Earth Leakage problem

[J.Spark]

Hi....I am new here and have a question/problem with an earth leakage tripping.

This problem has me stumped and if anyone can help me it would be great.

A client called me out for an earth leakage tripping. Was going to do the normal test to isolate the problem but then noticed that almost all the breakers are making it trip. To cut a long story short I ended up replacing the earth leakage unit and the same thing happens. The strange thing is that this earth leakage trips on breakers which are not even wired through the earth leakage. Also it trips even when there is absolutely no power on the earth leakage.

Any ideas anyone as I am out of options here.

 

[telectrix]

Neutral in wrong terminal block? visual inspection followed by IR testing.

 

[J.Spark]

Hi....this distribution board hasn't been touched in 5years. All wiring and neutrals are where they are supposed to be and has been working with no tripping for 5 years. 11 circuit breakers out of 20 breakers in the board making it trip. Also when the mains is shut off completely as on no power at all on the unit it trips. IR testing doesn't pick up anything.

 

[J.Spark]

I also tightened every connection in the db. Found a few loose connections which seemed to have stopped the tripping for a bit but then tripped again. Thought I was out of the woods. There seems to be a ghost in this db!

 

[Leesparkykent]

Hi....this distribution board hasn't been touched in 5years. All wiring and neutrals are where they are supposed to be and has been working with no tripping for 5 years. 11 circuit breakers out of 20 breakers in the board making it trip. Also when the mains is shut off completely as on no power at all on the unit it trips. IR testing doesn't pick up anything.

Have you carried out IR testing on every circuit?

 

[J.Spark]

Yes I have and it's all good.

 

[micknew]

We had the same problem on a new build, the tripping was caused by a fault on the overhead DNO supply.

 

[J.Spark]

We had the same problem on a new build, the tripping was caused by a fault on the overhead DNO supply.

Hi....was that with no power on the unit as well? The incoming supply is underground here though. But will check that.

 

[Marvo]

Hi....this distribution board hasn't been touched in 5years. All wiring and neutrals are where they are supposed to be and has been working with no tripping for 5 years. 11 circuit breakers out of 20 breakers in the board making it trip. Also when the mains is shut off completely as on no power at all on the unit it trips. IR testing doesn't pick up anything.

Test for crossed or commoned neutrals (and lives) between all final circuits

 

[J.Spark]

Test for crossed or commoned neutrals (and lives) between all final circuits

Will try that as well. Thanks

 

[HandySparks]

Hi....I am new here and have a question/problem with an earth leakage tripping.

This problem has me stumped and if anyone can help me it would be great.

A client called me out for an earth leakage tripping. Was going to do the normal test to isolate the problem but then noticed that almost all the breakers are making it trip. To cut a long story short I ended up replacing the earth leakage unit and the same thing happens. The strange thing is that this earth leakage trips on breakers which are not even wired through the earth leakage. Also it trips even when there is absolutely no power on the earth leakage.

Any ideas anyone as I am out of options here.

Is the thing that's tripping a differential current RCD or an old style Voltage Operated Earth Leakage Circuit Breaker?

Did you test the sensitivity of the first device before you changed it?

What testing have you done?

 

[J.Spark]

It's a voltage operated earth leakage circuit breaker. Trips out at 30ma as well as the new one. Did the manual testing...visual inspection and IR testing

 

[HandySparks]

It's a voltage operated earth leakage circuit breaker. Trips out at 30ma as well as the new one. Did the manual testing...visual inspection and IR testing

Any chance of a photo of this setup?

 

[J.Spark]

Will have to take the pic tomorrow as I have left site already. Bypassed the unit so long and works fine when bypassed. Will send tomorrow. Thanks

 

[Lucien Nunes]

It's a voltage operated earth leakage circuit breaker

This is important and needed to be stated explicity. VOELCBs can trip as a result of a fault in a nearby property even when the ELCB's own installation is switched off, because they monitor the CPC not the L & N. If there is a difference in potential between the earth electrode and any part of the installation CPC, perhaps at a fitting in casual or deliberate contact with an extraneous pipe, then a current will flow through the tripping coil. Possible causes include a non-protected circuit next door dumping current into a service pipe or the rods being too close together and in each others resistance area.

