Electrical nightmares

[ians]

Derek there has to be a reason why i can do it and you cant... i just want to know why.

This would be an interesting test for electrician in different provinces... in Durban the earth is supplied from the municipality...if I switch off everything except the main switch and earth leakage unit... take a plug top and short out the neutral and earth pin ...plug it into a socket ...you cannot reset the earth leakage unit if the main switch is switched on.

I would love to hear what the results are from other provinces...maybe in East London they might have a different earthing arrangement... TN-S ...TN-C-S ... TN-C ...I would love to know why i can do it and other people cant... have any other sparkies tried this in East London?

[ians]

I have another concern that has always boggled my brain... customers complain about a tingling feeling when they touch the washing machine ...generally it means the earth wire is not connected ...i find where the earth wire is off and reconnect it... what blows my mind is that there is no more tingling ...but earth leakage doesnt trip ...and i do check that the earth leakage is tripping at around 25 mA and the trip button is working.

[Derlyn]

Quote Originally Posted by From another forum
Short neutral to earth on a circuit carrying a load, and part of the neutral current flows through earth conductor instead of neutral. The ELB sees an imbalance and trips. So an ELB trips on almost any live fault, but only trips on neutral faults if the circuit is carrying a load.

Hi Justloadit

Read the above again. I believe this was posted by you.
Now read the last sentence, especially the second half after the comma.
Can you see that the ELR only trips on a neutral fault under load conditions.

Now why would this be ?

The answer is that only under load conditions is there current flowing through the ELR.

Now you yourself said that the ELR checks the current flowing in the live and the current flowing in the neutral. If these 2 currents differ by either equal to or more than the sensitivity of the unit, it will trip. I agree 100%. BUT What happens when there is ZERO current flowing in the live and neutral ?

For example: Live current 0.000Amps, Neutral current 0.000Amps Difference 0.000Amps ( no tripping I'm afraid )

You can create as many neutral to earth faults as you like, the ELR will not trip as there is no current flowing in either the live or neutral conductor through the unit.

Now some senior contributors have suggested that the ELR will trip on a neutral/earth fault even with the load circuit breakers turned off.
How does one get any current to flow through the ELR with the load circuit breakers turned off ? Where's that current coming from ?

No, it's got nothing to do with the area. TNCS in Durban is TNCS in East London is TNCS in Johannesburg. It's got nothing to do with different provinces as was suggested.

It's got to do with the simple fact that the ELR only trips when the difference in current in the live and neutral through the unit is greater than the unit's sensitivity. If there's no current flowing through the ELR ( no load ) it will not trip even if there are 100 neutral to earth faults.

This is not too difficult to understand.

Still busy with a video and will post it as soon as I know how to.

Cheers and peace out ... Derek

[Justloadit]

Hi Justloadit

Read the above again. I believe this was posted by you.
Now read the last sentence, especially the second half after the comma.
Can you see that the ELR only trips on a neutral fault under load conditions.

Now why would this be ?

The answer is that only under load conditions is there current flowing through the ELR.

Now you yourself said that the ELR checks the current flowing in the live and the current flowing in the neutral. If these 2 currents differ by either equal to or more than the sensitivity of the unit, it will trip. I agree 100%. BUT What happens when there is ZERO current flowing in the live and neutral ?

For example: Live current 0.000Amps, Neutral current 0.000Amps Difference 0.000Amps ( no tripping I'm afraid )

You can create as many neutral to earth faults as you like, the ELR will not trip as there is no current flowing in either the live or neutral conductor through the unit.

Now some senior contributors have suggested that the ELR will trip on a neutral/earth fault even with the load circuit breakers turned off.
How does one get any current to flow through the ELR with the load circuit breakers turned off ? Where's that current coming from ?

No, it's got nothing to do with the area. TNCS in Durban is TNCS in East London is TNCS in Johannesburg. It's got nothing to do with different provinces as was suggested.

It's got to do with the simple fact that the ELR only trips when the difference in current in the live and neutral through the unit is greater than the unit's sensitivity. If there's no current flowing through the ELR ( no load ) it will not trip even if there are 100 neutral to earth faults.

This is not too difficult to understand.

Still busy with a video and will post it as soon as I know how to.

Cheers and peace out ... Derek

I hear what you are saying. I am explaining what I have experienced, ELB trip with no loads connected.
The ELB senses the differential between Live and Neutral, as has been agreed by every one, if there is any current flowing between Neutral from source (Municipal) to Earth at the point of testing, then it stands to reason that there is a differential between Neutral and no current in Live so it trips, so there is no load connected at the DB under test.
It may be that there is an issue with the municipal supply Neutral/Earth that is causing this. As I mentioned before it also may add to the issue being further away from the transformer supply, as there are loads connected before the DB under test. It may be that there is an issue with other DBs connected to the grid which may be causing the issue as well.

