Earth leakage trips in different buildings

Hi Guys, I am reaching out simply because I am out of options. I`ve been struggling with this problem for 8 months now. So basically our system feeds from one main DB then there is a Isolator feeding to the factory (3 Phase) with a 35mm 4 core armored cable. Then there is the house that has been split into two, there is a Isolator in the main DB that feeds to the 1st house with a 6mm 4 core cable (3phase house), From there with a 6mm Cable it feeds the second house ( connected on the top of the previous main) and from the 2nd house (3 Phase) it feeds to the office which is a separate building about 100M from the houses. It runs with a 10mm cable and the office is single phase.

So my problem is the following. Firstly the office building has been randomly tripping only at night time when there is literally just the CCTV system, Fridge and a UPS that is running, We heave removed the lights from the Earth leakage to see if there isnt maybe a fault in the wiring. Ive left everything unplugged but still tonight it stays on, tomorrow night it trips, it is never at the same time and there is no pattern. Iv`e replaced the Earth leakage, checked the earth, Meggered the cable, checked all of the connection, but still it keeps on tripping.

Now last week I was informed that during the weekend the factory earth leakage was tripped, as they switched it on the office tripped but factory stayed on, they came to the office, when they switched it on again the factory tripped immediately, they then went and switched the factory on again and everything stayed on.

Just to give a little perspective, the factory closes at 5pm Monday to Friday, the only thing in the factory is the CCTV system that runs through a UPS with surge protector plugs and it only trips while there is absolutely nobody around at night. The office has been tripping during the night aswell even with nothing plugged in. And the cherry on top is these two that tripped each other only feeds from the same main DB with two completely separate Isolators and separate Cables.

I recently finished installing a 150kW solar system so that we can run fully off grid with the hopes that the issue was due to spikes from eskom, but now we are still having the exact same problem, lines are balanced, cables are fine, Earth leakages are replaced, so can anyone PLEASE give me some advice as to what can be the problem???

Have you tried to remove that UPS from the equation ?|

If UPS is a must, try a different brand for a night or so, or even a few nights without it.

Welcome, Jan.

Reading what you wrote, one of three options?

  1. What Tinuva said.
  2. Have the sparkies test every single circuit, the EL, the earth with their appropriate tools?
  3. DIY (spitballing). You say 5pm and weekends all off (?), trip al breakers bar the EL on both boards. Monitor it for a week(?). After a week, leave the first group of breakers on, the following week the next group till you maybe find the group causing the issue, then identify the one that is causing the issues.
  4. Maybe rats touching an open wire?

Others will come past too …


Maybe the compressor cycle is diiferent with the fridge running at night without anyone opening the door, compared to day time running. Some fridges also have an evaporation tray above the compressor - possibly this overflows at times and causing the trip somewhere?


If both E/L’s affect each other there is a downstream electrical connection that is not being addressed and is common to both earth leakages, You go on to say you have proved there is none in the conventional electrical cabling. (This can be by omission or commission of a circuit).

I don’t like to jump to the rare causes without ruling out the obvious first, but IF you have ruled out the obvious as impossible then:

Are both buildings’ CCTV systems galvanically independent or is there a copper connection between both buildings in the POE supplies or data links? This should be fibre between the buildings.

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No that is the one thing I havent tried, the one in the office has been replaced with a new one aswell as the one in the factory, but ill give it a try.

  1. I`ll try that,
  2. I am the sparky lol and I have tested the EL and even tho it tested fine I still replaced it with a new one to see and I have also tested every single circuit.
  3. literally all that needs to stay on is the cameras. I have done this with the office and left everything off and it still tripped. with just the earth leakage on. The factory I haven`t tried that yet.
  4. I have traced all of the wires that can be chewed and none is open or broken. One thing I forgot to mention though is that the people who built the office building layed 2.5mm flat twin and earth directly on the ground and poured the concrete over it with no conduit nothing and the building has been standing here for about 10 years and the issue started about 4 years back, so I have had a feeling that due to earth movements a cable inside that concrete may have been damaged and at night due to the temp change and humidity it may be possible for damp to rise through the concrete and touch the exposed wire inside IF there is a damaged cable?