Conversely, this type of problem cannot affect an RCD as it neither knows nor cares what is going on with CPCs and main earthing conductors.

 

[J.Spark]

This is important and needed to be stated explicity. VOELCBs can trip as a result of a fault in a nearby property even when the ELCB's own installation is switched off, because they monitor the CPC not the L & N. If there is a difference in potential between the earth electrode and any part of the installation CPC, perhaps at a fitting in casual or deliberate contact with an extraneous pipe, then a current will flow through the tripping coil. Possible causes include a non-protected circuit next door dumping current into a service pipe or the rods being too close together and in each others resistance area.

Conversely, this type of problem cannot affect an RCD as it neither knows nor cares what is going on with CPCs and main earthing conductors.

Ok....never came across a problem like this....came across many trippings but not one of this nature. [emoji16]

 

[Octopus]

Yes I have and it's all good.

with all the bulbs out and the lights switched "on", including checking the strappers on 2 way lighting?

 

[J.Spark]

No....didn't do that....will double check on that. Thanks for the advice

 

[Octopus]

Have you got a clamp meter?

 

[J.Spark]

Yes I do

 

[Octopus]

Yes I do

what is the "back ground" leakage like across the installation?

 

[J.Spark]

How does one test for back ground leakage?

 

[Lucien Nunes]

Murdoch dunno if you spotted the bit about the ELCB still tripping with the installation off at the main switch? I think that is what was meant (J.Spark, can you confirm?) in which case I don't think it's leakage from this installation but from elsewhere circulating via the MET. This is one of the rare cases where it's actually helpful to clamp either of the earth leads going through the ELCB, normally clamping a CPC can give misleading results but here it's relevant because that's the current in the trip coil. If it's more than the current measured with the two tails clamped together (this system's leakage) then the problem is external.

 

[Marvo]

In the OP he states he replaced the 'earth leakage unit' with a new one, after I read that I wrote off any possibility it was a VOELCB. Photos would be handy if JSpark can attach a couple..

 

[J.Spark]

Murdoch dunno if you spotted the bit about the ELCB still tripping with the installation off at the main switch? I think that is what was meant (J.Spark, can you confirm?) in which case I don't think it's leakage from this installation but from elsewhere circulating via the MET. This is one of the rare cases where it's actually helpful to clamp either of the earth leads going through the ELCB, normally clamping a CPC can give misleading results but here it's relevant because that's the current in the trip coil. If it's more than the current measured with the two tails clamped together (this system's leakage) then the problem is external.

Yes....still trips with the 3 phase main switch shut off. Tested no voltage to the top of the ELCB....which I find very odd. Cannot wrap my head around that.

 

[J.Spark]

In the OP he states he replaced the 'earth leakage unit' with a new one, after I read that I wrote off any possibility it was a VOELCB. Photos would be handy if JSpark can attach a couple..

Will do so when I am on site again

 

[Lucien Nunes]

An N-E fault can trip a TP+N RCD with the three lines isolated (not all 3-phase main switches isolate the neutral, unlike single phase DP). Current e.g. from a TN-S neutral above earth potential can pass to earth at the fault via the RCD N which the RCD will sense as a residual. Hence, the importance of the IR tests even though the fault doesn't require the system energised to trip.

But, what is this thing we're discussing? RCD? VOELCB? I was taking it to be a VOELCB because you said it was, but now I see Marvo has a point.

 

[J.Spark]

OK....let me rather attach some pics of the ELCB and take it from there. Thanks for the help guys. Appreciate this. Will be in contact during the course of the day tomorrow.

 

[J.Spark]

I am from South Africa so the wording may be a little different lol!

 

[Marvo]

I am from South Africa so the wording may be a little different lol!

Ahh, I've got a feeling your terminology is causing kak boet.

 

[Lucien Nunes]

'n buitelander! Marvo, let vertaal dit vir ons...

 

[J.Spark]

Hahaha haha yeah I am sure lol!

 

[Marvo]

Is it the usual black CBI samite mount earth leakage breaker?

 

[J.Spark]

The din rail type....schneider electric make

 

[Marvo]

Then it's a standard 30mA RCD. Is it being used as the main breaker or is it just supplying the sockets?

The only way it can trip with the installation isolated is if there's power still on it from another source which is unlikely as you said you checked for supply voltage after isolating so something's not adding up.

