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Topic Title: To be an RCD brd or not to be!
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Created On: 21 September 2012 01:48 PM
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 02 October 2012 08:31 PM
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spinlondon

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Originally posted by: weirdbeard
Originally posted by: spinlondon
Yes I would mind.

Thats unlike you spinlondon, you are usually fairly tenacious in defence your own interpretations.

It's your concept, you explain it.

You are wrong!


It's not my interpretation.
If it's not your concempt, then who's is it?
 02 October 2012 08:39 PM
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weirdbeard

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spin, take some time and compose yourself before replying, my last reply i had to reconfigure as you deleted then reposted, then you have done the same again with this one, anyone viewing might think you are struggling!
 02 October 2012 08:56 PM
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spinlondon

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I am struggling, struggling to try and understand what you are trying to say.
The reason why I deleted then re-posted, is because the first post had no direct link to your post as it was on a new page.
I deleted then quoted your post to maintain continuity.
 02 October 2012 09:03 PM
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weirdbeard

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Are you done yet changing your posts? no point in me typing another reply to a quote that doesnt exist, then gets rejected and lost in the ether.
 02 October 2012 09:04 PM
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weirdbeard

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Originally posted by: spinlondon

I am struggling,


Yes you are!
 02 October 2012 09:35 PM
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AJJewsbury

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The Regulations require that socket-outlets for use by ordinary persons and that are intended for general use should be provided with 30mA RCD protection.
A designer may specify that all socket-outlets should be provided with 30mA RCD protection, irrespective of whether they are to be used by ordinary persons and irrespective of whether they are to be used for a specific item of equipment or general use.
If you then came along and removed the RCD protection for those socket-outlets, because none of the users are ordinary persons, would you be impairing the safety?
Would the installation still comply with BS7671?

Presuming I'm altering an existing installation here (rather than being the initial constructor ignoring the design), then there could be circumstances where that would be a perfectly reasonable thing to do - e.g. change of tenant from perhaps a childcare nursery to an office with extensive IT equipment; so not the sort of thing I'd expect the regs to put an blanket ban on. I would of course be taking on the role of designer in that case, and should be free (within the constraints of BS 7671) to modify the design/installation as I see fit for the circumstances.

(If I were the constructor for a new installation, I'd be failing to follow the design, for which I would say I would be culpable (although I do notice that the constructor's sign-off on the EIC only declares conformity to BS 7671, and not to the design, which seems a bit odd to me)

- Andy.
 02 October 2012 10:02 PM
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spinlondon

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Do you actually have a point weirdbeard, or are you just going to continue to make inane comments?
You may find it acceptable on the scrwfix forum, but here we expect a more mature attitude.

Andy whilst it may be perfectly reasonable, the fact remains that BS7671 prohibits you from making an alteration which inhibits the safety of the installation.
Now unless you are stating that providing additional protection by means of a 30mA RCD, is not an improvement for safety, then removing the RCD must be an impairment.
 02 October 2012 10:21 PM
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weirdbeard

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Originally posted by: spinlondon

Do you actually have a point weirdbeard, or are you just going to continue to make inane comments?

You may find it acceptable on the scrwfix forum, but here we expect a more mature attitude.



Andy whilst it may be perfectly reasonable, the fact remains that BS7671 prohibits you from making an alteration which inhibits the safety of the installation.

Now unless you are stating that providing additional protection by means of a 30mA RCD, is not an improvement for safety, then removing the RCD must be an impairment.


Phew, glad I left a settling period for you to change your post otherwise that would been another waste of my time quoting your original post, only for it to be lost thanks to your failure to not think through your reply.

You are swimming against the tide!


I'm done.
 02 October 2012 10:38 PM
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AJJewsbury

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Andy whilst it may be perfectly reasonable, the fact remains that BS7671 prohibits you from making an alteration which inhibits the safety of the installation.

So you agree that your interpretation would mean that the reasonable would be prohibited?

- Andy.
 02 October 2012 11:15 PM
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spinlondon

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So rather than waste your time quoting my posts, you'd prefer wasting your time making nonsensical posts.
Ok, is there any chance that you'll actually get around to saying anything meaningful?
What exactly is this tide I'm swimming against, the tide of your inane and tedious posts perhaps?
You obviously believe that something that I have posted on the screwfix forum contradicts something that I've said on this thread.
You are mistaken.
On this thread I am stating that altering an installation so that a single device protects multiple circuits where prior to the alteration, the circuits had individual protection does not minimise inconvenience, in fact it increases inconvenience.
On the thread on the screwfix forum I said exactly the same as I have said in previous posts on this forum; that the Regulations require the whole circuit to be provided for circuits of locations containing baths or showers.
That extending an existing circuit and just providing RCD protection for the extended part of the circuit does not meet with the requirements of the Regulations.
Some have argued that by using an RCD FCU, a new circuit is being made becuase the RCD FCU satisfies the definition as an overcurrent protective device.
Whilst I agree that yes it does meet the definition of a circuit protective device, BS7671 prohibits it from being one.
Regulation 314..4 Requires: "Where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board."
Some people have argued that the RCD FCU satisfies the definition of a distribution board.
Again it may well do so, however BS7671 requires that equipment should meet the British Standard that applies.
An RCD FCU does not meet the British Standard for a distribution board.
As such an RCD FCU is not acceptable as a method to provide 30mA RCD protection for circuits of locations containg baths or showers.
Finally, the manufacturer's instructions for RCD FCUs indicate that they are not suitable for protction of fixed wiring.
Regulation 510.3 Requires: "Every item of equipment shall be selected and erected so as to allow compliance with the regulations stated in this chapter and the relevant regulations in other parts of BS7671 and shall take account of manufacturers' instructions."

