Does GE AIO + Gateway need earth rod?

Hi can I check whether I need earth road installed for the AIO + Gateway? My understanding is that it will need a seperate earth rod especially if using in island mode or full disconnection from grid? I might be completely wrong.

Installer has told me I don't need a seperate earth rod as isolation is handled by the inverter which is also givenergy 6kw inverter.

Whole house has been rewired and the consumer unit is a PME TNCS system.

If anyone can help confirm I would grateful. In the mean time I have asked the installer to put in writing that no additional earth is required in writing.

Bal forgot to mention I have 16x 405 solar panels on the roof too

Bal
See the installation manual here - https://kb.givenergy.cloud/article.php?id=85&oid=1

In particular -

An earth rod did not used to be mandatory according to the manual (mine wasn't when it was installed last Sep). It is now. And mine had to have one retro-fitted.

I am not an electrician, but, my understanding is that if the system goes into Island Mode, then I think that means that the whole connection to the grid has gone - and that includes an earthing point. Then in that set-up the system needs an earth reference (and hence the rod). As I say I am most definately not an electrician, but that is my understanding

CW I too am not an electrician, but totally agree that a separate earthing rod is needed. I have a 13.5 kWh AIO plus GW and had an earth rod installed

Yes because if you have a power cut caused by a broken cable in the road then you might not have an earth connection from the substation which would be dangerous in your house. Metal cased objects that are earthed would tend to float at half the mains voltage due to all the mains filters in modern appliances. If there was a faulty device they could become fully live.

Mine is in the same cupboard as consumer unit, installed last July but I don't believe I had one installed, we have already had a power cut and everything seemed fine though.

Jellybaby
You may want to have a read of this thread - https://community.givenergy.cloud/d/4921-force-off-grid-toggle

It includes a link to this post - https://community.givenergy.cloud/d/4342-whole-house-backup/47 and, I think, a beginners explanation of why one is needed.

As I mentioned, v1 of the install manual (dated June 2023) did not require an earth rod. The mandatory requirement was introduced in v2, which I believe came out in Sep 2023. I have copies of both.

My Gateway was replaced a couple of months ago. As part of that process I had an earth rod installed (near my meter, not the Gateway). My installer did the replacement, but GE told him to fit an earth rod.

It sounds to me like it would be sensible for you (at the very least) to ask GE whether you should get an earth rod installed.

PianSom If there's no earth rod and island mode powers circuits in the property then the install is non-compliant with wiring regs. This is all caused by GE/Chinese designers of the AIO not understanding the regs and was discussed in various threads here ("IT mode earthing").

With an elegant inevitability that will also invalidate any buildings and contents insurance should anything go amiss.

I'd get it sorted were I him.

What people don’t understand is there are only two wires that come from the grid. If the grid goes down then there should be no power coming from your house back to the grid (especially if there are people working to get it going again. The GW stops any power going back to the grid therefore an earthing rode is required.

In the UK, only two wires — live (line) and neutral — typically come into the house from the utility grid. However, this system is part of what’s known as the TN-C-S (PME - Protective Multiple Earthing) earthing arrangement, which is common in the UK.

Here’s a breakdown of how it works:

TN-C-S (PME) System:

Live (Line): Carries the incoming electrical supply’s voltage (typically 230V in the UK).

Neutral: Returns the current to the grid and is also connected to earth (ground) at multiple points, including the substation and at the point of entry to the house.

In this system, while only live and neutral are physically supplied by the utility, the neutral is earthed (grounded) both at the substation and at the property. This connection allows the earth connection in your home to be made locally, using the same point where the neutral enters the house. This is why, even though only live and neutral come into the property, there is an effective earth connection available at the consumer unit (fuse box).

Earthing in the Home:

Inside your home, you will have a separate earth (ground) wire connected to metal parts of your electrical system and appliances. This earth wire is connected to the neutral at the main consumer unit, providing a safe path for fault currents.

In summary:

Only live and neutral enter the house, but the neutral is earthed at the point of supply, creating an earthing system for safety.

The house has an earth wire within the internal wiring, even though it doesn’t come directly from the grid but is bonded to the neutral at the supply point.

Daveb01 Great explanation - whilst I understood the TN-C-S, I could never understand why the earth in the house was connected to the neutral...... now I do 😃

How did the first AIO initially get away without an earth rod when the gen 1-3's all required them for EPS?

Hook None of the installers tested trip circuits in island mode.

Edit - or if they did then GE fed them BS when they queried it. Have a search around on here about "split-phase" etc. @hoggy worked it out as usual....