Note for the UK guys, South African DB's (CU's) generally have all RCD's and MCB's supply at the top and final ccts connected at the bottom and it's common practice for the entire installation to have a single upfront 30mA RCD.

 

[J.Spark]

Yes only for sockets....but I find it strange that it trips like this....even trips with putting on some circuits which are not running through the earth leakage as well as when there is 0 voltage on the top.

 

[Marvo]

Yeah, it's not making sense, an RCD can't trip unless there's power coming from somewhere. Is there an inverter back-up system, solar pv system or UPS in the premises perhaps?

 

[J.Spark]

Nope.....nothing like that....I double checked voltage on top all the time to make sure because this confused me quite a bit. Never came across something like this. Very strange to say the least.

 

[Marvo]

I'd check for voltage on the load side as well. Do all the usual tests like megger test the circuits, test for crossed circuits/borrowed neutrals (continuity between circuits) and a leakage test with an earth leakage clamp meter around the L+N at the RCD.

With the RCD tripping when the power is isolated I'd suggest extreme caution, treat the DB and all circuits as live until you find the cause of that.

 

[J.Spark]

I did check on load side as well. No voltage. But will do all the tests again and double check on all again.....hopefully it has fixed itself overnight lol! One can only wish lol!

 

[Octopus]

Best that the op updates his location to avoid future assumptions

 

[J.Spark]

Morning guys.....these are a few pics of the set up..... top left is the ELCB....

 

[J.Spark]

Last night I bypassed the ELCB so that the client has power hence no wiring in the unit....

 

[J.Spark]

another pic

 

[Lucien Nunes]

If only we'd had the pics to start with. Let's recap:
In South Africa.
3-phase supply to board with TP main switch, unswitched neutral.
Loads (mainly or all single-phase) supplied from SP MCBs.
Supply side of MCBs hand-wired and SP busbar, not ready-made TP busbar.
12 circuits on blue phase fed via DP 30mA RCD, associated neutral bar arrangements not visible.
RCD trips with load on unprotected circuits and sometimes even with main switch off.
IR on all circuits thought to be OK.

VOELCB was a red herring!

 

[Marvo]

^^Yeah deffo not a voltage operated device. The set up above is pretty much standard for large domestic and small commercial, we don't usually use pre-assembled CU's and I'm surprised there's even busbar, usually the MCB's etc just have multiple wire links across the tops of them.

Not sure why it's a 3-phase supply, domestic is usually single phase 60A but wit three geysers it's possibly commercial. The fixed loads such as geyser (immersion heater) and also the outbuilding should be fed by d/pole SP+N MCB's so the DB is not compliant.

JSpark, the board is a bit rough even by our standards but par for the course. Refer to the previous posts, identify the L+N of all the circuits on the RCD and do the tests for insulation and crossover with other circuits. Just be methodical, treat as dangerous until you figure out why the earth leakage is tripping with the main breaker off.

 

[J.Spark]

I forgot to mention that there is a main switch on the energy dispenser unit (as per pic) which serves as the main switch. This one cuts off the neutral as well.

 

[J.Spark]

Yes the board is very shoddy. This DB was wired by some magician 5years ago. Though 3phase set ups are quite common here in domestic installations depending on what the client requires or municipality requires etc etc. You even get some bachelor flats here that have a 3phase incoming supply.....so yes some of the 3phase set ups here are overkill.

 

[J.Spark]

Geez guys....this problem is not cool! Went through the entire DB....neutrals are all where they are supposed to be....lives where they are supposed to be but still when switching off the mains at the energy dispenser which cuts off neutral as well the ELCB still trips. Sometimes it stays on for as long as 5mins and sometimes within a few seconds it trips out. I feel like back pedalling out of here. Driving me insane!

 

[HandySparks]

...but still when switching off the mains at the energy dispenser which cuts off neutral as well the ELCB still trips. Sometimes it stays on for as long as 5mins and sometimes within a few seconds it trips out.

With the supply isolated at the 'energy dispenser' (not a term we're familiar with over here), try measuring the voltages around the offending ELCB: L-N, L-E, N-E, on both supply and load side with the ELCB both closed and open. I'm finding it hard to understand an ELCB (or RCD) tripping without a supply of some sort.