For those of you with both the AC and low voltage DC systems do you ground both systems to earth on the same grounding rod? Do you use two separate grounding points/grounding rods. I thought I needed to have two separate grounding rods for each system. I was going to run the AC grounding conductor from the panel through the wall to a separate grounding rod that is 10 ft away. I've read some people ground both their AC and DC to one grounding rod. What is the best and safest way. Does grounding both electrical systems together (at the rod) cause interference between the systems. This is a off-grid solar only. Thanks.
Grounding AC and DC systems to Earth
- Thread starter Jet
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sunshine_eggo
Happy Breffast!
Im by far no authority on the matter but I live full time in a 40 foot motorhome parked inside a 44x16 foot garage and get my power primarily via solar panels on the roof of the garage. Most of my system is located in the "basement" of my RV, to include controllers, inverters, battery banks (lithium primary, agm back up), and so on. The only external parts of my system are the panels and wires coming from them. Everything that is located inside my RV is grounded to the chasis of the RV. The same goes for the cable that provides 120v power to the RV. A cable that would normally be connected to a 50amp or 100amp 120v power supply at an RV campsite but is currently-and usually-connected to the inverter of my solar power system. My garage has a metal roof so Ive grounded the panels to that and the roof to one of the two copper grounding rods that my meter box is grounded to. I hope something Ive said is helpful toward answering your question. If not, hopefully someone a lot more knowledgeable about the topic than myself will come along and post. Good luck!
Anyway, to summarize what I "think" I said, is that I have everything, A/C and D/C grounded to the same RV chasis. There really isnt any other option to be honest. I could now ground the chasis to a grounding rod, I suppose. I never actually thought about that lol! But in my mind, ground is ground. Basically, a ground is used to divert wayward current into "the ground" as opposed to "into/through your body" or other things that you wouldnt want electricity to pass through. Since electricity will take the easiest path to ground, providing a direct link from source to ground via copper is usually that easiest path. I cant imagine why you cant use the same ground for DC and AC. Its just ground. But like I said, no expert here. Not even close. So hopefully a real expert will come along soon.
vbadov
New Member
That sounds pretty logical.
I like your setup. In a motorhome inside a garage that is so awesome. I've been in a motorhome for many years. Had to get solar going because they cut the power off the yard that I stay at. about 6 months ago I Got a notification from my alarm system Simply Safe. That my power went out. When I got back I finally deduced that there was no power to the main yard box. Anyway I struggled with generators for a week. Thinking they were going to turn it back on but they never did. So I had to start going solar. What a mess that was at first . I was lucky I ended up doing a halfway decent job . Anyway I've been on a 12 volt system I put together . I did a pretty good job setting it up I'm completely off grid. Now I'm going to take the next step to 48 volts. I'm doing a bunch of research to try to figure out what system exactly I'm going to do. It's a lot of work doing the research but it has to be done. N It really helps. Well. take care thanks for trying to help the people.. ?
I honestly can't wait to get it done. I'm going to have enough solar to charge my 48 volt batteries. I'll be completely self-sufficient and not have to worry about running a generator much anymore. Sounds like you have your solar setup done pretty good.
Wow! You had to jump into getting powered up with hardly any time to learn what to do or gradually afford components! Sounds just a bit stressful. I was a little more fortunate. Like you at first, I was initially set up someplace where I had power connections but I knew it couldnt be permanent so I began researching and buying solar components as i could afford them right from the start. Then, a couple years ago, I built a garage for my RV on some property I own up here in northern Maine. I installed the few panels Id collected by that point onto the roof of the garage and controllers and batteries in the basement of the RV. Then I just kept expanding the system as i could afford to. I connected my garage to the grid when I 1st built it and moved my RV into it but Ive reached a point in the expansion of my solar set up that I no longer need the grid and simply keep the breakers off. I still get a bill from the power company though. Up here, we have to pay like a $20/month "connection fee" whether we use any power or not!
By the way, I started out with everything at 12v as well. After I collected enough panels to make it worthwhile, I converted the solar side of my set up to 24v since it helped with wiring costs and so forth. I kept my battery bank 12v though, figuring that was more sensible since my RV and most of its appliances were all 12v. To include my TVs, modem, router, lights(which Ive converted to all LED) and so on. I thought about converting my battery storage to 24v or higher but am not sure how I would benefit from that. And Id also have to buy and install a 24v to 12v converter in order to keep using all my 12v stuff. Anyway, it sounds like what your doing is as much fun for you as a necessity. Thats how it is for me as well. Id rather spend my money on playing with my power set up than fancy toys or going out to eat. I consider the whole thing as much of a hobby as it is a lifestyle.
vbadov
New Member
Thanks for the reply to the original comment. It helped me a little I've got to do a lot more grounding research because I don't know anything about it. I have my system I think I made a comment earlier on this post about what kind of system I have. I don't have anything grounded n you've grounded all your stuff.
