-in bond. It only took a few seconds to figure out that because the neutral was disconnected, some parts of the house were experiencing well over 120 volts while other parts were well under. Fortunately the "double check the neutral and ground!" lesson tuition only cost me one fluorescent ballast, a handful of CFL lamps, two surge suppressors, a wall-wart transformer, and the ice maker in the freezer. It could have been much worse.

skoolie_n00bie 05-26-2016 01:56 PM

This is what i'll be using.
Very high-tech...I think McCoy left it behind....

Piersg 05-26-2016 05:15 PM

Ok, so just to clarify this in my mind, when I install my PD4560 50 Amp all in one center, I'm going to run a green wire from the grounding block to the frame/chassis of the bus, like in the diagram below (I added the green):

https://www.pdgnetworks.com/images/bus/grounding1.jpg

Does this look right?

Thanks!

Jolly Roger 05-26-2016 06:11 PM

Quote:

Originally Posted by ol trunt (Post 149970)
The no shock zone should be mandatory reading for all us bus nuts!!!!!!

If you are using a portable generator like Honda or Yamaha you will need to change their floating grounds so that they ground back to themselves. Many portable generators have a ground lug on the control panel that the mfg suggests you wire to a grounding rod---how likely is that going to be? You can find a listing of generators with floating grounds and how to make their grounds go back to the generator rather than a ground rod. With a floating generator ground, it is possible for the "skin" of the bus to become hot (electrified). Under those conditions, should you happen to step out of your bus onto wet ground while you are still, say, hanging onto the step rail, you get to be the ground----a shocking (and potentially deadly) experience.:nonono: Jack

I was trying to play catch up and read all the post before I commented but TRUNT and I still have not read the no shock zone.
For government construction we are required to use a grounding rod for any portable generator,welding machine and most BS it buy driving a piece of steel whatever in the dirt to look like something and hook jumper cables from rod to equipment frame.
All generators are vibration isolated but have steel bolts through the isolators to the frame but have a ground to frame but as stated it could be unreliable.
For me a ground rod driven into the ground at least 18" and a good sized ground wire connected to the generator ground lug not the frame lug and clamped to the rod is true protection.
With all of that said and everything we do to these busses? Has anyone ever thought about grounding the bus body and a rod on the roof for lightning protection? Because even though the frame is isolated with tires the body is isolated from the frame to an extent?
Laugh if you want to.
Government/base high rise construction they come up with all kinds of electrical safety issues among other things?
I am usually a water man but my company involved me in electrical solar panels on a 5-story metal roof and I had to add seperate lightning protection because lightning looks for a path to ground and all the power from these panels are grounded. And because I was the installer of 70+ panel solar water system I had to install lighting protection on them as well? (Not the owner of the company just the ramrod installer) sucked either way. Water piping does create a path to ground and We did use copper for the glycol/water system so had to ground the piping on the roof and on the first floor at the equipment? Probably over kill but it has put food for thought in my head as far as grounding in/on my all metal structure bus? And what to ground where? Lightning if grounded to the body could blow everything you have including you,unless it is provided a direct path to ground? Ain't scared of it but I swear growing. Up as a kid in texas my DAD was a lightning rod never hit directly but close enough to cause temp. Blindness and 1 time it was because he came to close my bedroom winder after I ignored mom telling me to. I jumped and said ok I got it dad and as soon as he touched the winder the lightning was close enough it temp.blinded both of us? My first but his third?

family wagon 05-26-2016 07:00 PM

Piersg: yes that looks good.

ol trunt 05-26-2016 10:17 PM

FYI Trunt has read and understands the "No shock zone" So what's the prob?

jester 05-27-2016 04:24 PM

Quote:

Originally Posted by ol trunt (Post 150182)
FYI Trunt has read and understands the "No shock zone" So what's the prob?

i can attest to this, he has heard my ideas for fishing worm gathering and concluded it was indeed very dangerous and very mucho in the shock zone.:rofl:

Jolly Roger 05-27-2016 04:59 PM

Quote:

Originally Posted by ol trunt (Post 150182)
FYI Trunt has read and understands the "No shock zone" So what's the prob?

