Hi all. Hoping somebody here can give me some advice on an ongoing issue im experiencing.

A while ago almost every device in the house with some form of ac-dc conversion in it started making a noticeable high pitched whine/buzzing noise. There had been no load-shedding for a while at the time.

Things i have checked:
voltage appears normal 230-237v
checked for any bad connections inside the db
voltage between live-earth and live neutral is the same
disconnected everything in the house and then tried just one of the affected devices - noise is still there
ceiling fan's seems to spin at a normal speed(maybe a slight hum but not sure if this was always there)
If i disconnect from eskom(mains cb and earth leakage off) and run everything from an inverter or generator there is no noise. Which seemingly rules out an issue with the wiring inside the house.
If i use the affected devices at a house in a different area they make no noise.
neighbors claim to not notice anything, but not convinced that they dont have the issue too.

Info on the installation
We have no inverter backup wired into the house(inverter trolley that i would feed in during load-shedding)
we have a pre-paid meter
We are in the parklands area which is eskom direct... i have had no luck getting something logged with eskom since it doesn't match any of their "outage" options. And an electrician is surely going to do the same checks ive alreday done but at a price...

Maybe this is just coincidence but at the same time this started the house directly opposite from us was having an inverter installed(battery backup only as far as i can tell). There was also eskom maintenance happening a few blocks away from us on the day. Could it be either of these?

So my question, where to go from here. Is there a way to get an eskom engineer to come and check if the sine wave is within spec on both sides of the meter?

Any help is appreciated thanks

21 minutes ago, The_Stig said:

Maybe this is just coincidence but at the same time this started the house directly opposite from us was having an inverter installed(battery backup only as far as i can tell)

If you're on good footing with the neighbour across the road, maybe ask him, for testing purposes to turn off his inverter, for 10 minutes while you and him check whether this quietens your affected devices.... if it does, the supplier of his inverter would probably have to get involved...

2 hours ago, The_Stig said:

If i use the affected devices at a house in a different area they make no noise.
neighbors claim to not notice anything, but not convinced that they dont have the issue too.

Power problems can be quite localised. Where I live we have poles carrying cables along the street. Each cable supplies three properties. We have twice had issues that affect only the properties hooked up to a specific pole. In one case it was a lost neutral connection. In the other (which affected me) it was very low voltage (like down in the 180s) in three houses only.

So an update. I bought one of these filter plugs just to see what would happen.

It does actually seem to work, anything plugged into it is now silent...the plug itself makes a bit of a noise though.

My understanding of this is that the issue must be some high frequency interference? Could this be a failing eskom transformer or an issue with switch gear somewhere?

An electrician was also here just to take a look, found nothing initially but mentioned that it could maybe be insects inside a plug somewhere? But I would have thought turning off all the plug circuits and trying them only by one would have made a difference.

On 2025/04/11 at 12:58 PM, Kalahari Meerkat said:

If you're on good footing with the neighbour across the road, maybe ask him, for testing purposes to turn off his inverter, for 10 minutes while you and him check whether this quietens your affected devices.... if it does, the supplier of his inverter would probably have to get involved...

With regards to asking the neighbors they were unwilling to assist, saying it is impossible. I have no proof so could not really argue...

9 minutes ago, The_Stig said:

Could this be a failing eskom transformer or an issue with switch gear somewhere?

Nope, this is high frequency on the mains end, probably from a neighbours inverter that is injecting power to the grid, I'd be willing to bet... a nearby neighbour, though, cabling wise... maybe chat to Eskom to investigate, else they can briefly switch off the neighbour across the road at the DB in the road... and see whether that makes things go quiet your side...

11 minutes ago, The_Stig said:

could maybe be insects

what kind of electrician is this? this is a most idiotic statement, I'd say...

My 2c worth would be it is not due to transformer or switchgear causing the high frequency. Frequency to my mind cannot be created but is injected from a consumer as @Kalahari Meerkat mentioned. At least the good thing is that the filter is helping.

1 minute ago, Kalahari Meerkat said:

Nope, this is high frequency on the mains end, probably from a neighbours inverter that is injecting power to the grid, I'd be willing to bet... a nearby neighbour, though, cabling wise... maybe chat to Eskom to investigate, else they can briefly switch off the neighbour across the road at the DB in the road... and see whether that makes things go quiet your side...

Indeed. I feel it has to be that as well. Battery only system though, so it really should not be trying to feed back? eskom were out here too but since the voltage was "fine" they refused to open the distribution box on the street.

I guess its a case acquiring an oscilloscope to provide proof that there is an issue, and go from there.

8 minutes ago, The_Stig said:

Indeed. I feel it has to be that as well. Battery only system though, so it really should not be trying to feed back? eskom were out here too but since the voltage was "fine" they refused to open the distribution box on the street.

I guess its a case acquiring an oscilloscope to provide proof that there is an issue, and go from there.

With a scope one will see the 50Hz power and superimposed on it the high freq noise signal. But then one must still find the source. This is perhaps why Eskom do not want to try and find the problem.

