[Question] Poor Neutral/Earth Bond - Stubborn Nuisance Trips

[Ewaldvdh]

Good Morning to the forum.

I have a challenge that has been haunting my days and my nights for a while now. Of course the good people at Ekurhuleni are shining in their lack of interest and skill in problem solving. Also to note I am not a qualified electrician; at best I am a talented amateur.

Problem Statement -

Nuisance Trip that cannot be identified.

My Setup -

220V Single Phase [Supposed to be 80A] Municipal feed; with 9 KW inverter, panes and 5KW battery pack

What has been done to now

Multiple Electricians have been onsite for this; have done insulation tests; have gone through everything at least three times.
Have split neutral rails
Have removed light circuits from earth leakage
Have replaced surge protectors on DB board
Have replaced wiring to geyser which was compromised
Have fixed one or two plug points which were identified in testing to be "not so good"
Have been told by the last electrician that he did the insulation test from the municipal side and there is no issue with that - although the readings he showed me was taken at two points after the mains [which was switched off] - so not sure what was actually tested, and to be blunt about it; I had to convince the gent that the zero export on my inverter actually does not mechanically clamp current but provides a measurement that allows the inverter's firmware to reduce output to that link to maintain a "negative pressure". I just got gatvol of having to argue with someone so absolutely convinced that I am wrong because I am not a qualified electrician that I left it at that.
Added another RCB to the circuit. 1 RCB for non-essential load e.g. geysers and 1 RCB for essential load [on the inverter return] for everything else.
None of the sub boards on the property has RCB's to interfere; they have rated 2 pole isolators only [30A/ 63A /40A etc tailored for wire gauge and load]
Have replaced the RCB feeding the geysers with a "Super De-sensitized" one.
Have replaced the RCB [which is the one now tripping occasionally - Read once or twice a day]
Ekurhuleni replaced the feeder cable from their "corner box" about 2 years ago but I don't believe that is one piece of cable, I am reasonably convinced it is cut and crimped at every driveway it crosses and I know it is joined to the old cabling going into my "outside wall box" because I have dug that up to verify
Confirmed that the at least 500mm the electrical cable is supposed to be submersed is in fact in places as shallow as 150 - 200 mm
Checked every screw join on every CB
Replaced any CB that was cheapies with CBI / Hager / Siemens [I have 4 Sub DB-S and 1 Main DB with a mix of DIN and Minirail breakers]
My neighbors reported "unspecified work done" by the municipality which included digging up a piece of road and their paving right where their feeder cable would be - after which my trips went from many to very few but still an issue

What has improved -
I have gone from multiple trips a day to maybe one or two and sometimes none
It no longer trips continuously in the rain


My thoughts -
I can show that the earth on the municipal "corner box" is burnt out - have pictures
A couple of years ago the municipality moved that collection point; which was outside my fence to the street corner; joining the 10 odd houses' cabling at that point in what looks like spaghetti. It is a mess and; it is barely below the surface.
I have had to wire my prepaid meter to use live and earth [outside of the earth leakage circuit] instead of live and neutral because otherwise I am unable to see what units I have left and am unable to load new units. I.e. Neutral is compromised. Of course that is not because of the municipality feed I am told, it MUST be something on my property. Yet; if I switch off everything in the house at the mains and connect the console unit to live.neutral pair at the wall box outside I still cannot communicate with the controller. Switch that to Live/Earth then I can
Also tripping issue was an issue before the inverter was installed
My Neighbors next door had a second phase added to their property for an industrial sewing machine they use. Read a lot about harmonics disturbing the waveform and creating nuisance trips [their cabling runs parallel to mine]; my ability to connect my prepaid meter unit stopped around the time that was added for them.
The municipality didn't dig up the ground and pull a new cable through for them; likely because I am supposed to be on 80A instead of 63A they jumper that to my link, and my neighbor didn't get a three phase meter added or for that matter an additional meter; meaning I am most likely paying for the electricity they are using on that phase
Also likely that that is one of the reasons why the chiefs at the municipality is completely ignoring my complaints about this because they know that there is a problem
My last electrician rather angrily highlighted to me that RCB's does not trip when the imbalance is on the feeder side; yet I have enough articles showing noise from an external source as root cause for nuisance trips. This seems to be a pattern repeating.