Sorry TRUNT/sir i just read my last post and I made it sound like you havent read or dont know? i am sorry. that wasnt my intention?? i started out posting in one direction and didnt start completely over when i changed direction? I meant to say that you had hit on a topic that i had debates in my head about and went on to explain my debates and didnt see that i had thrown you UNDER THE BUS? SORRY. i will make it to the NO SHOCK ZONE this weekend to answer the questions in my head about grounding.
No problems here sir.
Thanks for your time.

jester 05-27-2016 05:22 PM

lol no inside joke or anything, i was tellin trunt the other day on different thread that i had wired a male to male extension cord to test my ac circuits, BAD idea. so i said id use it for a worm gathering aid and stick it in ground for a bit then go get the worms that had run for the hills!!

TAOLIK 05-27-2016 05:33 PM

Question: how many switches do you guys use on your breakers and how many watts is your electrical system? I know it's need based but I am curious. I have a RV breaker with a few switches that I am thinking about hooking up, but was wondering about this the other day.

My system will be 1000watts with a small generator so I don't know if I need more than a few switches. 1 for the occasional heavy load like the wife's hair dryer, 1 for the kitchen, 1 for the livingroom and bedroom?

The-Breeze 08-24-2016 11:48 PM

NO SHOCK ZONE for those interested:

https://noshockzone.org/15/

or......

https://www.skoolie.net/forums/f10/rv...fety-7862.html

Soaringcook 09-24-2021 09:12 PM

Rv panel vs home subpanel
 
Hi all,

What the difference in wiring an rv 120v panel and a home subpanel?

Hiyu 09-26-2021 10:52 PM

I just installed a PD 4100, AC DC with a battery charger, piece of cake and it exceeds all my nees!

Rwnielsen 09-26-2021 11:09 PM

Quote:

Originally Posted by cadillackid (Post 148618)
so I have a question... isnt it a bad scene to be grounding your 110 volt panels to the same frame that alot of your 12 volt stuff is grounded to? shouldnt you be running grounds to each appliance / receptacle.. and then WIRING a ground to the Generator or to the Shore power connection? and leave the Bus frame for the 12 volt stuff?
-Christopher

Short answer, yes. Don't ground your 120 volt to the bus unless the bus is grounded ie: ground rod or grid. Otherwise you may be standing outside, possibly wet and complete the ground circuit. The dreaded hot skin scenario

Rucker 10-01-2021 05:39 PM

Quote:

Originally Posted by Rwnielsen (Post 454350)
Short answer, yes. Don't ground your 120 volt to the bus unless the bus is grounded ie: ground rod or grid. Otherwise you may be standing outside, possibly wet and complete the ground circuit. The dreaded hot skin scenario

This questions keeps coming up, so help me understand this a little better.

From all of my research it's perfectly okay to ground both 12VDC and 120VAC systems to the chassis frame and in fact preferable. For the DC, the ground is the return path to your battery negative terminal-no issues sharing the AC ground because, well, AC circuits are not completed anywhere in the DC circuit. They only complete with the neutral conductor of an AC circuit, or under a fault condition, which is real but rare.

When powered by shore power, the 120 V AC lines with a ground wire connected to the chassis acts as a conductor back to the shore power ground rod under a fault condition. Normally it doesn't have any voltage potential but if it did you really want it to drain off that way, not through your body to literal ground, which is the only path it would have if you don't bond your AC ground to chassis.

Of course, if shore power ground is not grounded then all that potential from a short is just sitting there waiting for you to grab the bus. A real scenario, but much less likely than a short from the hot wire to metal on your bus (or less common but certainly dangerous reverse polarity bootleg ground: Are "Little" Shocks OK? | No~Shock~Zone ); and without that chassis ground to shore power ground you're gonna feel that.

