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Electricity Through the Plumbing


VisN
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We're experiencing some issues at home with our electrical installation. First the plugs started tripping intermittently, some light bulbs started popping and now we're feeling light jolts when touching the taps. 

What could be the issue?

Could anyone recommend a good electrician in Midrand?

 

Thanks.

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On 2020/03/30 at 2:42 AM, VisN said:

now we're feeling light jolts when touching the taps. 

Sounds like you're having issue with earthing, and the trips may be the RCDs (Residual Current Devices). Check for a green and yellow [ edit: or bare copper ] wire that connects to either copper pipes, or some sort of earthing stake. It might even be repairable without an electrician, if it's just corrosion or loose clamping, etc. But turn off the power when fiddling with this, as it could be a lot more serious.

Edited by Coulomb
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1 hour ago, Coulomb said:

Sounds like you're having issue with earthing, and the trips may be the RCDs (Residual Current Devices). Check for a green and yellow wire that connects to either copper pipes, or some sort of earthing stake. It might even be repairable without an electrician, if it's just corrosion or loose clamping, etc. But turn off the power when fiddling with this, as it could be a lot more serious.

Thank you very much. I cannot find a stake within my boundary walls, I will look at the incoming box from the council.

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As a start, use a volt meter and measure from earth to neutral. You want this to be as close as possible to zero, preferably no more than a few hundred millivolts. Do the same test between a copper pipe and earth, and a copper pipe and neutral to get an idea of what side the piping is on. For example, if you have your copper piping tied to the electrical earth (which is common, it is done at your geyser to mention just one place), and if you then lost your earth connection (the physical connection to an earth spike, which may not be on your premises), then earth will float up to somewhere between 60V and 100V in my experience, and it will take the piping with it.

You should also measure the overall voltage, check if that is stable. There are other things that can happen, like a lost neutral in a TN-C-S setup, which causes one leg to go high impedance and will be visible as fluctuations in your supply voltage. Of course it gets even more serious in a 3-phase setup if you lose a neutral. But I'm not really putting my money on this possibility. I suspect you lost earth, but the TN bond is still in place, so everything is being pulled up to roughly half the supply voltage.

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1 hour ago, VisN said:

I had an electrician over and after much measuring and checking, he found that the voltage coming into the house is around 261V. This is a problem on the council's side.

Lost neutral on the council side. Three phase, so the enter point of the delta floats in the middle depending on the loads on each phase, and the voltage divides by the same token. Whichever phase has the least load gets the highest voltage.

One of your neighbours likely has a low voltage problem. Think about it like this: Imagine you and your neighbour are sharing a single 400V supply, and your houses are wired in series. the one with the smaller loads is going to get the higher voltage. If the neighbour makes a dead short... you'll get the full 400V on your end...

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1 hour ago, VisN said:

What should the reading be when measured as can be seen below?

That should measure zero or very close to zero. I can't quite see what range it is on or where the decimal point is. 315mV is fine. 3.15V is fine. 31.5V is reason for concern, but not switch-this-shit-off-it-is-dangerous territory. 315V is of course a big problem...

What I would also like to see is live to earth... and then stick one peg into the actual earth at your feet, and measure all three again...

Edited by plonkster
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3 minutes ago, plonkster said:

What I would also like to see is live to earth... and then stick one peg into the actual earth at your feet, and measure all three again...

So to be clear, what would be interesting is:

1. Live to earth cable

2. Neutral to earth cable

3. Live to Neutral (you said 265V earlier).

What I expect is that adding numbers measured at 1 and 2 will give you the same value as 3.

Then stick one end of the multimeter into the earth at your feet (best if it isn't bone dry), and measure:

4. Live to earth

5. Neutral to earth

6. Earth cable to earth.

Now that last one should preferably not show any voltage at all...

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1 minute ago, plonkster said:

That should measure zero or very close to zero. I can't quite see what range it is on or where the decimal point is. 315mV is fine. 3.15V is fine. 31.5V is reason for concern, but not switch-this-shit-off-it-is-dangerous territory. 315V is of course a big problem...

@plonkster, that measurement was 31.58V 

However this afternoon, after another tripping incident I measured again and got 159.7V

image.thumb.png.ca8170a50e94e20272cfc9def54439e3.png

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It turned out that someone had interfered with the kiosk box that served my property. There was some dodgy wiring present in the box which was immediately evident to the naked eye due to the presence of what looked to be a rogue wire and insulation tape. City Power's response and fixing of the problem was nothing short of extremely impressive, under 24 hours from logging to closure. 

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