My inverter is reporting 6V floating voltage from the feeder side

I am at wits end to be frank however; to the point of all of this - - My ask please :

with all of the above noted - - the one thing I can still do is try to minimize the possibility that because of the bad earth on the municipal box; the fact that the bulk of the cabling makes a turn at my house first; the fact that I have about four earth spikes [Electric Fence; Solar Panels; Wall Box; +1 on opposite side of the property] it is possible that I am the earthing point now [path of least resistance].

What are the legalities of doing an earth/neutral bond at my wall box and ignoring everything else; will it have any negative impact if I did that. [not asking if it will solve my problems because it is clear that the majority opinion will be that it isn't municipal feed causing my issues despite every action on the source feed altering the behavior and pattern of the trips]; just will I create more issues if I do, do the neutral/earth bond at that point.

Thanking you all in advance

[Derlyn]

Not a good idea having multiple sub db's all supplied through the earth leakage on the main db.

First step is to remove the supplies to sub db's from the main earth leakage and install an earth leakage in each sub db.

If the main earth leakage still trips, then at least you have eliminated all the sub db's and their supply cables.

[Alfred M]

I agree Derlyn at least isolate sub db when main RCD trips intermittently. There could be many different problems when experienceing RCD intermittent tripping. You are not a qualified electrician (talented amateur) but you are questioning multiple electricians or electrical contractors? Why do you suspect the mains incoming supply surely the contractors would have ruled that out with loop impedance test at point of supply (ZE) and PFC (prospective fault current)at point of supply with main earth disconnected from point of consumption.Polarity test at point of supply and supply voltage no load supply voltage with load L-N (230v) L-E(230v) N-E(0v or above 20v problem indication on point of supply) .RCD intermittent tripping can be complicated as it could be residual currents between L-N and N-E. Was a ramp test done on RCD. Was a residual current clamp used between L-N on point of consumption( bottom of RCD with load connected). It could be 1 faulty appliance or a combination of appliances. There is a comprehensive write up on this forum from Andy about RCD logic.Remember if you are not qualified to work on electricity be extremely careful of perimeter supply boxes(Budgie box) as they are not protected by earth leakage(RCD) one mistake could be fatal.

[GCE]

What are the legalities of doing an earth/neutral bond at my wall box and ignoring everything else; will it have any negative impact if I did that. [not asking if it will solve my problems because it is clear that the majority opinion will be that it isn't municipal feed causing my issues despite every action on the source feed altering the behavior and pattern of the trips]; just will I create more issues if I do, do the neutral/earth bond at that point.

Thanking you all in advance

Only the supplier may earth the neutral - By earthing the incoming neutral to earth you could become the star point for the transformer in the street and you could end up melting your incoming neutral wire if there is a bad connection in the sub station or worse your cable could catch fire.

If you really think it is a problem , maybe as a test , install an earth from neutral to a earth spike and place a 60 Amp circuit breaker in line with the earth - At least then if your neutral becomes the star point and starts drawing excessive current it will trip the CB and disconnect " your star point"
I would not leave it for more than a day or 2 .

As mentioned by other's - RCB's will see a cumulative leakage to earth from the various appliances , the more appliances on a RCB the increased chances of intermittent tripping happening . We generally install 2 or 3 in a house depending on the qty of appliances - My own house I had 5 as my tolerance level for dealing with intermittent tripping units is low.

I have had RCB tripping problems on problematic incomers especially on overhead lines on windy days but it is unusual.

We find that inverters that are grid tied and zero feedback set , still feed back onto the grid when there is a sudden change in load , not much but up to 250w spikes - Have you tried not using your inverter for a day or two to see if it makes a difference

[Ewaldvdh]

Only the supplier may earth the neutral - By earthing the incoming neutral to earth you could become the star point for the transformer in the street and you could end up melting your incoming neutral wire if there is a bad connection in the sub station or worse your cable could catch fire.

