Hi all
Just a little video as promised ( a man of my word ) made on 4th Feb 2020 showing that an earth leakage relay does not trip on a neutral earth fault without a load connected.
Please forgive the filming quality. I am an electrician and not a film maker.
https://www.youtube.com/watch?v=jxG3KFppbZc
Peace out .. Derek.
ians (17-Oct-20)
Er. And?
Help me if I'm wrong guys but dis is not a problem because there will be no current on the neutral wire and when a second appliances(load) is connected it will cause the RCD to trip.
I made this video in response to a number of active forum users who were / are under the impression that all earth leakage relays will trip on an earth to neutral fault even with no load connected. Not so.Originally Posted by skatingsparks
Peace out .. Derek
Exactly.
Peace out .. Derek
I am curious to figue out why my earth leakage unit trips when I perform a similar test ...but Dereks unit doesnt.
I need to figue how a 14 mA leakage current is displayed on the leakge current tester prior to it tripping without a load connected ... in fact both the test earth leakage and the unit in my sub DB trips shortly after the test bench unit trips ... i am going to bypass my Sub DB earth leakage unit
John Ward explains in in a really simple manner ... as i have mentioned ... I understand that a leakage current of around 20-30mA or an unbalance between the live and neutral is required to trip the unit ... but what i dont understand is why my unit trips on the work bench ... what is creating the 14 mA displayed on my leakage current tester ... if no load is connected (ideal situation).
in 99.9 % of the cases where the earth leakage has tripped when i touch the neutral ... the earht leakage has always been connected in a DB ... never a test bench situation ... when i carried out the test on my workbench I was hoping it wouldnt trip ... the only difference betwee nmy test and Derecks test ... I didnt use a plug and plug top ... i just touched a piece of wire between earth and neutral.
https://www.youtube.com/watch?v=JTku...annel=JohnWard
Comments are based on opinion...not always facts....that's why people use an alias.
Hi Ian
I haven't looked at the video, but thinking about a possibility:
In an electrical circuit with a solid grounded neutral or star point the earth and neutral must be at the same potential. The voltage / potential difference between a live and neutral conductor must be exactly the same a the voltage measured between a live and ground conductor. And the voltage measured between neutral and earth should be 0 V.
But in practical circumstances this is not always the case. So if the voltage difference between Neatral and Earth is sufficient to allow the Earth Leakage to detect a current flow of its rated current it will trip when you connect the earth and neutral down stream of the Earth Leakage device without any current flowing in the live conductor / or have a load connected.
I suspect that you have a potential difference between Neutral and Earth on your incoming side, which causes a current to flow from the Neutral to Earth through the ELU when you short them out. It sees this imbalance of current and trips.
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I decided to do a few tests to see why any earth leakage I test in my workshop when I touch neutral to earth ... it trips the earth leakage unit.
Did the same setup as above ... connected the plug to the light circuit for the test(not on earth leakage) everytime i did the test both the test unit and the earth leakage in the DB tripped.
The readings vary slightly.
L-N=229.2 VAC
L-E=230.6 VAC
E-N=2.1 VAC
Hooked the leakage current clamp to the neutral wire ... press the test button ... display 3.6 mA
hooked the leakage clamp around the live ... press the test button ... display 5.9mA
I had the fluke 1653 plugged into the socket of the load side of the test unit ...
press the test button on the fluke meter ... the test unit trips in 16.3 mS
reset and press test button ... the test unit trips at 21mA
Remove the fluke plug top ... to make sure there was no load.
I carried out numerous earth to neutral touch tests ... every single time it tripped the earth leakage unit ... the display on the current leakage tester for each test ranged from ...
9.3mA
12mA
60 mA
95 mA
How do you create a 95 mA fault current with no load connected ?
The unit I used for the tests ...CLipsal 4 RCBM 216/30 10 kA
I connected my site earth leakage rig ... it is an EPC elpro 2 with 4 plugs fluch mounted to the sides of the enclosure ... to my horror ...it didnt trip when i touched the earth to neutral ... I then pressed the test button it didnt trip ... so i plugged in the fluke meter and tested ... it didnt trip ... Good thing i did the test ... I need to replace the earth leakage.. it is 20 years old and had a rough life ... no surprise it failed.
So in conclusion ... if i hadnt seen the video derek posted ... I personally would not have believed it was possible ... you live and learn.
38 years as a hands on construction/maintenance electrician in and around KZN ... I have personally never had an earth leakage unit not trip when i touched the earth to neutral .. unless it was faulty.
It would be interesting to see test results from sparkies in othe rparts of the country.
Comments are based on opinion...not always facts....that's why people use an alias.
Reading through some of the other comments I decided to try something ...
I decided to bridge the neutral and earth at the top of the earth leakage unit ...bingo ... the leakage current clamp display ... eeeish ... 305 mA.
With an earth wire bridged to the top of the earth leakage unit neutral terminal ... touched the an earth wire on the neutral at the bottom of the earth leakage unit ... instant trip.
Comments are based on opinion...not always facts....that's why people use an alias.
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