EPS wiring question - re earth

hi folks,

have a question on wiring earth to eps circuit. I have a socket wired from the eps on the inverter. From the inverter to a 10amp rcbo then onto the socket. When i say I - the electrician who wired it. He ran an earth from the rcbo to the house earth which runs to an earth rod (ireland). Thats what the givenergy installer recommended. My question is - why do you need to earth the eps circuit again? Would the inverter not be earthed? and provide earth to the eps? Is there a reason why the additional earth is required? im wondering have i a 'double earth' situation going on. If thats even a thing. I have occasional rcbo tripping on the inverter power supply and curious if this could be causing it.

Kind Regards,
Michael

michaelmcgoldrick usually the EPS needs earthing as when the grid is down, there's no grid earth

Having your own earth rod solves that problem.

When in normal operation, the EPS will be fed from the grid, thus using your earth rod.

When in a power cut situation, the inverter is cut off from the mains and thus the EPS circuit needs an earth - it cannot physically connect to the earth rod or grid earth via the mains cable out of the inverter (as it's disconnected).

As for how it's wired up, that's a question I can't answer (not an electrician). Maybe it needs it's own earth rod. Not sure on regulations, especially for Ireland!

TX200 in a power cut though - i understand the mains is cut off - but would there not be a path for the earth back from the inverter to the consumer board, back to the earth rod? the wire circuit is still physically intact? i wonder is the additional earth a requirement where there is no earth rod present in the house and you are earthing back to the 'dno' (uk standard)

michaelmcgoldrick no, as the inverter cuts itself off from the consumer unit.

Only the battery is connected to the EPS at that time.

michaelmcgoldrick certainly in the UK if the house has no earth rod you need an earth on the EPS as you can't rely on grid earth in a power cut.

The type of earthing arrangement varies, think there's a kB about it on their kB site. Probably in the EPS kB.

hmm ok so you definitely need the second earth then... but it should only operate in a power cut?

im not doing any of this myself.. but im wondering should there be something like a relay thats on the earth to the eps socket that it only is available during a power cut? im assuming you could wire it off a nearby socket or something that would normally be live but goes dead in the event of a mains power cut

This is where I have to bow out and hope a qualified electrician pops into this thread! 😀

I'd guess if it's the same earth it shouldn't matter, but who knows.

spoke to my electrician and we figure we don't need the earth from the inverter eps to the rcbo at all.. there's a dedicated earth to the rcbo from the earth rod.. so no need to earth from the inverter eps to eps rcbo its overkill

michaelmcgoldrick
No. there are situations that result in a power cut that could mean your supplied earth (pme) is also missing.
on top of that there would be a potential difference in the two earths.
follow the guidance for a TT earth system on the eps.

With regard to that I am despite being a qualified electrician unsure whether the whole house should be converted to TT or just the essential CU ?

positor1 supplied earth is slightly different in Ireland to the UK... we use earth rods as standard whereas i think the uk has dno supplied earth? again not sure..

michaelmcgoldrick
there is a mixture, newer properties tend to be supplied earths.

so you dont think having a dedicated earth from the eps socket to the earth rod is enough? it also needs a path via the inverter?

the inverter and batteries must be bonded together (earthed)

not talking about the batteries here though... the eps socket

lol. yes including the eps socket. all on an earth spike with a zs reading of no greater than 200

In the GivEnergy EPS Connection manual it says the earth terminals for Grid and EPS are not linked within the inverter.

Thanks so my EPs socket is wired correctly then.. in theory I don't need the earth back from my rcbo to the EPS earth but at the same time.its not doing any harm