If you really think it is a problem , maybe as a test , install an earth from neutral to a earth spike and place a 60 Amp circuit breaker in line with the earth - At least then if your neutral becomes the star point and starts drawing excessive current it will trip the CB and disconnect " your star point"
I would not leave it for more than a day or 2 .

As mentioned by other's - RCB's will see a cumulative leakage to earth from the various appliances , the more appliances on a RCB the increased chances of intermittent tripping happening . We generally install 2 or 3 in a house depending on the qty of appliances - My own house I had 5 as my tolerance level for dealing with intermittent tripping units is low.

I have had RCB tripping problems on problematic incomers especially on overhead lines on windy days but it is unusual.

We find that inverters that are grid tied and zero feedback set , still feed back onto the grid when there is a sudden change in load , not much but up to 250w spikes - Have you tried not using your inverter for a day or two to see if it makes a difference

-- Thank you for the suggestion; I will try and isolate the inverter for a day or two as a test. I have tested it the other way around - e.g. If I leave the municipal feed isolated I have no trips at all.

[Ewaldvdh]

Not a good idea having multiple sub db's all supplied through the earth leakage on the main db.

First step is to remove the supplies to sub db's from the main earth leakage and install an earth leakage in each sub db.

If the main earth leakage still trips, then at least you have eliminated all the sub db's and their supply cables.

-- Thank you for the suggestion. I do want to note that I had it originally that way around but was instructed to change that around. Will give that some thought. I have done a bit of work in testing; e.g. left each individual sub except for the one supplying my Internet and LAN off for extended periods of time an the trips does persist, but your logic is sound

[Dave A]

That prepaid meter only working on earth and not on neutral is a bit telling.

Make sure that all neutrals are wired to the correct neutral bar (the one related to where the live is coming from).
While a crossed neutral on a live coming on the load side of an RCB will trip instantly, we recently had an instance of a neutral connected to the municipal supply neutral bar while the live was fed from the inverter (light circuit so it wasn't on earth leakage). When the municipal supply dropped, no problems were experienced. But when the municipal supply came back on, the RCB tripped as the inverter crossed to bypass mode (despite this neutral problem being on the load side of the RCB). Moving the neutral to the neutral bar for the inverter for circuits not on earth leakage solved the problem.

[Ewaldvdh]

Only the supplier may earth the neutral - By earthing the incoming neutral to earth you could become the star point for the transformer in the street and you could end up melting your incoming neutral wire if there is a bad connection in the sub station or worse your cable could catch fire.

If you really think it is a problem , maybe as a test , install an earth from neutral to a earth spike and place a 60 Amp circuit breaker in line with the earth - At least then if your neutral becomes the star point and starts drawing excessive current it will trip the CB and disconnect " your star point"
I would not leave it for more than a day or 2 .

As mentioned by other's - RCB's will see a cumulative leakage to earth from the various appliances , the more appliances on a RCB the increased chances of intermittent tripping happening . We generally install 2 or 3 in a house depending on the qty of appliances - My own house I had 5 as my tolerance level for dealing with intermittent tripping units is low.

I have had RCB tripping problems on problematic incomers especially on overhead lines on windy days but it is unusual.

We find that inverters that are grid tied and zero feedback set , still feed back onto the grid when there is a sudden change in load , not much but up to 250w spikes - Have you tried not using your inverter for a day or two to see if it makes a difference

Morning - Thank you for this; I will give that a go. It also speaks directly to where my mind is that; which is that I think I am already the star point to some degree - given the fact that the earth strap in the corner box is literally burnt out and that I am moderately certain I have more earthing than most of the neighbors. Happy to accede if that is not possible; like I said I might be overthinking this a bit.
Noting the +1 on splitting out DSUBS to have their own RCB's. Definitely worth prioritizing for the one feeding the pool and my office space. I have another unit in my garage space which only pulls the garage motors; a set of plug points and a single light source; and a unit feeding a small flatlet which is unoccupied and has nothing drawing current there at the moment.
One Last thought; Reading up on cumulatives contributing to the 30 milli amp that would constitute a trip, I will accede that it is a possibility; however noting that I have very few power supplies running that does not have at least EU certification; my appliances are reasonably new; e.g. I have gotten rid of the bulletproof 30 year old fridge and freezer; they geysers are on a separate earth leakage; the pool pump and the bulk of my electronics are new [thanks to the municipality pushing 380V down the line late last year] and the power supplies feeding my PC's are high spec quality units chosen specifically with efficiency and circuit protection quality aspects.

