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Old 05-12-2021, 03:00 AM   #1
Mini-Skoolie
 
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Question Inverter Ground Fault

Good day,
I respectfully request your expertise.

So here is the scenario:
Renogy 2000W inverter
Renogy 100w solar x2
Interstate batteries x2 (I have not been able to sort out Amp hours yet...but willing to take advice. They are not the final solution, but they are what I have now.)
Solar works, Batteries charge and discharge, inverter runs shop vac, chop saw, heavy duty blower...with an extension cord (so I don't think it's the inverter...maybe).

When I use a generator to the circuit breaker box, all outlets in the bus work (120v).

When I plug the circuit breaker box into the inverter, all I get is a ground fault (light and unit shuts down).

All outlets test correct when using the plug-in outlet tester (similar to this one)
I've tried using the separate grounding screw on the inverter to the circuit breaker box, to the 12v fuse block, to the common ground (bus chassis) for the batteries (all three, two of the three, and each individually). I've used different wire gauges 12, 10, 6 and 4. (Only the extra ground. Not the main ground, which is 2.)

I can plug in the circuit breaker box, flip one circuit (#2)(the only one with 1 outlet) and no problems until I plug in something to the outlet (a power strip with nothing else plugged in...so I can see the light and have a switch to turn on/off to test. Only fails when power strip is turned on).

If I flip any of the other circuits, I get a GF error.
One circuit (#1 - 4 outlets, no load) has GFCI outlets (2) (yes, I know, I only needed one, but I had it and it worked.)
The second circuit (#3- 3 outlets, no load) none are GFCI.

I swapped circuit breakers in the box (moved to another position in the box) with no noticeable differences...so I switched them back so my diagram is correct.

I've talked(been on hold) with Renogy, and I've received hours (5+) of waiting, talking, then being put on hold, disconnected, and/or getting the "I dunno, just send it in."(but never further instructions from customer service).

Oh...and I used red, black, and white wires...but that surely has no effect, right?

ANY suggestions or recommendations to check/inspect/solve?

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Old 05-12-2021, 09:11 AM   #2
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For giggles... with power off for obvious reasons, go to the final outlet in each circuit and check for continuity from each wire (hot, neutral, and ground) to chassis ground.


The inverter's gfci system may be more sensitive than that of the generator.


Also, make sure your gfci outlets are wired correctly (they have a line and load size).
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Old 05-12-2021, 10:06 AM   #3
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Are neutral and ground bound together in the circuit breaker panel?
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Old 05-12-2021, 10:17 AM   #4
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Or in genny?
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Old 05-12-2021, 10:42 AM   #5
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There was another thread here where the op questioned whether a breaker panel should even be used with an inverter bc of this issue. Generator bonding and inverter grounding were discussed.

Your Renogy inverter is bonded. I have a similar situation which I think I have solved but I won’t hijack your thread.

Peace
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Old 05-12-2021, 10:51 AM   #6
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Quote:
Originally Posted by Meathead View Post
There was another thread here where the op questioned whether a breaker panel should even be used with an inverter bc of this issue. Generator bonding and inverter grounding were discussed.
Sounds like your experience might be the most valuable to the OP.


The reason I ask about ground/neutral bonding in the panel- My understanding that that AC breaker panels in a bus/mobile application should always be wired like sub panels, not like mains- it is the job of the upstream source energizing the panel to bond neutral and ground as appropriate... which is also part of the reason why I think people should have hardwired inline surge/wiring protector devices just downstream of their 30A/50A RV inlet.



AC ground to chassis is an entirely different conversation.
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Old 05-13-2021, 10:01 AM   #7
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There has been a lot of discussion on this subject. Below are a few. I will not offer my opinion as I am not qualified.