The discussion here is to identify, so that we can correct .

[ians]

So i called a man about a dog and he explained to me why it should/will trip when you connect the neutral to the earth.

Derek you are correct in saying that there has to be load/current...it only has to be more than in my case 25 mA... i am very interested to know why your earth leakage is "not" tripping... take a current leakage tester and clamp it around the line and neutral and tell me what the reading is... i am going to bridge out my earth leakage unit and actually test the leakage current when the neutral and earth are connected together.

How it works...by connecting the neutral to earth it creates a small leakage current to earth which will cause the coils around the live and neutral inside the earth leakage unit to be unbalanced which will cause the earth leakage to trip.

[Derlyn]

Hi Ians

Wait for my video.
It's in production.
Then I just need to find out how to post it onto the forum.

Cheers and peace out .... Derek.

PS. If the earth to neutral voltage is 0 Volts, which is the case in most domestic installations because the earth and neutral are connected together in either the prepaid meter or on the neutral bar in older installations, then NO current can flow between the earth and neutral..

[Justloadit]

Hi Ians

Wait for my video.
It's in production.
Then I just need to find out how to post it onto the forum.

Cheers and peace out .... Derek.

PS. If the earth to neutral voltage is 0 Volts, which is the case in most domestic installations because the earth and neutral are connected together in either the prepaid meter or on the neutral bar in older installations, then NO current can flow between the earth and neutral..

What about reverse fault current flow through your ELB?
That is, because you have shorted out the Neutral and the Earth through your DB, it stand to reason that there will be current flowing in the reverse direction from the utility side, through your ELB. The short will have caused a shorter path for the fault current.
You have no control of other loads on the line before your DB.
The ELB can not differentiate the differential fault current created by loads connected before or after the ELB, after all it is AC.
What I am effectively saying is that the ELB may react on effects from the supply side.

A typical example is a lightning strike down the road from your installation, in some cases this causes your ELB to trip. Now why is this, after all the lightning did not strike your installation, but yet the ELB tripped.

[ians]

Hi Ians

Wait for my video.
It's in production.
Then I just need to find out how to post it onto the forum.

Cheers and peace out .... Derek.

PS. If the earth to neutral voltage is 0 Volts, which is the case in most domestic installations because the earth and neutral are connected together in either the prepaid meter or on the neutral bar in older installations, then NO current can flow between the earth and neutral..

Make sure the video includes a leakage current clamp around the live and neutral and and ammeter (mA ) in series with the neutral to show there is no leakage current or current flow to earth.

[ians]

A free tip for all the sparkies who are not familiar with a leakage current tester:

Leakage current tester are expensive (i paid about R4000 for mine many years ago)... however if you take into to consideration how much time is wasted trying to trace earth leakage faults ...this tester is worth every cent.

Where it is extremely valuable... in places where you cannot just bust out an insulation resistance tester and start pumping 500 - 1000 volts into the electrical installation due to various factors.

The easy way to trace earth leakage faults... you just clamp the tester around the live and neutral (not the earth wire) on each circuit as it enters the DB... the bonus about this method is you can actually add up all the leakage current which could also explain why you are experiencing nuisance tripping... or if you have faulty lightning protection plug tops (the red ones ) which might have taken a hit and and is not quite down to earth yet ...but causing random tripping over a period of time... this was the reason i purchased mine a couple years ago.

I got a complaint about an earth leakage unit which was tripping every 2 weeks or so... i stripped the place down...carried out insulation resistance tests on all the circuit ...they were all clear...put everything back together... 2 weeks later i got a call ...same problem... went and purchased a leakage current clamp ...figued out how to use it... went to site clamped it around the live and neutral at the DB ...found the circuit with a high reading... unplugged the computers until the value dropped ... cut the 2 plug tops off which had high reading... replaced them... problem solved.

Lucky they didnt phone Carte Blanche ...i only supplied 2 x plug tops and the bill came to about R20 000.

[Derlyn]

Make sure the video includes a leakage current clamp around the live and neutral and and ammeter (mA ) in series with the neutral to show there is no leakage current or current flow to earth.

Hello my brother

All available literature, as well as my experiences over the last 41 years, suggests that an earth leakage relay will not ( and should not ) trip on a neutral/earth fault if there is no load.

To prove this with a video does not require the use of current clamps and mA meters.

It's gonna be simple, to the point, so that anyone can understand it ..... even the layman.


Cheers and peace out .... Derek


PS. You will have to forgive me but I am not a film maker or editor. I'm an electrician. So when you eventually see the video, please don't critisize my editorial or film making skills as they are non existent.

