Neutral and ground bonding on inverter inside caravan

[Scph9002]

Hi. I want to apology in advance for convoluted text ahead, TLDR further below, but I don't know how to explain it more neatly and it is regarding something a certified electrician should do not an average Joe. I'm aware of the fire hazards and personal hazard of high voltage

Can I bond neutral and ground inside an Epever inverter? I used to have neutral and ground bonded in my caravans service panel and that worked great when I ran my caravans 230volt system from the inverter. I was able to trip the ground fault device or RCD by trying to run appliances from ground and line but...
when i disconnected my inverter and connected household ac to my caravan fuses in my house popped. What happend was my house neutral and ground are also bonded and I had a 50/50 shot of plugging in mains ac outlet the right way up (europen ac plug)... basically what happened was mains line and neutral shorted via ground lol. If i plug the ac outlet in upside down that means ground is bonded to neutral in house panel and in caravan panel ground is bonded to line. Costed me 3 fuses before i realized wtf was going on

Therefor since i use 2 different sources of 230v, inverter and main house hold I cant bond neutral to ground in my caravans service panel. That introduced another issue.. I cant get my RCD to trip running off my inverter anymore. RCD tripping works fine when running of house holds ac though.

I have made sure it is impossible for my inverters ac out and any household ac out to be connected at same time to my caravans ac in. My caravans AC in is a plug I have to choose to plug in EITHER to inverter or to a house hold ac out. Idiot proof =)

TLDR
I can safely bond neutral to ground inside the Epever inverter right? Also.. it doesnt matter if i bond "neutral" or "line" to ground inside inverter right? I mean both are the same and whatever I choose to bond to ground is going to be called "neutral" from then on?
TLDR END

On a side note..not sure what significance it has with anything but as the inverter is now unbonded with floating ground..the potential between ground and first line is around 65v and the potential between other line and ground is around 165v. Would it make a difference if i bond the lower or higher voltage to ground making it the neutral?

 

[FilterGuy]

It is frustrating to me how poor so many inverter manufacturers are about the grounding scheme documentation.
. I looked at a couple of EPEver manuals and did not see adequate documentation. Could you post the exact model of your inverter (or a link to the manual). Maybe I was not looking at the correct one.


Meanwhile, have you tried contacting EPever about this?

when i disconnected my inverter and connected household ac to my caravan fuses in my house popped. What happend was my house neutral and ground are also bonded and I had a 50/50 shot of plugging in mains ac outlet the right way up (europen ac plug)... basically what happened was mains line and neutral shorted via ground lol. If i plug the ac outlet in upside down that means ground is bonded to neutral in house panel and in caravan panel ground is bonded to line. Costed me 3 fuses before i realized wtf was going on

It sounds like you are using a non-grounded plug. I have no idea what plug standard you are using, but I believe all of the European standards have grounded and therefore polarized versions of the plugs. Wouldn't that eliminate the problem of plugging it in backward?

However, even with a grounded plug, if there is an N-G bond in the camper you run the risk of two NG bonds and that will cause current on the ground wire. (It will probably trip any RCD breakers in the circuit)

That introduced another issue.. I cant get my RCD to trip running off my inverter anymore. RCD tripping works fine when running of house holds ac though.

If I am following the description correctly, when plugged into the house power there are two scenarios:

1) Plugged into house power and running off house power..... RCDs work correctly
2) Plugged into house power and running off Inverter.... RCDs don't work correctly.

That says the inverter is isolating neutral when running off of the inverter but passing neutral through when running off of house power.

Assuming I am correct with the above, it tells me that there needs to be a dynamic N-G bond and the inverter is not providing it.

There is a similar problem with Growatt inverters and after much research, this turned out to be the best solution:




What we don't know is if it is OK to jumper the AC-In neutral and AC-Out neutral on the EPEver inverter. (And I don't know how to find out)

I have tried to figure out a circuit that would do the dynamic bonding but not require the jumper of AC-In neutral and AC-Out neutral. Unfortunately, every circuit I come up with has problems during the transition between local and grid N-G bond. (The circuits briefly create 2 N-G bonds when transitioning between Inverter power and grid power. The brief moment of both will trip a GFCI and probably trip a European RCD.

 

[Scph9002]

The epever inverter is just a basic offgrid inverter. No AC in. Only AC out so it must not be connected to caravan at same time as house ac. I have made sure of that. I must manually plug in caravans ac plug into either inverter or a an extension cord from house.

Anyway I just soldered a wire between one leg and ground inside the inverter. Testing continuity with multi meter between line and ground on any ac outlet inside the caravan when running of the inverter will now trip my RCD and break power so I guess all is good? Im not sure what the proper way to test RCD functionality is

 

[SolarGarden]

It is frustrating to me how poor so many inverter manufacturers are about the grounding scheme documentation.
. I looked at a couple of EPEver manuals and did not see adequate documentation. Could you post the exact model of your inverter (or a link to the manual). Maybe I was not looking at the correct one.


Meanwhile, have you tried contacting EPever about this?


It sounds like you are using a non-grounded plug. I have no idea what plug standard you are using, but I believe all of the European standards have grounded and therefore polarized versions of the plugs. Wouldn't that eliminate the problem of plugging it in backward?

However, even with a grounded plug, if there is an N-G bond in the camper you run the risk of two NG bonds and that will cause current on the ground wire. (It will probably trip any RCD breakers in the circuit)


If I am following the description correctly, when plugged into the house power there are two scenarios:

1) Plugged into house power and running off house power..... RCDs work correctly
2) Plugged into house power and running off Inverter.... RCDs don't work correctly.

That says the inverter is isolating neutral when running off of the inverter but passing neutral through when running off of house power.

Assuming I am correct with the above, it tells me that there needs to be a dynamic N-G bond and the inverter is not providing it.

There is a similar problem with Growatt inverters and after much research, this turned out to be the best solution:

View attachment 74172


What we don't know is if it is OK to jumper the AC-In neutral and AC-Out neutral on the EPEver inverter. (And I don't know how to find out)

I have tried to figure out a circuit that would do the dynamic bonding but not require the jumper of AC-In neutral and AC-Out neutral. Unfortunately, every circuit I come up with has problems during the transition between local and grid N-G bond. (The circuits briefly create 2 N-G bonds when transitioning between Inverter power and grid power. The brief moment of both will trip a GFCI and probably trip a European RCD.

I haven't tried it, but what do you think about this with a double pole double throw relay? One thing though, my inverter does not click in the AC from the grid for a full five seconds after it is on, which would mean that the output would be on inverter power without an earth for this time. Would that matter?