Edit2 - IT earthed is basically no N-E bonding. That's what the AIO's (gateway) were all like up until some date last year.

My installer is coming back tomorrow to (hopefully) fit a larger breaker (possibly 100mA) which I understand from reading on this board will likely sort the problem out.

Without being an electrician, from the behaviour I have seen (AIO breaker tripping on outage, AIO breaker not tripping but taking 30s to cut-over on outage and whole system behaving as you would expect) I thing the earth leakage posit is likely correct - time will tell.

My main CU has RCBO's (30mA) on all circuits so there is no danger there of having a larger break at the Gateway I think

Just to get back on topic, I have earth rod being installed. There was just some miscommunication between office staff and actual installers.

Daveb01 In this system, while only live and neutral are physically supplied by the utility, the neutral is earthed (grounded) both at the substation and at the property.

I hadn't heard of the neutral being grounded at the property - surely if that was something you could rely on, then there wouldn't be any need for a local earth rod.

DD Neither TNC or TNC-S are grounded locally at the property (in the UK).

DD

Also in simple terms (normal operation) your relying on earth from the grid and as it enters the house or back at the sub station etc. During an outage the GW cuts off that route so no electric can get back to the grid and no effective earth. The earthing rod would then take over this function.

Because people see an earth cable in sockets & the CU they automatically think the house has an earth where in fact it’s going back to the Grid.

Daveb01 Returns the current to the grid and is also connected to earth (ground) at multiple points, including the substation and at the point of entry to the house.

What's all that about then? Its not earthed at the point of entry.

Daveb01 During an outage the GW cuts off that route so no electric can get back to the grid and no effective earth. The earthing rod would then take over this function.

this is not specific to the GE gateway... There's a lot of fuss about 'PEN fault protection' in EV chargepoints - the neutral cable can break a long way from your house (eg roadworks on the next street) and you lose earth protection.

If the neutral was grounded at entrance to each property, this would not be a problem.

DD This may be the wrong way of thinking but if neutral was joined to earth both at the substation and the premises and the neutral broke in the street then the neutral current would try to find its way back to the substation through the ground. This is likely a higher impedance so you would have lots of different ground potentials between premises and the substation. I don't like the sound of this so I wonder if the neutral shouldn't be bonded to earth at the premises but only at the substation/transformer?

Windy Miller This may be the wrong way of thinking but if neutral was joined to earth both at the substation and the premises and the neutral broke in the street then the neutral current would try to find its way back to the substation through the ground

The problem is because the neutral is not grounded at the premises. As you say, if the combined neutral/earth cable breaks out on the street, then your house appears to continue to be powered, but the current is having to find its way back to the substation via any ground path it can.

And RCDs don't help because there's no mismatch between out/return on individual circults.

If you search for "PEN fault" there's quite a lot of coverage in car charging stuff. It only really comes up when looking at high-powered devices running outside, where there's risk of the user being in contact with a real ground connection. Hot tubs are another case. Indoors, metal surfaces are bonded so that, while they may be at high voltage relatve to ground, they're the same as the case of any metal appliance.

I think it’s quite difficult to understand, however to get back to the question in this post, I would say yes it is compulsory to have an Earthing Rod if you have a Gateway or any EPS function in the house. (If you don’t have one get one fitted asap)

If you have RCD’s & RCBO’s (AC) instead of RCBO’s (A) you may still get the switches tripping. I now have all RCBO’s (A) and test the EPS function every quarter and don’t have any issues.

Windy Miller I don't like the sound of this so I wonder if the neutral shouldn't be bonded to earth at the premises but only at the substation/transformer?

Assuming you're talking about island mode then grid neutral isn't bonded to earth at the premises when grid power is available. Its only bonded locally (via a relay) on loss of grid power. Basically 3 relays will toggle on loss of grid power - N & L will be disconnected from the grid and a few milliseconds later the local neutral will be connected to the local earth.

If not then you're talking about TT earthing and the problem with this arrangement is calculating Zs as it'll include the generating equipment, supply network, supply transformer and so on. It is a monumental PITA and to be frank I doubt the average sparky would be capable of doing it.

Vestas Sorry I was ambiguous. Actually I was just talking about the fault scenario that was in the previous message where the house feed cable had a broken neutral outside of the premises. Nothing to do with the AIO which I do understand needs to enable a neutral/earth link after it disconnects from the incoming house feed.

House is always earthed at the premises to ground by whatever means (Earth Rods, water pipes! or other earth bonding).