[Rifrug]

Hello my brother

All available literature, as well as my experiences over the last 41 years, suggests that an earth leakage relay will not ( and should not ) trip on a neutral/earth fault if there is no load.

To prove this with a video does not require the use of current clamps and mA meters.

It's gonna be simple, to the point, so that anyone can understand it ..... even the layman.


Cheers and peace out .... Derek


PS. You will have to forgive me but I am not a film maker or editor. I'm an electrician. So when you eventually see the video, please don't critisize my editorial or film making skills as they are non existent.

Hi Derek, According to me most earth leakages will trip even if circuit breaker is switched off. Have you ever installed a new circuit and the breaker is off, but you tape up the neutral wire when making the final connection because you don’t want to trip the earth leakage. Or even if you cut throug a norsk cable with breaker of it trips 99% of the time.
I would think it is because of of the distance to the Neutral/Earth bond at the transformer. The earth wire has a resistance and the neutral wire has a different resistance now put power on earth leakage and you are creating a load through the capacitance of the cable this might be mA but enough to trip the earth leakage. If the transformer is very close to the earth leakage or there is a neutral/earth bond close-by the capacitance of the wire might not be enough to trip the E.L.

[Derlyn]

Hi Derek, According to me most earth leakages will trip even if circuit breaker is switched off. Have you ever installed a new circuit and the breaker is off, but you tape up the neutral wire when making the final connection because you don’t want to trip the earth leakage. Or even if you cut throug a norsk cable with breaker of it trips 99% of the time.
I would think it is because of of the distance to the Neutral/Earth bond at the transformer. The earth wire has a resistance and the neutral wire has a different resistance now put power on earth leakage and you are creating a load through the capacitance of the cable this might be mA but enough to trip the earth leakage. If the transformer is very close to the earth leakage or there is a neutral/earth bond close-by the capacitance of the wire might not be enough to trip the E.L.

Hello brother.

The reason it trips is because there are other circuits supplied by the earth leakage that are on and the earth leakage is under load.

Turn off ALL the breakers to circuits supplied by the earth leakage relay then you can cut through the cable and the earth leakage will not trip.

A good tip when installing a new circuit is to do all your final connections first and connect the supply and neutral last. That way there's no chance of accidently tripping the earth leakage.

Believe me. Been there, done that.

An interesting watch https://www.youtube.com/watch?v=JTkuoMplER8


Cheers and peace out ... Derek

[ians]

Derek all i am gona say... until i see a leakage current clamp on a circuit ...i am gona rather just stick to what i know and test carried out using the correct test equipment... it sounds like the fella who issued the COC in December last year ...he spent a whole week fixing faults so the COC should be valid... i am saying to him without the correct test results the COC is invalid... when he has to send his teams back to a site to install earth wires from the DB to the junction boxes.. that is a clear indication that his theory that a weeks worth of repairs doesnt make the COC valid...but rather the test results...so lets see the test results and then i will be convinced....until then i stick to my test results.

This explains why Carte Blanche took the fella to task...electricians in Durban are dime a dozen for a s little as R140...The electrical industrial council... the ECA and the DOL are gona have to review their minimum rates.

I wonder if the vibrators are connected to power or battery operated


ZAR140
Registered electrician offering all electrical services industrial, commercial around Durban, & supply electrical equipment [Motors and Vibrators]

https://www.facebook.com/marketplace/item/221290908883835/

[Dave A]

PS. If the earth to neutral voltage is 0 Volts, which is the case in most domestic installations because the earth and neutral are connected together in either the prepaid meter or on the neutral bar in older installations, then NO current can flow between the earth and neutral..

There's the difference right there.

Supplies in Durban are TN-S. I gather from your statement that your supplies in East London are TN-C and the installation is set up as TN-C-S.

Agreed - The first requirement for a neutral-earth fault to trip the earth leakage is a voltage difference between earth and neutral. Without it there's nothing to drive the current.

I went over our last 10 COC's issued. The lowest E-N voltage reading was 0.14 volts. With a typical loop impedance test result of 0.6 ohms, we can expect this to produce a dead short current between earth and neutral of around 233 mAmps. Perhaps more as the transformer's resistance is not going to be a factor.

For the record, the E-N range in that sample of 10 COC's was 0.14 to 0.67 volts with the 0.14 volt instance used above being the only one below 0.3 volts.

[Dave A]

On the flip side who the hell are the ECA to dictate contractors mark-up? That pisses me off almost as much as the cowboy ripping people off using scare tactics.

As indicated previously, I share your sentiment and have followed up on this.

Attached to this post please find the official ECA SA response.

Carte Blanche 19 Jan 2020 ECASA response.pdf