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Topic Title: RCD not tripping on test again!
Topic Summary: Different problem to jzn's so didn't want to tag on
Created On: 15 October 2008 02:39 PM
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 15 October 2008 02:39 PM
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kiwiscouse

Posts: 31
Joined: 05 May 2007

Hi all. Just installed a panel heater in a wc for a friend. TT installation Ze about 1300 and main water bond to earth terminal about 180. So I installed new bond (10mm) and new main to existing stake (16mm). While finishing testing the rcd failed to trip. Showed >500ms on 1x and >400ms on 5x (I assume that's my meters default as I haven't had one fail it before). Now this is an old Crabtree RCD unit external to the 5419/3036 board. I have already stressed that we need to change this and it was a job for the near future. Ofcourse this new problem has brought the job forward and will happen in the next 2 weeks (while they are away at half term).

My question is... Have I made the installation more dangerous by upgrading the earthing as the RCD is useless? Do I need to insist we do it Tomorrow?

Edited: 15 October 2008 at 02:58 PM by kiwiscouse
 15 October 2008 04:09 PM
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rocknroll

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Joined: 03 October 2005

I think what both of you need to do first is remove the load from the RCD and test the RCD only, the RCD test is only meant to test the RCD and not your circuit wiring, once you have established that the RCD is ok then move on in a logical way to diagnose the fault.

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Edited: 15 October 2008 at 05:30 PM by rocknroll
 15 October 2008 04:12 PM
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JZN

Posts: 551
Joined: 16 November 2006

Have you trned off the MCBs and disconnected the neutrals and tested? That way you can be certain it's the RCD and not some sort of fault on a circuit fed from it.

If the RCD is bust then a temporary fix would be to install a stand-alone RCD between the meter and the consumer unit until the unit is upgraded.

John
 15 October 2008 05:06 PM
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kiwiscouse

Posts: 31
Joined: 05 May 2007

Thanks for the replies Gents. I'll certainly test the rcd standalone etc. I geuss I assumed the unit was faulty because it is so old. Any thoughts on how the touch voltage will be affected i.e. better earth so higher current flow on fault but, as you know, it takes a lot more to blow a 3036 than it does to give a serious shock.
 15 October 2008 05:43 PM
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John Peckham

Posts: 7253
Joined: 23 April 2005

What is the BS on the RCD? It is not an old VOELCB to BS 842 by any chance?

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John Peckham

http://www.astutetechnicalservices.co.uk/
 15 October 2008 05:50 PM
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kiwiscouse

Posts: 31
Joined: 05 May 2007

Sorry. Didn't see one. It's old, black, screw on lids top and bottom for tails, yellow test button below switch in middle. And it's Crabtree.

p.s. I'll find that out and report back. Hope it's not written on the back.

Edited: 15 October 2008 at 05:57 PM by kiwiscouse
 15 October 2008 05:59 PM
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rocknroll

Posts: 8808
Joined: 03 October 2005

Thats an old voltage operated circuit breaker and yes it does require replacement and you wont be able to test it either.


regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 15 October 2008 06:20 PM
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daveparry1

Posts: 5888
Joined: 04 July 2007

As rocknroll rightly says this is an old voltage operated elcb and it won't respond to your tester. I know we all have to start somewhere but i'm surprised you didn't know about these if you're getting involved with this type of work!
 15 October 2008 06:31 PM
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rocknroll

Posts: 8808
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A while back someone asked me for a wiring diargram of a VOECLB, so I drew one and added a bit of info with a photo relating to one of these type of circuit breakers, ENJOY

http://uk.msnusers.com/SparkyR...ShowPhoto&PhotoID=130

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 15 October 2008 07:03 PM
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GeoffBlackwell

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Originally posted by: rocknroll

Thats an old voltage operated circuit breaker and yes it does require replacement and you wont be able to test it either.


Well you used to be able to test them. The instrument was really just a transformer with a 40 volt output, and it only checked that they tripped.

The trouble started if there were any other trips close by, because they might trip too .

I remember doing this as a apprentice in a terrace house in Ramsgate. The electrician and I got the tester out of its shiny new box and eventually learned how to use it. All went well till we went out to the van and there were all these people in the street asking one another if their supply had gone off - we made a hasty retreat .

Regards

Geoff Blackwell
 15 October 2008 07:05 PM
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rocknroll

Posts: 8808
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regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 15 October 2008 08:05 PM
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dbullard

Posts: 1166
Joined: 02 March 2006

Not seen one of those for along time brings back fond memories......................those were the days.

No doubt now i will have a string of them and all faulty !!!!!!!!!!


Regards Daren

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..... Dont pee in my pocket and tell me its raining ......


www.quest-electrical-sw.co.uk
 15 October 2008 08:16 PM
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beaver74

Posts: 361
Joined: 07 February 2007

that Ze is way to high for my liking and yes put a r,c,d in asap
 16 October 2008 11:09 AM
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kiwiscouse

Posts: 31
Joined: 05 May 2007

Thanks for all the helpfull replies.

RnR Thanks for the diagram and picture yes mine looks like that but a different brand, slightly shorter caps either end. Just a quick question on your diagram. I can see how the coil trips the switch under fault conditions but not when the button is pressed. It seems the push button breaks the circuit from the coil and just livens the protected metalwork. I am only fairly new to this game (started training April 2002 in NZ got my electrician ticket in january 2006) so shoot me if I'm wrong, willing to learn from more experienced guys (and girls!).

Which brings me to Dave Parry. Thanks. I have to hold my hands up here. I didn't recognise it as I should have. These things were glossed over in my training and testing was not as thorough as it is over here. I thought I'd come across something similar before which was an old RCD, I was obviously wrong. Thought the earth wires were just looped in and out. This is something I will not fail to spot again.

Beaver 20.5 after installing new main earthing conductor. Pretty good for a TT I thought.

Anyway, thanks to all again. Now I'm off to convince them of the need to continue with the work.

Regards
Bob
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