ELCB-v and readings with earth loop meter

[ericmark]

Clearly the old ELCB-v needs changing but out of interest would like to know if this is normal.

Realising that often the old ELCB-v is left just as an isolator and with a RCD 30ma also in circuit I took up my loop impedance meter just to make sure.

Red light came on do not test however knew clear of humans so tried anyway and really high reading. Owner was certain there was an earth rod so hunted and found it. Loop impedance 35 ohms.

So is it the ELCB-v which is causing the high reading? Never had a loop impedance tester when I last worked with them and wonder what the resistance of the ELCB-v is.

Clearly I need to install an earth rod and a new RCD for the parts not covered by existing one. Also need to renew bare copper earth wire for thicker insulated one.

I have every intention of leaving the ELCB-v in place as an isolator but just interested what reading would one normally get when testing a socket protected by a ELCB-v?

 

[ban-all-sheds]

So is it the ELCB-v which is causing the high reading?

Bypass it and see.

 

[RF Lighting]

How high was your really high Zs reading?

 

[ericmark]

Around the 800 ohms mark. It was different each time I tried clearly a problem. I looked at location of consumer unit and considered options and with my mauled hand I had to realise I just could not consider working in that confined space. It was also dark so needed a touch to see anything even at midday.

With my disability only option is to reposition consumer unit where I can work on it lucky all cables out go in same direction and surface so not really a problem.

I have never tested a ELCB-v with a loop impedance tester and so have no idea as to if the high reading is due to internal resistance of the unit or some unseen fault. I am wary of doing anything which could bypass the unit so rendering it inoperative so it's a all or nothing situation can't do anything until I have new consumer unit then power off until all done.

Clearly the guy need power so can't just turn off until complete but never the less it worries me in the mean time. Test button on RCD works but as it if a real fault would trip it not sure. I only took earth loop impedance tester not the RCD tester it's about a mile from road through private wood so everything is on my back. If it will not fit ruck sack then can't carry unless he meets me with tractor.

Really an idyllic location until one needs to do some work. This is his web site http://www.naturalforestpractice.com/index.htm and he is in the middle of this wood not the best of locations to carry all ones tools. Not even allowed to walk up centre of drive have to walk in the vehicle ruts because of special plants growing.

The guy seems more worried about electrocuting resident stoat then himself and any danger to badgers well I would have to run away fast. Nothing like working under the watchful eye of the fox.

As to knocking in an earth rod I am still not sure how I will fair against the tree roots. Hence why not tested to my normal standard there is nothing normal when working on this house. If one can call it a house more a collection of garden sheds.

 

[RF Lighting]

If your Ze is 35Ω, why do you need to install an additional rod?

I think next thing to do is take your RCD tester and make sure the RCD definitely works. If not swap it out for a new one. If you were able to carry out high current loop testing without it tripping then it's probably not working properly anyway.

Then remove the earths from the ELCB and joint them through. It'll render the ELCB useless other than as a main switch, but it sounds like it's doing more harm than good left as it is.

Then you can re-test your Zs and hopefully the figure should have dropped to a much better reading.

 

[ban-all-sheds]

I am wary of doing anything which could bypass the unit so rendering it inoperative

It's no longer doing anything except being an isolator, you said.

Not even allowed to walk up centre of drive have to walk in the vehicle ruts because of special plants growing.

Blow that for a game of soldiers.

The guy seems more worried about electrocuting resident stoat then himself and any danger to badgers well I would have to run away fast.

Neither stoats nor badgers are known to attack humans.

And if you can outrun a stoat get yourself down to Stratford, pronto - your country needs you.

Nothing like working under the watchful eye of the fox.

Yup - they are out there watching you, and it's neither Sam nor Megan.

 

[ericmark]

Fantastic photos. Wish they were mine. I will be returning and correcting things once he has cleared the assess and got parts required.

It is a collection of around 5 large garden sheds some nearly joining each other others quite a way apart and the whole idea of one earth rod for the lot does not really make sense. I will be using at least two.

The earth wires are too small and bare copper so will need replacing and I can't find the earth rod. But all this is nothing really to do with question I just never had a loop tester in the days of ELCB-v's so I have never tried to test the earth loop where one is installed. I will use it as isolator but at moment still active and just pure interest what was the normal result when taking a earth loop impedance reading when a ELCB-v was installed. Has something burnt out inside it or was it normally a high reading?

 

[martinxxxxxx]

It was also dark so needed a touch to see anything even at midday.

I got one of -these recently They are a bit pricy but for working in dark places with the power off, it is the best thing since sliced bread

 

[martinxxxxxx]

Neither stoats nor badgers are known to attack humans.

You sure

 

[martinxxxxxx]

I have tested two sites with these and from memory the readings were normal

 

[JohnW2]

Around the 800 ohms mark. .

That sounds a little high but, if the VOECLB is still 'in circuit' (i.e in the earth path), it sounds like roughly the right ball park- weren't the coils of such things usually in the 300Ω - 500Ω range?

Kind Regards, John.

 

[RF Lighting]

I've got an old ELCB in the back of the garage somewhere. If I remember tomorrow, I'll power it up and do a few tests on it.

 

[martinxxxxxx]

I've got an old ELCB in the back of the garage somewhere. If I remember tomorrow, I'll power it up and do a few tests on it.

You are a Star

 

[RF Lighting]

I'm an electrical geek more like

 

[Lectrician]

Eric - You link to his site, which is great. If he looks at his websites stats (as many people do these days as hosting companies have made it far easier, and more graphical/user friendly), he is going to see a good few 'referrals' from "//www.diynot.com/forums/electrics/elcb-v-and-readings-with-earth-loop-meter.332345/", click the link to see why he has visitors from that site, and see your post


Oh - And I would loose the ELCB, connect the existing rod, or install new, and verify the RCD's operation. I prefer them gone rather than leaving them as main isolators.

I came across a crabtree voltage operated ELCB which had been converted (by manufacturers) into an RCD - pic to follow....

Notice the actually trip mechanism is the old Crabtree ELCB (voltage operated type) with the two terminals at the bottom, one usually connected to the earth rod, and the other to the installations MET.

They have used the two terminals to sense a voltage induced by the 'sence' coil wound onto the main coil.

Still working! Although no mA rating is visible anywhere, it behaved very well at 300mA.