So the fridge is brand new and yes it had issues with the compressor and it has been changed to a new one but these issues has been there before the said fridge and after.

We have the Green Surge protector plugs, but what you said there Ill try, I honestly never in my career heard of the surge protection units that influenced the sensitivity, but in the last 2 days Ive been seeing quite a lot about it. And as I mentioned there is a brand new earth leakage installed though.

Ah damn I had a similar issue at home. Somehow someone thought it was a good idea to put the outbuilding wire directly in the ground, but not the shortest path, the longest path all around the house.

It was damaged at one point by people working in the garden. Every winter here in cape town when it rain, the water eventually got to that damaged point and tripped the power. Usually at night while everyone is sleeping.

At least, it was Surfix twin and earth, but still. I had to redo the whole thing myself, put it through the ceiling instead, and only a small part underground, in a conduit dedicated to it.

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@Phil.g00 There is only 2 places where there is even some kind of connection between the buildings.

  1. Is the Common neutral Bus bar that feeds from the Inverter.
  2. The only connection between these 2 buildings directly is a Cat6e Outdoor Network cable joining the PoE Switch in the factory with the PoE Switch in the Office of which the cable runs in a 110mm Pipe underground for about 100 meters.

The people who installed this system initially did this, so how the layout works from back to front is: there is 9 IP PTZ Bullet cameras in the Factory which runs to a PoE switch which uplinks to a Poe Switch in the office about 110M away where 3 more IP Cameras join in the PoE switch, From the office it uplinks to a PoE switch in the Owners house about 40M away where another 5 Cameras joins in and another PoE switch from another location where we dont have issues. From the PoE switch in the house it uplinks to the NVR. This system has been installed like this for about 7 years now and it has been giving its own set of issues as time goes on. Do you think that there could possibly be a connection with the trips with both PoE Switches in the office and the factory that is feeding from 2 Separate UPS`s and each with a surge protector plug? Due to the fact that the 2 mentioned PoE Switches are directly connected with a CAT 6e outdoor cable?

And @Phil.g00 Yes I have definitely ruled out all of the obvious possibilities and quite a few random thoughts that came to mind, this issue has had me going back to my text books from apprenticeship time to make sure I didn`t miss anything.

Just to mention I am a qualified Electrician by trade with about 11 years working experience in the field and 6 years qualified working experienced in the field and I’ve never crossed something like this, usually I found the problem somewhere between the obvious issues and it wasn`t needed to continue searching.

@tinuva Yeah, Our problem is the guy who did it did not even use surfix just plain flat twin and earth and yes he used the shortest path to save on costs at least but he tried to save to much by 1. not using conduit. 2. pouring concrete directly over it (which means the wire is set in the foundation and the floor because he layed the wires while they were busy with foundation and 3. he used the shortest path which means it goes under the walls, thus to fix such a wire is impossible without breaking down the walls and opening the floor through to foundation, and seeing that this doesn`t happen in certain conditions or at more or less the same time it is nearly impossible to determine which cable it is exactly, thus my issue is I kind of firmly believe that one of the cables in the concrete is damaged and due to damp forming through the temp change and the humidity it causes basically “sweat” in the air pockets of the concrete and somewhere maybe due to earth movement the concrete shifted a little bit and damaged the cable now with that “sweat/damp” it shorts out either on live and earth or neutral and earth and the issue is that the owner does not want to believe that that could be a possibility because according to him it is impossible for concrete to shift and also it is impossible for damp etc to get through concrete especially for underneath a building (All according to the owner)

The only thing I always add, is if you have a meter that is capable of measuring the leakage… measure it. If you have a standing leakage of close to 15mA, nuisance tripping always ensues.

Ideally you need a clamp meter that is designed to measure very low leakage currents (you place it around both conductors where it enters the RCD aka earth leakage). I’m not even a sparky, but I got so fed up with “working in the dark”, and since I firmly believe that things that cannot be properly measured cannot be easily improved, I bought the clamp meter.