Ground is so foreign to my brain. I guess I better do some studying if I'm going to put in my new system also a 48 volt system in my work trailer garage
I keep repeating that Im no expert because I dont want anyone to take my advise as gospel. Id rather they check with someone who IS an expert. Having said that, I do think that logic and common sense can help solve many an issue. Grounding, for example; My RVs main power cable is a heavy duty 3 wire cable(the 3rd wire is connected to the "ground" prong on the plug). On the RV side of that cable, the pos and neg wire connect to the RVs 110v breaker box which feeds all of the RVs 110v power needs. Everything that gets powered through the RVs 110v breaker box is also supposed to have any communicating conductive surface connected in some way to that 3rd ground wire in the power cable. So if say, the live wire providing juice to my AC comes into contact with the metal junction box that cotains it, a junction box that is also connected to that 3rd ground wire of the main power cable, most of the wayward current will be diverted down that ground wire, out through the third prong of the plug end of the cable, and the safely into the ground through the ground rod configured into the 110v meter/breaker box of my garage. If that ground wire didnt exist, the wayward current caused by the short would seek ground through some other route which would most likely be me if i touched the junction box. The ground wire simply provides a far less restrictive path to ground than my flesh does.
I dont have much doubt about what I just said but here comes the part that I dont know 100% for sure but Im thinking makes "common sense". I know that all of my RVs internal, 12v wiring is grounded to the chasis. Im pretty sure that the ground wire from my RVs main power cable is also connected to the RV chasis. Therefore, any short of any type would escape the RV through the main power cables ground wire.
Thinking about all this has made me realize a potential problem with my own set up! Instead of having my RVs main power cable plugged into an external, grounded outlet, I have it plugged into an inverter that is bolted down in the basement of my RV. This means that I havent really got anything grounded at all!! The way Ive set things up, I need to connecr the RV chasis to ground to make my system safe. Hey! So thanks for getting me to think about it more! And after this, i definitely suggest you research things for yourself and not listen too much to non-experts on the net lol
12VoltInstalls
life passes by too quickly to not live in freedom
What does this mean? You changed from parallel single panels to 2S?
this is wrong in several places
you mentioned logic but your logic isn’t based on science.
The actual ’wayward current’ through the bare/green/earth ground will trip a breaker if installed correctly. THAT is how it protects you.
I would suggest ALSO installing a GFCI breaker in the panel for a main breaker. That is a measure of protection as well.
I don’t know of a 30A GFCI outlet so for a 30A RV cord you need to use a breaker.
Sorta but not. GFCI stops the current from killing you.
It won’t escape or shut off but the breaker would disconnect a short.
Again GFCI will interrupt the circuit before electricity can kill you, the breaker detects a short. ‘Escaping’ voltage that is enough to kill you can exist without tripping a breaker.
I suggest going to the ‘resources’ and studying the several postings on grounds and safety.
And while you are there in resources also study the instruction paper on bonding and grounding. If not connected via shorepower your system may not be grounded at all, and there are important considerations to what is called “neutral to ground bonding”
?
To get corrected on any faulty assumptions I may make is a big reason that I post in here. It helps me learn. Especially when the person who corrects me is so pleasant and tactful! So thanks for the info. And that I know Im guilty of making faulty assumptions sometimes is exactly why I preface any advice I may try to give with a healthy dose of, "I am not even close to being an expert on this but..." and then ultimately advise folk to seek out an expert.
Anyway, yes! I took pairs of12v single panels and connected them in series. Is that important?
Also, I hired an electrician to wire up the important parts of my garage, to include the RV electrical hook up but as I said, I dont connect my RV to grid very often anymore. And the electrical internals of the RV are the same as they were from the factory. In fact, when I think about it, all Ive done is install a solar charging station in the basement of the RV and connected the 12v battery bank of that station in place of the two smaller capacity house batteries that came with the RV. Finally, I attached an inverter to the battery bank and plugged my RV into the inverter. Not terribly complicated, really. Of course Ive used proper gauge wiring(i always err on the side of caution when it comes to that) and have everything run through the appropriate breakers.