Peace

https://www.skoolie.net/forums/f49/e...ice-27171.html

https://www.skoolie.net/forums/f10/n...ing-27366.html
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Old 05-16-2021, 11:14 AM   #8
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Thank you all for the feedback. As someone mentioned in one of the connecting posts, this is a potentially confusing subject. It's been a crazy week, and I am going to attack some projects on the bus today.

I got the bus with the 120v electrical completed because I know the basics about wiring, but not the specifics. I was told "Just add the inverter". Seems like that isn't exactly true.

So, before I jump in and change anything, let me add more information that it sounds like would be helpful.

Bus Wall

Bus Panel

Gray wire wiring


The inverter is currently in the space in the upper right on the "bus wall" photo where the wires were left unconnected.
Power comes to the bus through the outlet on the wall (middle of the wall, black rectangle in the image) when I am using the generator. I use the gray plug (top of the image) either in the inverter or the wall outlet. I even checked the connections on the wire to make sure they were consistent. I am the transfer switch, and will move the plug between the inverter or the outlet.

While I have now learned about bonding, generator vs solar vs land line (now I have research more about 30a/50a setups too), I have not yet understood how to change from bonded to not bonded when switching between generator and solar.

I am also concerned that I need to add more protection against surges before the box, but only for land/generator?

Thanks again. I can't tell you how much this is appreciated. I have tried to reach out locally, craigslist, and "call a friend", but this group BY FAR has been the best at actually knowing. I've had two "experts" look at the bus and both have said they can't find what I need. I REALLY don't want to burn up all my hard work...oh, and my family too.
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Old 05-16-2021, 12:43 PM   #9
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Disclaimer, I am not an electrician.

Quote:
Originally Posted by AdamKnox View Post
You are bonding in the panel (ground and neutral go to the same bar) which is not recommended and I think may be the source of your inverter problem. The bus panel should be wired as a subpanel- do not bond neutral and ground here.

A simple test for your issue:
  1. Disconnect the inverter from the panel and ensure the panel is not energized.
  2. Remove the grounds from the neutral bar, and combine all circuit grounds with the (red) ground wire but separately from the neutral bar.
  3. Do a continuity check between neutral and ground to ensure there is no link
  4. If there is no continuity between ground and neutral, connect the inverter.
  5. Retest your inverter problem and let us know if it persists.
Either way, problem persisting or not, like mentioned do not bond ground/neutral in the panel here. It is not a mains, it is a subpanel. If this resolves your problem, do a continuity check between ground/neutral with the inverter connected to see if the inverter itself makes this bond, which I suspect may be the case.


Your main panel has a pair of raised screw holes at the bottom right so that you can optionally install a ground bar for the ground connections- use it.

Quote:
Originally Posted by AdamKnox View Post
I have not yet understood how to change from bonded to not bonded when switching between generator and solar.
As stated, your inverter may already have this bond. Some generators already have this bond. You would have to test these pieces of equipment to make sure one way or another. If they don't, you can do this bond at a changeover or transfer switch.

If you install an RV service inlet 30A/50A, you are going to need to redo some things. Electricity is dangerous one way or another but if you are thinking of shore power you really need that panel up to code for a residential sub panel because now you are dealing with grid power. You can't get away with some of the things you've done here to get inverter power (bridging each phase inside the panel, serving the panel with a 3-prong house plug, etc).

Like I mentioned in the previous post... I suggest installing a hardwired surge protection device just downstream of any RV service inlet:

30A
https://www.amazon.com/PROGRESSIVE-I.../dp/B002UC6RSA
50A
https://www.amazon.com/PROGRESSIVE-I.../dp/B003AN1UA8

Many of these catch wiring problems at the pedestal like open neutral/open ground problems that you may not notice immediately otherwise, and can cause damage to your rig.
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Old 05-16-2021, 08:50 PM   #10
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Well, it is all good now.
I "unbound" the ground and common, rewired them separately (isolated) from each other, and WOW! It all works now.

Thank you Kazetsukai and Meathead!

NEW Electrical box

Next time, I will test the Generator with the system.
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