Error 8: Ground relay test failed on Victron Multiplus II GX

I have a MultiPlus-II 48V 5kVA GX that at some point had the “Error 8: Ground relay test failed” error. It would try 3 times to switch on and then switch the AC1 and AC2 outputs off.

The cause of the error was with a problematic outside light. This was fixed.

My MultiPlus-II 48V 5kVA GX has serial number HQ2108.

On this website:

It says the following:

"There has been a change (late 2020/early 2021) in the way the Ground relay test mechanism works. Newer units use an auxiliary contact on the ground relay, while older units measure the voltage between GND and Neutral.

The advantage of the new version is that the checking of the ground relay is immune to how the system is wired, and any possible errors in wiring on the input side and/or the output of the inverter/charger."

My questions are the following.

  1. Would the newer MP >HQ2122 handle ground relay problems differently than the older ones <HQ2122 to not cause AC1 and AC2 to be completely switched off by the MP?

  2. Do the Quattro’s handle this error differently?

  3. My installer said putting an earth leakage on the light circuit would cause that EL to trip before the MP sees the ground relay problem and therefore prevent the MP from switching off the whole AC1 and AC2 output. Would this in fact work?

In the context of the original fault (which I assume was an earth fault on a neutral wire), the test is still going to make sure that no bond exists on the output, and the result will be the same as you had in the past. The relay test will fail.

Quattro-II handles it the same. The older Quattro and Multiplus units don’t do a relay test at all and would not raise this error.

Yes I think this is accurate. An earth leakage on the output of the Multi should trip before the relay test on the Multi gets upset about a fault. Having more RCDs and the circuits split into blocks is helpful… you don’t lose everything when this happens.

Edit: I need to add a little more context here. The bonding relay test has two parts. The first part happens as part of the transfer switch test (the one that will raise error 11 if it fails), when it connects to the grid. This one checks that there is no TN bond on the output of the Multi/Quattro, and if there is, it raises error 8. The second part, is a continuous test while the inverter is islanded (the grid is disconnected), to make sure the bond is still there. This second part uses the auxiliary contact on the relay (after HQ2122), and therefore will be less “error prone”.

I presume there must be a good reason for the addition of this test?

Is there any specific drawback for not doing this test, like in the older Quattros.

Yes. The grid code requires it. Several of them, but mostly VDE-AR-N-4105 (the German one) which everyone copied. You cannot tie with the grid (ie, run ESS) unless you do the relay test.

The older Quattros cannot be legally used on our grid without the addition of the an anti-islanding device (such as the Ziehl). And in Cape Town they won’t even allow that (it is not on their list).

What I love about this relay test, is how it brings faults out in old installations. Faults that have been there for years… are found and fixed.

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Ok, thanks. I presume the Quattro2 are/will be on Cape Town’s list of allowed Grid-Tie devices?

Any idea when a higher output Quattro2 might become available?

I presume there will be a 48/10000 version of the Quattro2 at some point…

Eventually I expect the Quattro-2 to be on the list, yes. To find out when, I tell people to traverse the sales channels. They know, or at the very least they know what the hold-up is. The R & D people usually don’t :slight_smile:

So, I got the electricians in to install an EL on the light circuits to prevent the MP from detecting an EL fault and then switching off the whole AC1 and AC2 completely.

Unfortunately, these new EL’s then started tripping very often. According to the electrician this is the reason why EL’s are not normally installed on light circuits. According to him outside light circuits are very prone to a bit of dampness that then leads to tripping of EL’s.

So, I had to take the new EL’s on the light circuits out again.

If it is not needed to install EL’s on light circuits by regulation, why does the MP have to test for it? In my mind that leaves the door open for the MP to switch off the whole AC1 and AC2 perhaps unnecessarily. This will off course happen when you are away on holiday leading to freezers going off.

After all, AFAIK the Quattro does not do this test…so it can’t be mission critical.

Is there a way to disable this test or prevent the MP from switching off the AC1 and AC2 in response to detecting an EL problem on the light circuits?

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Dampness or water ingress causes earth faults in any circuit, which should trip the earth leakage. This is definitely not why lighting circuits were excused.

Once upon a time, there was no alternative to incandescent light, with its relatively high natural E/L.

Electronic circuits ( which include today’s lights) on plug circuits are not excused from E/L protection. So any argument for excusing today’s lighting is moot. The regulation just hasn’t caught up yet.

Earth leakage protection saves lives. Regardless of what outdated regulations allow, it should be deployed to cover as many domestic circuits as possible.

It is easy to blind an earth leakage, but don’t think you have solved the problem.
The worst time to remove your E/L protection is actually when you have an earth leakage fault, and you and your family members need the protection.

Tell your electrician to find the fault and to stop trying to BS you.

Thanks, Phil. Will do.

BTW, why is the MP not picking up the EL problem/s that the EL-circuitbreakers are detecting…I presume the MP is just less sensitive to EL problems?