So despite all my faulty assumptions, it seems as if my set up is fine except for the fact that nothing about my electrical supply is grounded at the moment lol! Thats a pretty big fault but as you saw from my previous musings, its a fault that I had already discovered on my own. Which is another reason I took up with this forum and write long posts. A lot of times, doing so helps me figure something out on my own.
Anyway, yes! I took pairs of12v single panels and connected them in series. Is that important?
Also, I hired an electrician to wire up the important parts of my garage, to include the RV electrical hook up but as I said, I dont connect my RV to grid very often anymore. And the electrical internals of the RV are the same as they were from the factory. In fact, when I think about it, all Ive done is install a solar charging station in the basement of the RV and connected the 12v battery bank of that station in place of the two smaller capacity house batteries that came with the RV. Finally, I attached an inverter to the battery bank and plugged my RV into the inverter. Not terribly complicated, really. Of course Ive used proper gauge wiring(i always err on the side of caution when it comes to that) and have everything run through the appropriate breakers.
So despite all my faulty assumptions, it seems as if my set up is fine except for the fact that nothing about my electrical supply is grounded at the moment lol! Thats a pretty big fault but as you saw from my previous musings, its a fault that I had already discovered on my own. Which is another reason I took up with this forum and write long posts. A lot of times, doing so helps me figure something out on my own.
12VoltInstalls
life passes by too quickly to not live in freedom
Thank you for that. I mean no harm but sometimes the receiver infers ill intent.
I’m no expert either. Don’t mean to come off that way. I do try to know enough to know what I don’t know…
easily remedied.
Since plugging in a cord is your “transfer switch” you can probably bond at your inverter because as soon as you unplug the RV cord from the inverter duplicate N-G bonding becomes impossible. If, however, you change to an AIO or some other inverter/charger arrangement where grid could be connected at the same time the inverter power is connected you will have to address that differently.
I would at least do the N-G bonding asap and swap the rv breaker panel main breaker with a GFCI.
The info you just posted made me think of something else concerning the grounding of my set up. I said I wasnt connected to the grid anymore, but thats not technically true. I use an generator auto switch. Going into it is power from my inverter and power from the grid. Coming out if it is a heavy cable that feeds a 30amp outlet that I plug my RV into. I have it set up to auto flip from inverter to grid when the switch senses no power from the inverter. It auto flips back when the switch detects inverter power again. I mention this because that set up shares a common ground back into my breaker box. Which means that my RV electrical is grounded, apparently. But maybe Im missing something?
I generally seek a lot of information before taking on a project I dont know a lot about. Then I do the project and, because i dont do the same project every day, or for a living, i let go of a bunch of what I learned to the point that I sometimes forget what Ive actually done! This is one of those cases. The cable that plugs into my inverter and goes to the transfer switch looks exactly like the cable that comes out of my RV and normally plugs into shore power. So I somehow started thinking the RV was connected directly to the inverter. Forgot about the switch intermediary entirely for the purposes of this discussion on grounding.
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12VoltInstalls
life passes by too quickly to not live in freedom
Maybe. If the shorepower is connected constantly to the xfer switch the N-G bond exists in the entrance panel that feeds the outlet the shorepower is plugged into. Or should be. In that case, there should not be any N-G connection in the RV since it sounds like the transfer switch doesn’t disconnect the bare/green/ground.
Read the resources paper on grounding and bonding.
I dont think that the fellow I was talking to about this stuff earlier will be connected to the grid in any way at all. He says his grid power has been shut off which is why he went solar in the 1st place. So depending on where and how he installs his inverter, he may be in the same boat grounding wise as I thought I was in.
Thanks again for your information and pointing me in the right direction for more of it.
I will definitely review that paper(once i find it ?) and give my hook up a close inspection afterward.
12VoltInstalls
life passes by too quickly to not live in freedom
Thanks a TON!!!
vbadov
New Member
Thank you very much great comment. I really appreciate you
My experience is that my RV connected all grounds (AC & DC) to the frame and is all connected to the utility ground when connected to utility power. Two ground rods are discouraged as far as I read.
Also look here: https://forums.mikeholt.com/forums/bonding-and-grounding.22/
Also look here: https://forums.mikeholt.com/forums/bonding-and-grounding.22/