[Ewaldvdh]

I agree Derlyn at least isolate sub db when main RCD trips intermittently. There could be many different problems when experienceing RCD intermittent tripping. You are not a qualified electrician (talented amateur) but you are questioning multiple electricians or electrical contractors? Why do you suspect the mains incoming supply surely the contractors would have ruled that out with loop impedance test at point of supply (ZE) and PFC (prospective fault current)at point of supply with main earth disconnected from point of consumption.Polarity test at point of supply and supply voltage no load supply voltage with load L-N (230v) L-E(230v) N-E(0v or above 20v problem indication on point of supply) .RCD intermittent tripping can be complicated as it could be residual currents between L-N and N-E. Was a ramp test done on RCD. Was a residual current clamp used between L-N on point of consumption( bottom of RCD with load connected). It could be 1 faulty appliance or a combination of appliances. There is a comprehensive write up on this forum from Andy about RCD logic.Remember if you are not qualified to work on electricity be extremely careful of perimeter supply boxes(Budgie box) as they are not protected by earth leakage(RCD) one mistake could be fatal.

Thank you for the reply.
I will look for the writeup from Andy, and I will prioritize splitting out DBSUBS. I think one point to note; if I switch off the municipal feed in the Budgie Box and run on Solar; Batteries and Supplementing any shortfall with a genny I do not have any trips at all.

As to the testing done; yes a ramp test was done I believe; no fault found. One contractor spent nearly a full day onsite taking each individual neutral off the rail and testing each individually which showed that the neutral on the main geyser was burnt; the isolator on the one gate motor was not making a solid connection and all together two plug points were replaced as they were suspicious. All the circuit breakers in the house have been replaced; and I have done a significant amount of work trying to isolate the circuits individually; i.e. leaving a different circuit off over an extended period of time.

To the point of why I am questioning qualified individuals with years of experience; I have done more than my fair share of troubleshooting systems, people and process, and have learnt through experience that especially the more qualified you are; you have formed opinions based on experience and lessons learnt and tend to consider a problem based on those experiences. I would like nothing more than to say; thank you; job well done; appreciate the effort and time but reality here is I have spent thousands upon thousands to try and get this sorted; have done the tests and paid the dues. The one thing that is however constant is that this cycle of trips have been around from about 5 months after I moved into this house; about 8 years later; every time it has stopped has been after something was done on the municipalities side and everything I have done internally have been to moderate and try to reduce this cycle.

Naturally that is the perspective I depart from whereas someone with years of experience and training with a particular thought process [justified based on experience and knowledge] seems to completely discount the fact that that is my set of experiences. I also did research towards external factors cumulating towards RCB trips and have found sufficient documentation indicating this is possible while not frequent. What irks me is that professionals discount what I believe to be an informed opinion based on research and personal experience of the actual problem being discounted simply because it is not the usual status quo.

Again I am not discounting knowledge and experience until that becomes a limiting factor in vision to allow for the fact that sometimes; just sometimes; there may be something else at play and a bit of out the box thinking might be required.

[Alfred M]

Intermittent RCD fault could be tricky to any experience electrician especially if it is a neutral to earth fault try to get a electrical contractor with a residual current clamp to exactly measure the balance between L-N at the RCD ans see how much leakage is present with load connected. Apart from that every curcuit every wire should be tested for insulation breakdown(megger test at 500volts but all sensitive equipment must first be removed even the lights when doing this insulation test it could be something simple like a bulb fitting or a light switch or maybe some cable outside breaking down. Or a wire in the roof that is comprised. It could be a multiplug with surge protection the list is endless but with systematical elimination the fault will present itself patience and due diligence is the key in these types of fault.