4 hours ago, The_Stig said:

they refused to open the distribution box on the street

Time to get a sidekick and some keys and some late night switching off of various customers for 10 seconds at a time... with a pair of UHF handhelds or some VoIP cell connectivity between inside your house and your sidekick in front of the DB in the street... else... yes Oscilloscope, but this won't pin point the source...

Edited April 14Apr 14 by Kalahari Meerkat

Been doing some more research on this problem.

I'm suspecting the guys accross the road may have an incorrect earth neutral bond. As I understand it this can create a feedback loop and cause exactly the issue I have.

Assuming I'll never come right getting them to check/correct the issue, is there anything than can be done on my end?

If you can get a power quality analyser and show that a specific harmonic is out of bounds, you can request to be put on another phase.

On 2025/04/14 at 5:35 PM, Kalahari Meerkat said:

Time to get a sidekick and some keys and some late night switching off of various customers for 10 seconds at a time... with a pair of UHF handhelds or some VoIP cell connectivity between inside your house and your sidekick in front of the DB in the street...

It will be interesting, but also fruitless. If you knock on the neighbour's door and ask him to do something about the noise his system is generating what is he going to do? Say "oh I'm sorry" and disconnect the system that he bought because he needs it? Eskom are unlikely to go and tell him he's breaking SANS such-and-such.

I'm wondering if it has to be a something generating back into the grid. I remember many years ago I was working for an IT company in the South of JHB. They had intermittent power problems that were eventually traced to a panel beater up the road. This was about 1988. The company was trying to sell fault tolerant hardware that came in from the US. The problem was that you could pull disc drives and processors out of the machine whilst it was running and it would carry on, but the moment that panel beater fired up a certain piece of equipment the hardware demonstrated that it was not tolerant of that particular problem and would promptly stop. In the end they put lots of earthing straps on it and stuck it inside a faraday cage. Which was not the best advertisement.

Edited April 18Apr 18 by Bobster.

32 minutes ago, Bobster. said:

If you knock on the neighbour's door and ask him to do something about the noise his system is generating what is he going to do? Say "oh I'm sorry" and disconnect the system that he bought because he needs it?

You're missing the point here, first you need to identify the source then you can consider what you can do about it.

Its like people with their electric fences who don't maintain them and cause RFI, you could, if the culprit is unwilling to fix the issue, get ICASA involved, since having an arcing fence is the same as running a spark transmitter, where there are serious fines that can be levied, I believe more than 1MZAR, but I could be wrong and it may *only* be a couple of 100kZAR, fine for the sparc transmitter.... I suspect the culprit may prefer to do a little cleanup and maintenance around his electric fence rather...

So if you are against identifying the source... what is your suggestion? The Faraday cage for @TheStig, that is unlikely to sort out the issue, since its entering his home with the power cabling infrastructure, it seems, so what now?

Edited April 18Apr 18 by Kalahari Meerkat

53 minutes ago, Kalahari Meerkat said:

You're missing the point here, first you need to identify the source then you can consider what you can do about it.

I think I did understand that. In my experience neighbours aren't always obliging when they have something that's interfering with something of yours.

53 minutes ago, Kalahari Meerkat said:

Its like people with their electric fences who don't maintain them and cause RFI, you could, if the culprit is unwilling to fix the issue, get ICASA involved, since having an arcing fence is the same as running a spark transmitter, where there are serious fines that can be levied, I believe more than 1MZAR, but I could be wrong and it may *only* be a couple of 100kZAR, fine for the sparc transmitter.... I suspect the culprit may prefer to do a little cleanup and maintenance around his electric fence rather...

Well I agree in a way. I just think that these services are not up to much at the moment, and whilst one might have a case in terms of the law and regulations, nobody's likely to do much except acknowledge receipt of your mail.

We have schools and businesses in our area that are clearly breaching by-laws. Our elected representative for the area agrees and has spoken to the relevant City departments. Does anything happen? No.

OK... I'm Mr "The glass is 1/8 empty"

29 minutes ago, Bobster. said:

We have schools and businesses in our area that are clearly breaching by-laws. Our elected representative for the area agrees and has spoken to the relevant City departments. Does anything happen? No.

There's always the story of the Sheriff of the Court looking to augment his income, that could be nudged with a couple of 100ZAR's to lean on the offending person owning the noise source, a la, "Nice house, it'd be a shame if it burnt down due to your electrical issues..."

With regards to "dirty power" I guess, yes one can buy noise filters, but over the long-term surely this is not sustainable. Do these noise filters not also suffer from heat issues (am asking from one unfamiliar with them, by the way) and is there no way of getting a type that can be put at the mains input to a property which would then cover one's whole property instead of individual ones per each socket?

On 2025/04/18 at 10:38 PM, Moffat said:

noise filters

According to me you still want to identify the specific harmonic frequency that is present. A generic filter may not solve the issue and yes, heat could be a problem.