For generator power it is the same principle. I have less experience with them but from what I've read it is smart to ground the generator (yes, I know, nobody does that. And it's also true we don't often see short conditions. So 'I've never grounded my generator and never had a problem' is not a statement to rely on)

Here's the relevant link on grounding from the no-shock zone that's my go-to source for a lot of this info: Generator Ground-Neutral Bonding | No~Shock~Zone

Am I missing something?

rossvtaylor 10-01-2021 11:49 PM

Looks to me like you've got a good handle on it, Rucker. In another thread...or maybe this one earlier?...I did mention parking on a ground plate or using a short stake to provide an "Earthed" ground when parked. But like you said, nobody does that in real life. Regardless, it sounds like your understanding of all this is thoroughly grounded.

NOWHERE13 10-11-2021 11:03 PM

Hello, Article 551 in the NEC covers grounding for us pretty good.

Rucker 10-11-2021 11:24 PM

Quote:

Originally Posted by rossvtaylor (Post 454905)
Looks to me like you've got a good handle on it, Rucker. In another thread...or maybe this one earlier?...I did mention parking on a ground plate or using a short stake to provide an "Earthed" ground when parked. But like you said, nobody does that in real life. Regardless, it sounds like your understanding of all this is thoroughly grounded.

Trying to think of a clever comeback to your play on words, but I fear I might become a lightning rod for jokes!

Rwnielsen 10-12-2021 06:03 PM

Quote:

Originally Posted by cadillackid (Post 148618)
so I have a question... isnt it a bad scene to be grounding your 110 volt panels to the same frame that alot of your 12 volt stuff is grounded to? shouldnt you be running grounds to each appliance / receptacle.. and then WIRING a ground to the Generator or to the Shore power connection? and leave the Bus frame for the 12 volt stuff?
-Christopher

Yes
Single point ground, at the source, either generator, shore power, wind, solar.... The NEC does not allow multiple grounding. I've tried to explain, to deaf ears, too many times to get involved.

NOWHERE13 10-12-2021 06:49 PM

Hello Rwnielsen, check out Article 551.56 A-D.

NOWHERE13 10-12-2021 07:00 PM

Often times we confuse "grounding" with "bonding". Check out Article 551.56 a-d

Rwnielsen 10-12-2021 08:53 PM

Quote:

Originally Posted by NOWHERE13 (Post 455846)
Hello Rwnielsen, check out Article 551.56 A-D.

I did, what's your point?

Rucker 10-12-2021 09:25 PM

Quote:

Originally Posted by Rwnielsen (Post 455843)
Yes
Single point ground, at the source, either generator, shore power, wind, solar.... The NEC does not allow multiple grounding. I've tried to explain, to deaf ears, too many times to get involved.

Either I'm misunderstanding your answer here or we disagree completely on what's correct.

In this context I'm pretty sure when you say ground, you mean in a more technical sense 'common reference voltage', where the neutral wire and the ground wire are connected together, or bonded. Let me know if I've got that wrong. And although I don't have access to the references Nowhere13 mentions I'm guessing it states pretty much what you and I understand: nowhere in the rig should the neutral (typically white) wire and the green or exposed ground wire be connected together. The only place where those two wires should have a normal connection is all the way back to the panel, where the neutral wire and ground wire are bonded and there's a rod stuck in the ground. If using a generator, the neutral and ground MAY be bonded at the generator or not, but that is the only place where they should be connected, and nowhere in the rig should the neutral and green wire connect together.

There. Got that out of the way.

None of this though relates to grounding of devices, nor to connecting the ground wire of an AC circuit to the chassis of the bus. An AC device ground is essential for providing a path for current under fault conditions and, if not connected, poses a huge risk to you.
All AC devices in your rig should have a grounding plug, and that is the key to not getting electrocuted where a fault condition exists with the device. If there is a short circuit in the device and you touch a conductive part of that ungrounded device it you will get a zap somewhere between a tickle and a fatal to the degree that you conduct to ground. Very bad scenario.