If neutral is also joined to ground at the premises then, when the particular fault occurs of losing the neutral in the road, the ground becomes the current return path back to the substation. The house is still powered so the owner may not realise anything is wrong (or perhaps finds symptoms of low voltage). But ground now has a potential depending on the return current and the ground impedance. This I didn't like the sound of.

If neutral is only grounded at the substation and not at the premises then when this particular fault occurs the house goes off. Its neutral will probably be sitting at live potential. This would be my preferred failure mode for this type of fault so were suggesting that joining neutral to ground at the premises and substation was not as good as joining only at the substation.

(When something fails I'm always careful of possible shocks from either live or neutral conductors and check with my meter first.)

Daveb01 If you have RCD’s & RCBO’s (AC) instead of RCBO’s (A) you may still get the switches tripping. I now have all RCBO’s (A) and test the EPS function every quarter and don’t have any issues.

Slightly off the topic of earth spikes, I have the EPS circuit of my hybrid inverter wired up to the original house fusebox (no high load appliances, the kitchen, showers, oven etc are all on a separate fusebox when the house was extended).

The fusebox has just simple breaker switches, type B I believe, not RCBO’s. The whole lot is protected by a single 25A 30mA RCD, a Newley NLRCD2530A (this one https://amzn.eu/d/iOkIZLH).

I get occasional trips from the RCD which is quite annoying as they happen at random often months apart. I could understand it maybe if the RCD went when a bulb blew, but there’s no pattern.

The GivEnergy installation manual only says it needs a 25A 30mA RCD, says nothing more. Is my RCD the wrong type or if I replace the type B breakers replaced with type A RCBO’s will it stop the tripping?
Looking at my much newer extension fusebox, it has RCBO’s and RCD’s, but no marking on any of them as to what type they are.

Would be good to get this resolved.

geoffreycoan

I have these in my CU pic 1
This is the meaning of curve B pic 2
Info sheet
https://www.farnell.com/datasheets/2672190.pdf

Think I may have confused people as I also have EBB RCBO type A in my GW (sorry)

Residual current devices are classified as Type AC, Type A and Type B and operate as follows:

Type AC. Ensures tripping for residual a.c. currents,

RCBO in my GW are now type A x 4 (they were AC) for PV in and 1 x AIO.

Type A Ensures tripping for residual a.c. currents and pulsating d.c. currents,

Type B Ensures tripping for residual a.c. currents, pulsating d.c. currents and smooth d.c. currents.

Figure 1 shows the symbols used for the different types of RCD which can be found on the front of the device.

PianSom I sent them an E-Mail about it, just gota reply and they are saying its always been required.

Jellybaby They're being economical with the truth 😉

Jellybaby
My installer gave me a doc pack at the handover. The version of the AIO manual in that did not have the requirement.

In any case, you now know that one is needed. Good luck with sorting it out. Let us know how you get on.

Here is the copy of my AIO document v1.0 (I had mine installed 17 August 2023.
It does not have any mention about an earthing rod as mentioned above, however my installer said I would need one as all EPS systems need an earthing rod.

https://midsummerwholesale.co.uk/pdfs/all-in-one-installation-manual--june-2023-.pdf

My installer has just said the UK code for installing an earthing rod was published in 2018. Initially for EVC’s.

He sent me this, and said it’s in the regs for an electrician and if GE did not say it in there docs it’s the installers responsibility. Hhhmmm glad mine did it anyway.

The independent output is not permitted to rely on the distributor's means of earthing in the UK - this is covered in BS 7671 (Regulation 551.4.3.2.1). You will need a consumer earth electrode, but this can be connected to the MET.

The IET Code of Practice for Electrical Energy Storage Systems recommends such a “backup supply" operates in TN-S in island mode. Again, requirements for transfer of supply and switching means of earthing must comply with a number of specific Regulations in BS 7671.

... and there's the answer to the original question! 🙂

@Bal

PianSom Excerpt in screenshot but read all about it in the link below.

https://electrical.theiet.org/wiring-matters/years/2021/84-march-2021/island-mode-earthing-arrangements-new-guidance-in-the-second-edition-of-the-iet-code-of-practice-on-electrical-energy-storage-systems/

My first AIO installed last November, they fitted an earth rod.

When I had the second AIO fitted the RCD that came in the gateway was swapped out for 2 type A RCBO’s, one for each AIO.

I have the 0 second EPS setting enabled and when I cut the grid power the switchover and back is seamless and nothing trips. The lights don’t even flicker.

JasonF Mine nearly does that! I too have an earth rod installed fairly near the gateway. It currently switches seamlessly over to backup, and then about 10 seconds later the AIO breaker in the gateway trips. Currently being investigated by GE