Electric Shock with RCD

Oct 18, 2003 26 Replies

Today I experienced an electric shock in my house, after I touched a bare cable, which I had foolishly left exposed. The cable touched my leg and I had a heck of a jolt up my body which pushed me out of the way.



I am now wondering why the RCD did not trip. Last year a contactum split load CU was fitted, the cable which I touched is on the RCD side. Could there be a problem somewhere, or was the shock I had below the trip current?



Any ideas?



Thanks



Andrew


I'd expect that the shock was probably less than the trip current. If that's a

100mA RCD then it's hardly surprising. However, if you're worried re the RCD then best to get it tested. I assume that you have the test records from the installation which show that it was working when installed?

Also, you should take more care! Shouldn't really have exposed live conductors around to touch and circuits should be isolated (and discharged) before working on them.

J

that's a 100mA RCD then

assume that you have the

conductors around to touch

Yep !!! This one was your warning, the next one might be worse if you carry on exposing live cables in easy reach. Always a good idea, especially if you're going to work on cables that will become live when your testing others that are connected, is to wrap a piece of insulting tape around them before you make the circuits live again for your test.

You don't say what exactly you touched. If you contacted bare live and neutral, then the RCD "sees" you as a normal and legitimate load, and will not trip. This will only happen if current from either live or neutral finds an abnormal return path, normally via an earth.

Charles Fearnley

Perhaps the old description 'Earth leakage' was more informative than 'Residual Current'

"Chris Oates" wrote in news:3f926112$0$6621$ snipped-for-privacy@news.dial.pipex.com:

I think you're right, but the great and the good prolly thought we wouldn't get the idea and try to connect it across earth.

Like Swiss bankers couldn't understand Lsd, so we had to go metric :-(

mike r

Heh, not heard that one before.

Regards, NT

LOL !!!

Oops !!! Insulating tape would be more appropriate, wouldn't it ? :-))

No, I'll be calling it insulting tape now :) Good one.

Regards, NT

LOL! Is that the pink stuff[1] some Lawyers use to tie up their briefs?

Probably would be I think.

[1] Like Red Tape but rather more effeminate!

Take Care, Gnube {too thick for linux}

In article , mike ring writes

Earth leakage trips are not the same as residual current trips. The principle of operation is very different (although the terms are sometimes, incorrectly, used interchangeably)

Earth Leakage Circuit Breaker is generic and covers both types.

RCD is a Current Operated ELCB, whereas the older ones which monitor the voltage on the CPC verses a ground spike are, unsurprisingly, called Voltage Operated ELCB's.

The term RCD resulted from Which? and That's Life! suggesting that the industry adopt a common term, and it needed to be shorter than "Current Operated ELCB" which Joe Public wouldn't understand.

In article , Andrew Gabriel writes

An interesting bit of history which I didn't know (Esther Rantzen's contribution to electrical engineering. Who would have thought it)

"Tim Mitchell" wrote | >The term RCD resulted from Which? and That's Life! suggesting | >that the industry adopt a common term, and it needed to be shorter | >than "Current Operated ELCB" which Joe Public wouldn't understand.

I've never really understood what RCD actually means. I know what they do and how to use them, but Earth Leakage Circuit Breaker does exactly what it says on the BS EN IP-rated enclosure.

| An interesting bit of history which I didn't know (Esther Rantzen's | contribution to electrical engineering. Who would have thought it)

Well, she did play a major part in getting open-flued gas heaters (the infamous Ascot water heaters, my parents always rather liked theirs when they had one) banned in bathrooms because of the dangers of CO poisoning.

Owain

I guess inbetween Esther Rantzen on the one hand, and the nomenclature police at IEE ("extraneous-exposed-conductive-part" - I ask you!) they came up with this neutral no-name thang. "Differential" rather than "residual" might've been a little clearer. "Current Balance Device" would've been informative, *and* used shorter words. Ah well... no-one asked me, right? ;-)

Stefek

Stefek Zaba | the nomenclature police at IEE ("extraneous-exposed-conductive-part" | - I ask you!)

I have a sneaky suspicioun they are trying to harmonise us with something German. More bleedin' hyphens than a Twistleton-FFyffe.

Could have been worse I suppose. Microsoft might have given us "My Grounded Metal Thing".

Owain

No such thing! There are extraneous-conductive-parts [1] and there are exposed-conductive-parts [2]. These are different things, but the twain _should_ meet in your bathroom, via ... (you know the rest).

[1] Non-electrical metalwork which may "introduce a potential, generally earth..." - e.g. metal plumbing & waste pipes. [2] Earthed metalwork of electrical appliances - e.g. wall heater, electric towel rail.

Aye, I do know: and the mumpty that decided on the nomenclature, using two such similar words, deserves to spend a few thousand years in purgatory trapped in a late-1980s helpdesk dealing with Expanded vs Extended memory (come on now! quickly! summarise the differences!) ;-)

Stefek

Good point. Quad & Quattro LNB's provide another example in similar vein.

Reminds me of a news item a few years ago about a flasher who weirded out one too many times. The lady involved had a dog apparently, and the dog decided the exposed parts were extraneous, and did something about it.... eek!

Regards, NT

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