We live in a complex of 12 townhouses. After a theft at our mini-sub, we have random earth leakage trips. This happens even between units connected on different phases. Up till now I could not find any problem, and even replaced the EL unit. With all the solar installations problems in here, I am thinking of disconnecting the earth connections and use a prober earth rod on my unit. Will it cause any funny problems?
Welcome Andre,
Back in 2019 got our grid tied system registered.
During the tests, the earth was problematic. Been there for donkey years. Learnt then why I could not touch a PSU of a PC on the outside standing bare feet on tiles.
Any case, Council, not their problem, as it is after the earth connection in the street box.
So electrician installed a TN-C-S earth connection.
Long copper pipe into the ground connect to DB’s earth point.
And the house earthing was sorted.
And we could register the system.
So yes, you can change it.
Just use a damn good sparkie.
Thanks, I do suspect that we have a problem with the council sub. But if using a local earth, I suppose the connection to the sub must be disconnected, and the local earth I realise would have to be good as well. I remember from my young days one outside tap that used to have a slight bite, but it did have the coldest water!
Earth leakage (Residual Current Devices or RCD) devices have no connection to earth at all! They detect an imbalance between the live and neutral current feed to your house.
Best to isolate circuits and see which circuit trips the RCD. (This is tedious I know but it’s the simplest way to find the culprit)
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Believe me, I’ve been isolating and testing for more than a year. To many trips with power switching and cable thefts in town, to much of a coincidence.
Trust me! I’m a doctor 
Bet you it was “shockingly” cold … ? 
Speak to a Installation or Master Electrician on the matter. Their work, their CoC so you can have trouble free electricity.
I’m no electrician. I can’t give you a COC. But I live in an area where, for a time, there was a lot of theft from or vandalising of substations. So we had the RCDs tripping, the shocks from taps etc. And mostly the problem was not the earth but the neutral.
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The danger of sinking your own rod, and (I assume) then making your own TN bond at the point of entry, essentially converting your supply (which I assume is TN-S) into a PME setup (protective multiple earth) is that if the upstream earth you’re all supposed to be using is bad, you have just created a better earth not only for yourself, but for 11 other houses as well. Their fault currents now go via your place…
So I would be very wary of doing this without getting proper advice from a good sparky.
But as Richard said, RCDs don’t use an earth connection, they are not referenced to earth (I have seen some really old ones that are, but no longer). They look simply at the difference in current going in and out. They work perfectly fine even in TT or IT systems. Nuisance tripping means you have a leak somewhere.
If the voltage isn’t fully stable, it is possible that a sharp rise/drop in voltage (transients) could cause leaking through some kind of surge or EMI device, and this surge could cause an RCD to nuisance-trip. Then the solution is to install a transient-resistant RCD. They are somewhat expensive.
I would however attack this in the way I always tell people to do it. Start with an insulation test. Then check your standing leakage. If the standing leakage is above 10mA… consider splitting your circuits into two blocks, each with their own RCD, to halve the leakage on each. That usually solves most nuisance tripping problems.
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A poor or missing neutral will cause the voltage to be unstable, with some phases getting a higher voltage and some a lower one. Might be worth it to check the voltage between your house and some of the neighbours (typically, you’d wire about a third of the houses to each phase to balance things out a bit). You may well find that two phases are high and one are low… which hints towards an issue with the neutral connection.
If the earthing system is TN-S, it means neutral and earth are bonded together at the transformer. In such a system, if you make it PME… you’re going to pass working current on the earth connector. So again, I think that is a bad idea.
This is an angle I hadn’t thought of. Now that it’s clearly stated I smack myself upside the face and say “duh”.
What I was thinking about was ground loops. Having your own local earth whilst the grid has an earth connection which may or may not be connected to a proper earth sounds like a good way to have a ground loop.
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Thanks for all the info. Our problems dit start when the sub was stripped the first time, and of course the cut the neutral first. It caused a lot of damage at some units, others not so much. A few electricians had a go, but I still think there is a network problem. If the local earth route will be done, I suppose the main earth will be disconnected too. Before that, a meggar test will be done in any case, but I can’t take the EL tripping a couple of times on some days, and for days on end there is no problem. My unit is not the only one tripping, but it is awkward to have somebody look after my mains every time we are away for more than one day
What circuits are being supplied by the RCD?
Looks like I’m not going to get an answer.. 
Our house, not only plugs/geysers but light circuits too.
My logic asking sparkies to make it so, if the RCD/EL trips there is a problem - we find it.
Been working sparkingly for +10 years.
RCD/EL should not trip. If they trip it is to save a life i.e. someone was stupid.
… or a device was faulty.
KISS.
Everything works through the EL. But even isolating the live and neutral could nog solve the problem.
I don’t have enough space for splitting them, and a meggar test Is haven’t done. Yet.
The faulty neutral makes me worry. I have checked all the connections om my DB, because faulty connections are always a problem. The three phases are split between the units, and the units I regularly check is not even on the same phase. But our electricity supply is is not stable because of all the ring feeds and theft. With tripping up to four times a day, for the late three days not one!
The more dangerous issue is a faulty neutral from the transformer up to the distribution point inside that housing estate (or whatever). Basic electric theory mandates that if your phases are perfectly balanced, there is no current on the neutral conductor. For loads where you know the three phases are exactly balanced (eg, three phase motor) you don’t even need the neutral connector, just three wires are enough.
But then by the same logic, if the neutral is missing, but the phases are quite well balanced by chance, you might be able to limp along without realising that neutral is missing, or lacking. The only thing that happens in such a system is the phases with the highest load gets the lowest voltage, and conversely, the phases with lower load gets higher voltages.
After a cable theft, this typically manifests with some houses blowing garage door motors and other appliances because they get too high a voltage, while other houses burn out refrigerator motors because they got too low a voltage.
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My understanding is that three phase supply is unusual in domestic applications these days since there’s no need for 380V. Yes, when you need more power a three phase supply will be provided but it isn’t needed: 220V is what is needed!