[Justloadit]

Just a note about all new electronic equipment.
They are usually fed with an SMPS (Switched Mode Power Supply) due to universal input, cost and physical size.
One way of getting to pass the EMI limit specifications is to add a small capacitor between the secondary negative line and the incoming rectified negative line, and some of the systems depending on the type may have a capacitor to earth to reference the secondary side to earth. You can usually note this when you touch the chassis of 2 computers and get a tingling feeling, or noted a spark when connecting 2 computers via USB or in the old days RS232. Use you AC tested to measure the voltage between your PC chassis and Earth to see this.
A number of these SMPS connected could increase the leakage current from Neutral to Earth when there is a spike somewhere in the electrical system, which could cause the RCD to trip.

[Ewaldvdh]

Just a note about all new electronic equipment.
They are usually fed with an SMPS (Switched Mode Power Supply) due to universal input, cost and physical size.
One way of getting to pass the EMI limit specifications is to add a small capacitor between the secondary negative line and the incoming rectified negative line, and some of the systems depending on the type may have a capacitor to earth to reference the secondary side to earth. You can usually note this when you touch the chassis of 2 computers and get a tingling feeling, or noted a spark when connecting 2 computers via USB or in the old days RS232. Use you AC tested to measure the voltage between your PC chassis and Earth to see this.
A number of these SMPS connected could increase the leakage current from Neutral to Earth when there is a spike somewhere in the electrical system, which could cause the RCD to trip.

Thank you to you and to everyone else on the thread; the guidance and advice is appreciated. I also want to add that my replies are made with the intent to not discount any guidance or advice; it is in the interest of accounting for where I have given consideration prior; my motivations based on my own limited understanding and steps taken to try and resolve this nuisance trip issue.

I will admit that the bulk of the technical aspect of what you are describing is while fascinating for me; has mostly gone over my head. I understand the absolute basics only around the use of bridge rectifiers; converting AC to DC and the use of a step down transformer; adding to that only that I have an awareness that there are generally smoothing caps used to normalize the wave form and some additional filtering and circuit protection added. I know only enough about modern circuits to be able to identify components; do some basic checks with a multimeter and if there is visible damage to a component to desolder and replace and hold thumbs it doesn't go boom. However I appreciate the knowledge share and like I said; it is an area of interest. I do want to point out that it is an area of consideration; having encountered less expansive writeups on this topic before; coupled to a lifetime of building up desktop PC's and experiencing the tingles and arcs you refer to, leading me to the fact that all the compute devices in my house that would normally be accompanied by switch mode power supplies are quality units; equivalent to Corsair; if not Corsair psu's; I made sure of that. The smaller compute devices only has linear outputs on their PSU's; if the terminology is correct. I got rid of the hi-fi's; surround sound systems etc. [or to be more correct; I didn't replace them after these went boom when Eskom pushed their 380V down my line and the insurer noted that because these have not been listed it isn't covered]

[Ewaldvdh]

Just a note about all new electronic equipment.
They are usually fed with an SMPS (Switched Mode Power Supply) due to universal input, cost and physical size.
One way of getting to pass the EMI limit specifications is to add a small capacitor between the secondary negative line and the incoming rectified negative line, and some of the systems depending on the type may have a capacitor to earth to reference the secondary side to earth. You can usually note this when you touch the chassis of 2 computers and get a tingling feeling, or noted a spark when connecting 2 computers via USB or in the old days RS232. Use you AC tested to measure the voltage between your PC chassis and Earth to see this.
A number of these SMPS connected could increase the leakage current from Neutral to Earth when there is a spike somewhere in the electrical system, which could cause the RCD to trip.

Maybe a question here - would it be worth replacing the RCB with an SI unit; and would you perhaps be able to guide me to one that will fit on a mini rail?

[Justloadit]

Maybe a question here - would it be worth replacing the RCB with an SI unit; and would you perhaps be able to guide me to one that will fit on a mini rail?

According to the statements made about the SI unit, it may be a viable option.

[Alfred M]

Day night switches and motion detectors all small electronic devices use x- rated capacitor supply or dropper power supply where the low voltage is not mains isolated faulty day/ night or motion detection could also be problematic for RCD's.

is