@GCE. Yes.
@GCE. Yes.
YoU will not believe how many circuit sketches I've made to try and work out how that neutral earth fault can render the test button inoperable, without success. I once spoke about an earth leakage not tripping on an earth fault if there's no load on the output. I even made a little video to prove it. When I have some spare time on my hands, I'm gonna play around on the workbench and see if I can replicate what has happened the last 2 days. Theoretically it shouldn't be possible, but believe me when I say that is what happened. I , however, cannot explain why.
Originally Posted by Derlyn
Try swopping the live and neutral in that diagram, and insert the dead fault between the "new" neutral and earth.
And remember to bridge the earth and neutral on the supply side too (your East London (and Eskom) special condition).
Alternatively, if the test button is between the supply side of the phase conductor and the load side of the neutral conductor relative to the earth leakage sensor, and the neutral is bridged on both sides (via the earth), the test fault bypasses the earth leakage sensor completely (or at least not enough current through the neutral conductor coil to cause a trip).
That zero voltage you have between earth and neutral plays some interesting tricks.
Last edited by Dave A; 20-Apr-24 at 12:46 PM. Reason: tried to improve explanation
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Brilliant Dave.
You are quite correct.
If the test button is connected to the live on supply side, and neutral on the load side of the elr then no current is going to flow through either sensing coil if there's a neutral earth fault because there's an earth bypass.
Now the next move is to open and reverse engineer an Onesto earth leakage to check the connections inside. I suspect that the test button is as you suggested and not as per the diagram I posted. If that is the case, I would suggest that that's a design fault on the unit itself considering the fact that neutrals are earthed on the supply.
Good observation there, Dave.
No need for destruction testing. Just swop the poles and test that way
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👍👍 or use a multimeter and check the reistance whilst pressing the button. 😂😂
Confirmed.
Only one way to open an earth leakage and thats with the tool that has a yellow handle
The 5k1 resistor is connected between live on supply and neutral on load side through the pushbutton.
Now it makes sense. Also checked the plug tester introduces a resistor between live and earth. That also explains why the plug tester wouldn't trip the unit neither.
So the diagram that I pulled off the internet, showing the internal wiring of the pushbutton and resistor is not accurate.
Thanks Dave.
At least I don't have to keep on wondering what was happening.
Hello everyone.
I have a problem at my brother house with the earth leakage or a plug socket that trips the earth leakage.
I did test with plug tester to check if plug is faulty like wire whise, but everything is fine. And the earth leakage is rate 20mA. I test with plug tester it trips on 20mA.
After that I did some other tests
The problem is if I swith of the plug socket the earth leakage trips. I thought it was the outside light then I saw it didn't trip. Then I thought maybe it is the washing machine cause the out side light and washing machine is on a multi plug by this one plug. So I unplug the washing machine and after 3 times to switch off the plug without any load or plug in the socket, it still trips if I swith off the plug.
It is definitely not the plug cause I tried another plug. After switching it off, it trips.
Do anyone know what can cause that.
I would put it down to a loose neutral/swopped neutral and live somewhere in the circuit - Can think of no definite answer for my logic just a gut feel.
I would change the earth leakage relay.
The fact that it's rated at 20mA tells a story. It's probably a Heinemann and on it's way out in any case.
Those units also tend to trip when the power comes back on after loadshedding.
Personally, I would first replace the unit with one rated at 30mA and if the problem persists then start looking for a fault.
Turning a socket outlet on and off without anything plugged into it should not affect the earth leakage relay at all.
Good luck.
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