If that device is grounded, you will only get a zap to the degree you form a better circuit to ground than the ground wire does. Much better scenario for you.

But if you have not grounded the chassis of your rig to that ground wire going back to shore power, and if the short is to a conductive surface on the rig, like for instance where a grommet has failed and the black wire is chafed through on a hat channel, you are right back up there in the very bad scenario. You will you will get a zap somewhere between a tickle and a fatal to the degree that you conduct to ground, just as you would with that ungrounded device. I suggest that if you believe in grounding your devices, you should also believe in grounding the chassis of your bus.

One more time: grounding the chassis of the rig to the AC ground circuit is essential for providing a path for current under fault conditions where the AC hot wire has come into contact with a conductive surface of the bus itself, because even though you potentially form a better circuit to ground than the ground wire does, without that chassis ground to negative you form the best circuit.

Importantly, for the DC lines, the return path to the shore power bonded ground exists, but only as an open circuit. It does not complete back to the negative terminal of the battery. Likewise, touching the negative terminal of the battery does not complete any circuit on the AC lines.

So to Cadillackid's question, the answer should be no: none of this precludes using the rig chassis for the return path of a DC circuit.


I note that his question was asked like a bazillion years ago, but getting the answer right, especially with a new crop of forum members, is pretty important.

NOWHERE13 10-12-2021 09:56 PM

It is not my point. Just providing information. Safe travels and stops!

DeMac 10-12-2021 10:05 PM

I concur
 
Rwnielsen & Rucker interpret all of the sections together. I concur with you both, different terminology. Hard to explain shortly, right?

The first four Chapters of the NEC apply to all installations. Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).

Article 551 amends the Chapter Three wiring methods; it does not replace them. Where Article 551 is silent, Chapter 3 requirements apply [551.47(A)].

Do not ground interior electrical equipment. Where 551.55 speaks of "grounding," it means "bonding." If we review these terms in Article 100, we will see the terminology error when reading the requirements. Make sure you bond, not ground, interior equipment.

Bonding conductors for non-current carrying metal parts must be at least 8AWG [551.56(C)]. Number 8 eliminates differences in potential. If reliability is the concern, use bonding jumpers around raceway connections instead of simply upsizing bonding conductors.

Don't use the grounded conductor (neutral) as an equipment bonding conductor [551.76(D)]. This applies to all circuits, not just RV ones. The reason is the neutral (which is, at these voltage levels, the grounded conductor) carries the unbalanced current back to the source. It does not provide a low impedance path for eliminating differences of potential. Confusion here can result in a lethal touch shock.

Don't connect the grounded conductor to a grounding electrode on the load side [551.76(E)]. Actually, don't connect anything on the load side to any ground electrode; such a connection serves no electrical purpose.

What's the difference between bonding and grounding? Grounding electrode or grounded conductor?
Look in the NEC, Article 100.
Does the NEC refer to grounding incorrectly in any of its articles? Yes! So apply the Article 100 definitions. Don't ground where you should bond.

Rwnielsen 10-13-2021 02:50 AM

Quote:

But if you have not grounded the chassis of your rig to that ground wire going back to shore power, and if the short is to a conductive surface on the rig, like for instance where a grommet has failed and the black wire is chafed through on a hat channel, you are right back up there in the very bad scenario. You will you will get a zap somewhere between a tickle and a fatal to the degree that you conduct to ground, just as you would with that ungrounded device. I suggest that if you believe in grounding your devices, you should also believe in grounding the chassis of your bus.
I wasn't referring to a bad shore power connection. All bets are off if you're hooked up to a faulty electrical system.