The next thing I really wish existed, is a device that can be installed that measures and logs leakage current. Here is a somewhat badly implemented version that might work for that kind of thing, a Wi-Fi enabled breaker that can also tell you the measured leakage current.

Because once you get past all the obvious things, to those once-in-a-blue-moon transient stuff that always disappear when the sparky shows up, the only way to find them is long term monitoring.

This post probably doesn’t help… but that’s why I waited for everone else to chime in first :slight_smile:

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Oooo … we have slabs that have been up for 10 years now …

I learnt last year that concrete settles over 30 years. The first 10 years they shrink the most. Next 10 less, last 10 the least.
Hence why one does not tile on them without expansion joints … or have cables inside them that is not in the appropiate trunking.

EDIT: I can see a few mm gap on the sides on the one slab. Where it shrunk.
Tiles on top of it, tickets.
All perfectly normal, Engineers cater for that.

Yes, but the Surge protections, combined, push the overall EL close as damn to the 30mA (or whatnot) point of it having to trigger.

THAT is the problem developing. Then one adds a solar system …

Our house was checked again for CoC, the new additions.

Test shows it is not 30mA anymore, more like 26-28mA (If I understood right) … the nuisance tripping was mentioned.

We left it, IF someting starts tripping, will deal with it then.

We are living in unusual times, to say the least. We have outages EVERY day, usually more than one, with the voltage sometimes getting widely out of range. Substations being turned off and back on multiple times in a day. Where I live we’ve had problems with earths and neutrals being broken or poorly connected.

In another thread (an on a FB group) I’m discussing some unexpected behaviour from my inverter. You talk to guys in Europe or Australia about this and they’re all “huh?”. They don’t know about a world where the power comes and goes at least once every day and where the voltage fluctuates so wildly. And the designers of the inverter probably weren’t thinking about those conditions either, or didn’t spend a lot of test time on them.

If you’re in Gauteng then throw in a recent couple of show-stopper electric storms.

All our electrical equipment is being pushed very hard right now.

Last week there was a lightning strike very near my house. It kicked the garage door motor in to life. It tried to close a door that was already closed, actually put quite a lot of tension into the door, and bent the metal arm that connects the door to the drive mechanism by about 2 cm.

Our next door neighbour had every breaker in his DB trip, and his electric fence energiser was fried.

Yuhp I know all about that and yes we are in Gauteng, our company is built on a farm thus we get a whole lot of those storms. Hence the reason why we decided to go completely off grid due to all the lighting strikes, surges and fluctuations from Eskom. currently were not connected at all so luckily we can rule out that part as were getting a solid supply from the inverter

I installed a Tripconnect to disconnect the house from Eskom/Munic supply when volts go >250v and <215v … my settings … with built-in surge protection.

Exactly to protect the stuff inside the house, including the inverter.

Lightning/thunder, what I saw in Jhb/Pra last week … liewe donner! (pun intended).
There is nothing you can do to protect against THAT! :astonished:
Bar good insurance cover.

Even in cape town I have a surge protector in the DB infront of the inverter. The inverter itself however will also disconnect from grid if the grid voltage or frequency go out of spec. In fact, it has happened in the past where our suburb power went up slow from 240v to almost 300v or something. The whole suburb complained about weird stuff blown etc. When I looked at the history on my inverter, it basically just disconnected and went into offgrid mode while that whole story was going on, until the muni fixed it.

Yes, inverter does.

BUT, the thing that dawned on me one night very late, listening to the fan, having critical and non-critical DBs, the non-critical stuff will still be connected to Eskom, at the high volts.

As you said, when it goes too high, “weird stuff blown” … hence I did this.

Cheaper than going off-grid.

If the two independent E/L systems are tripping sympathetically, I’d conclude that they can’t be independent and there has to be a galvanic connection that is common between both E/L systems.

CAT cable rarely maintains its insulation integrity between remote buildings as it is also a potential earth loop when there is lightning.

Whether it is the cause or not, I don’t know.

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