ELCB-v and readings with earth loop meter

[JohnW2]

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.

I've just blown the dust off an old 60A Crabtree VOELCB whiich has been lying in my cellar for a decade or three. Its coil ('E' to 'F' terminals) measures as about 510Ω (DC measurement). Although the trip voltage is stated as 50V, it actually trips at between 30V and 35V.

Kind Regards, John.

 

[ericmark]

Thanks that then explains all my readings. I suspected that would be likely reason for the high reading.

Good to know as in future if I get reading of that region I know what to look for. Clearly the people who wired in the RCD after the ELCB-v could have never tested the circuits after fitting.

Thanks also to Lectrician on information as to linking sites. The whole web site is at the moment being talked about a lot. Seems the guys who have been writing it for him use Dream Weaver and unless it has a template they will not consider placing pictures in the text. He was told be could not do web sites as one would do in word with text wrapping the picture.

I am uncertain if this is because of time restrictions or some other reason. I have not written a web site in years. As I revisited the idea of writing web sites I see it has come on leaps and bounds since when I started and getting my head around Java is not been easy.

One attempt as a test is here I have realised some of my errors using pictures which were too big for example but to reduce each image is very time consuming and I will guess that's why the guys doing his web site have not used Java except with automatic programs like svBuilder which means one has very few options as to how to lay it all out.

I have been cursing the automatic bits of both Dream Weaver and Front Page when pages have failed I often find the programs have added bits without me seeing it and caused it to fail. Slowly coming to think Notepad is best program! I don't have a clue how many hits I get but always link to his site and his site has been getting more hits since I started to play so it would seem people and finding my site then moving to his.

My hobby is photography and I find myself spending more and more time in his wood. I was thinking I had done well getting fox never mind getting the fox to take pictures.

 

[martinxxxxxx]

Ericmark I had all the same issues with those programs as you and I now use an online program whichis free and has (really has) hundreds of templates it is called http://wordpress.org/

Try it, I think if you used it you would b e impressed

 

[bernardgreen]

Its coil ('E' to 'F' terminals) measures as about 510Ω (DC measurement).

I will offer 495 Ohms at DC. Trip voltage not known, AC impedance not known. ( from old notes )

 

[JohnW2]

Thanks that then explains all my readings. I suspected that would be likely reason for the high reading. Good to know as in future if I get reading of that region I know what to look for. Clearly the people who wired in the RCD after the ELCB-v could have never tested the circuits after fitting.

...or, more to the point, that they had no understanding of VOELCBs, so did not realise that, even if it were maintained as an isolator (a practice I would regard as not very good), they should at least have removed its sense coil from the earth path of the installation.

As for testing, that's a bit more interesting. If they had measured the earth rod or Ze directly (in isolation from installation), they would presumably have got an answer appropriate for a TT earth electrode. As for Zs measurements throughout the installation, they would have been 'hundreds of ohms', but not necessarily 'non-compliant'. Even with a 100mA RCD, 0.2sec disconnection time for 'L-E' faults can be achieved with a Zs of around 1,150&#937; (at 200mA current) . In terms of the 'additional protection' provided by any 30 mA RCDs in the installation, that requires only a Zs <1,667&#937; to achieve RCD operation with a 'touch voltage' of 50V.

Kind Regards, John.