This makes sense until you think about where your second point of contact is. I regularly handle hot wires but I'm very much aware of what I'm touching. Your bus (except when plugged into a grounded source) is an isolated electrical system. Ground in the normally accepted sense doesn't exist. Your neutral and ground are connected at the source. Most panel enclosures are bonded through the ground buss. Isolated ground busses exist but are generally supplemented with a standard ground buss and used in 'clean power' applications.
You should never hook up to shore power with an open ground.

Rwnielsen 10-13-2021 02:56 AM

I'm about out of gas on this subject. Someone in an earlier post said to ground your panel's ground buss to the chassis. This is not correct.

Rucker 10-13-2021 12:05 PM

Quote:

Originally Posted by Rwnielsen (Post 455897)
I'm about out of gas on this subject. Someone in an earlier post said to ground your panel's ground buss to the chassis. This is not correct.

I can't say I don't disagree.

Soaringcook 10-13-2021 12:12 PM

Easy
 
If people understood "path of least resistance and gfci breakers better, this wouldn't be so confusing.

Rucker 10-13-2021 03:46 PM

Quote:

Originally Posted by Rwnielsen (Post 455896)
I wasn't referring to a bad shore power connection. All bets are off if you're hooked up to a faulty electrical system.

This makes sense until you think about where your second point of contact is. I regularly handle hot wires but I'm very much aware of what I'm touching. Your bus (except when plugged into a grounded source) is an isolated electrical system. Ground in the normally accepted sense doesn't exist. Your neutral and ground are connected at the source. Most panel enclosures are bonded through the ground buss. Isolated ground busses exist but are generally supplemented with a standard ground buss and used in 'clean power' applications.
You should never hook up to shore power with an open ground.

Thanks for this. This is a super important topic.

If I understand your comment, the concern is when a bus is NOT connected to shore power, where there is no apparent ground (your words: 'an isolated electrical system'). I had trouble making sense of the second part of your comment 'most panel enclosures are bonded through the ground bus'. They are not--you need to put in the green screw to bond them, or take it out if it's screwed in. Maybe that's what you meant.

Here's my understanding: ground does exist. If your bus has an inverter (an independent 120 VAC-producing device) the inverter itself should have neutral and ground bonded together when running independent of shore power. That's what I understand is meant by 'at the source', and that's why I say house power via inverter is (or should be) grounded.

When inverting from battery power, the bond should be complete, or connected, so there is a return path for any short. When connected to shore power (or when a charger/inverter is powered by shore power) the bond should be open so that the source (shore power) is the single point of ground.

It appears that many charger/inverters out there don't clearly indicate how they handle ground and ground/neutral bonding. Without clear specifications you need to verify your own inverter's operation to ensure proper grounding under all circumstances.

Here's my setup: I have a straight-up inverter with a permanently bonded neutral/ground. I don't need to worry about how the ground and neutral are handled because when I plug in to shore power my inverter hot and neutral route from the inverter ONLY to the GoPower switcher and are disconnected in the presence of shore power. This is one more reason why I like discrete devices instead of combo units. If I had a charger/inverter I'd need to understand how that thing is handling ground. I charge with a separate Doco charger.

The reason for having that bond between neutral and ground on an inverter is the same as for shore power: the inverter is the 'source'.

(It's the same principle with generators-you need to ensure neutral and ground are bonded at the generator itself. I'm no expert and don't understand a lot of the discussion in the forums about floating ground and special circumstances, and GFCI tripping failures and the like. I hope to get more educated in this forum and through my own research.)

It's also why inverters, like all other electrical devices, should be grounded to the bus chassis. If a fault in the circuit electrifies the bus chassis, you stand a better chance of being less conductive than the ground wires running back to the inverter.

And, since there is no 'earth ground', you don't complete any circuit by standing in a mud puddle and touching a conductive surface on the bus due to a fault in the inverter power-again, when running solely on house batteries driving the inverter.

(It's a different thing if you are running a generator with a frame ground --that is more like a shore power scenario and why you'd want every device to ground to the chassis, and the chassis back to the generator).

This is my understanding to date. If I've gotten something wrong though I'm all ears!


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