I don’t think I understand your question correctly.
I infer from your question that you think the MP has inbuilt EL detection.
It doesn’t.
The MP’s test is to check whether the source neutral is earthed or not and to apply earth on the neutral if it isn’t. It does this because sometimes the grid is the source, and sometimes it is the source itself.
(I don’t know if it performs this test periodically or if it is just a once-off, that depends on Victron).

The power source must be earthed to be able to provide EL protection. Earthing the neutral at the source means the current can return to the source via two electrical paths, namely neutral or earth. If the source is not earthed correctly to provide a clear alternative path, it will compromise the E/L protection,
This is the test the Victron is doing. It is trying to ensure if there is E/L protection that it will work.

E/L protection, on the other hand, is a constant measure to ensure that the current that enters a circuit on Live matches the current that returns on the Neutral. The principle is that if it doesn’t match, the missing current can only be returned to the source via the earth.
Which it absolutely should not do. How is there a break in insulation to make contact with earth?

Perhaps it is your damp outside light, No.
This time it is your child fishing toast out of the toaster with a knife.
The E/L trips, and your child lives long enough to do another silly thing on another day.

Yes, that is what I thought.

I once had this error: " [Error 8: Ground relay test failed on Victron Multiplus II GX]"

It was caused by a faulty outside LED light that shorted (glass cover was black)… Once the light was replaced the error on the MP went away…

If the test that the MP does is to check that “the source neutral is earthed”…does this mean that whatever problem the light had…caused “the source neutral to become not earthed”?

Or are there other reasons for Error 8: Ground relay test failed ?

Together with this, there are grid codes that are different earthing conventions for different countries. The Victron test will be different depending on what grid code you set.
Rules like even if there is already an earth (e.g. the faulty light), “that there should not be an earth anywhere other than.”
South Africa is like this, I don’t think Australia is, but I am not clued up on that side of things.
So I don’t know the test sequence, but I figure it checks that if it is now the only power source, it should also be the only earth connection.

You have an earth fault. It needs to be found and fixed. This happens again and again. People install an inverter, and faults that have been there for years are suddenly found. Welcome to the club! :slight_smile:

So far it seems you’re trying to find a way from masking this problem from the inverter. That’s the wrong way to go about it. The right way is to find the fault and fix it.

It doesn’t, but if you have a neutral to earth fault the Multi may think that you have a TN bond on the output (which you should not have) and fail the relay test. So there is some overlap between the things that trip an RCD and the things that cause the relay test to fail. But the Multi indeed doesn’t have “full” earth leakage checking.

Some parts of the relay test is only done prior to connecting to the grid. Monitoring a constant TN bond while islanded is done periodically while inverting (that was TTT’s issue a while ago). You are quite right that an earth leakage (or RCD, which I think is a more accurate term) constantly monitors things while the Multi only checks them occasionally (once, before connecting).

He needs someone to isolate those circuits and do a insulation test between neutral and earth. One of them has a leak… :slight_smile:

This is why the Multiplus II is an approved inverter and the those older Quattro is not. The Quattro does not have the extra checks to comply with NRS 097.

Yes…will gradually proceed as close to zero faults as possible.

It is weird. Two electricians and one electrical inspector both told me that some earth leakage on the light circuits, especially outside lights, are normal!

Must say, if my sparkie tells me that, we will have an argument.

Does that mean a good check to do is that any inverter not on CoCT’s approved inverter list, probably don’t do those checks (obviously there are some pending approval)?

Those on the approved list does that check.

Those not on the list either does not do the checks, or have not applied to be approved.
The approval does cost money, but I would guess if you want to sell your inverter it is best to pay that to be on the list and as such it would be a good assumption that those not on the list would not have the features to pass the requirements. (For instance that is why only see the Voltronic InfiniSolar and you don’t see any Voltronic Axpert or clones as those don’t have what is required)

Some leakage on ANY circuit is normal, with the emphasis on “some”. If it is enough to trip an RCD, it’s too much.

The normal leakage is referred to as the standing leakage, and especially in a modern home (because of noise suppression in modern appliances and switch mode power supplies that create higher frequency leakage currents), this can be several milliampere.

The reason RCDs trip at 30mA is a bit of a compromise. It is high enough that you don’t get nuisance tripping because of the standing leakage, but low enough that it (probably) won’t kill you.

You will sometimes find, in medical establishments usually, that they fit higher sensitivity RCDs that trip at 10mA.

Long story short: Yes, some leakage is normal, but in your case the budget is completely blown :slight_smile:

It might be normal, but loadshedding is also normal, but it shouldn’t be the aim. So what happens when you bypass the RCD on the outside lights. One day someone might decide to take a spade to the ground. Close to the wire that is exposed. And then you can find out how much current prefers to pass through your body instead of the route it has been taking until now. And it is unlikely to be 30mA.

You could even just want to change a lightbulb. Who knows how easy it is to be shocked. But now “shocked” means something less benign than a quick prick and walking to the DB to reset the RCD.