I hope this explanaition will help you with your confusion.
 02 October 2012 11:27 PM
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spinlondon

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Originally posted by: AJJewsbury
Andy whilst it may be perfectly reasonable, the fact remains that BS7671 prohibits you from making an alteration which inhibits the safety of the installation.

So you agree that your interpretation would mean that the reasonable would be prohibited?

- Andy.


Andy do you agree that however reasonable your actions may be, they would result in an impairment of safety?

Edited: 08 October 2012 at 12:50 PM by spinlondon
 02 October 2012 11:38 PM
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weirdbeard

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Originally posted by: Rum1


Also i personally wouldn't want to put an RCD main switch only board in - one trip you lose all power - not ideal for any customer really.....


Hi rum1, what about if the cause of the one trip saved someones life, wouldn't you be glad you'd installed it, rather than not because the customer couldn't afford an rcbo board at the time?
 02 October 2012 11:44 PM
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spinlondon

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Conversly, how would you feel if that one trip caused a fatality?
 02 October 2012 11:52 PM
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weirdbeard

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Hi spin, I did say I was done, and I have now officially run out of forum fuel ie. cider so am off tonight, but examine the fundamental principals if you will, how can an electrician be blamed for a fatality where there is no electric? unless we go back to my earlier reference of 131.7 which you poo- pooed. Pip pip.
 03 October 2012 12:34 AM
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spinlondon

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Because the electrician did not divide the installation into circuits so as to avoid danger.
Go back to the earlier reference to 131.7 if you must.
Still waiting for you to explain how a Regulation regarding supply interuptions, relates to division of an installation
 03 October 2012 12:57 AM
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Legh

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Originally posted by: spinlondon

Originally posted by: AJJewsbury

Andy whilst it may be perfectly reasonable, the fact remains that BS7671 prohibits you from making an alteration which inhibits the safety of the installation.


So you agree that your interpretation would mean that the reasonable would be prohibited?

- Andy.


Andy do agree that however reasonable your actions may be, they would result in an impairment of safety?


What about an alteration, where there was a change of usage, such as a medium sized IT warehouse center, to an industrial engineering workshop where there was excessively high earth leakages on various machines, robots and the like requiring a ban of all RCDs/RCBOs and rely on high integrity earthing with supplementary bonding as the main method of shock protection, and so rely on overcurrent protective devices for earth fault protection. (although you might have to change a lot more to provide an IT system with insulation and earth monitoring )

Impairment of safety would then have to be judged against purpose of installation. It might prove to be unsafe to have a RCD/RCBO trip whilst in the process of machining where interlock barriers were used to prohibit access and sudden reenegization through the resetting of a sensitive RCD might cause danger.

Just to add......
On the thread on the screwfix forum I said exactly the same as I have said in previous posts on this forum; that the Regulations require the whole circuit to be provided for circuits of locations containing baths or showers. That extending an existing circuit and just providing RCD protection for the extended part of the circuit does not meet with the requirements of the Regulations.



I'll let the ESC provide an answer
(Copy/paste from ESC web site on alterations and additions)

"Q2. When an electrical appliance such as a boiler or electric towel rail is to be installed in a bathroom where there is no supplementary bonding, and the consumer unit has rewireable fuses and no RCD protection, how can the installer comply with the 17th Edition?

If an existing circuit of a location containing a bath or shower is extended, at least the extended part of the existing circuit must be provided with RCD protection. Supplementary bonding in a bathroom or shower room must be provided unless all the requirements in the 17th Edition for the omission of supplementary bonding are met.

Regulation number(s) 701.411.3.3 701.415.2
"

I think Spin that you have to accept the fact that one sized glove will not fit all sized hands, or was it something else? ........D

legh

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Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 03 October 2012 02:00 AM
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spinlondon

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Yes Legh it may well be that protecting the circuit with an RCD could be less safe than not protecting the circuit.
I assume that is why it is a requirement that safety should not be impaired.
However that does not appear to be the situation in the OP's case.
The OP has made an alteration which on the one hand doesn't comply with Section 314, and on the other hand has impaired the safety of the installation.
Unfortunately the advice given by the ESC is rather contradictory.
For instance there is another question:
Q16. If we reposition a pull switch in a location containing a bath or shower, would the circuit need to be RCD-protected?
Yes, because the work would be more than a like-for-like replacement.
Regulation number(s) 701.411.3.3.
There is no mention that any of the wiring has been altered, extended or shortened, just that the switch has been repositioned. Perhaps because the original fixings have become loose, perhaps because the door has been re-hung so that it opens on the other jamb or perhaps another reason entirely?
So according to the ESC/NICEIC, where a circuit is extended, only the extended part requires RCD protection. However where a circuit is not extended and just a switch is repositioned all of the circuit requires RCD protection.
Further In the ESC BPG for EICRs they do do not consider the lack of RCD protection for circuits of a location containing a bath or shower to warrant any code at all.
If we accept their advice, then it would appear there was no reason whatsoever for the OP to provide RCD protection, let alone by use of an upfront device.
 07 October 2012 09:05 PM
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weirdbeard

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Originally posted by: spinlondon


Further In the ESC BPG for EICRs they do do not consider the lack of RCD protection for circuits of a location containing a bath or shower to warrant any code at all.

If we accept their advice, then it would appear there was no reason whatsoever for the OP to provide RCD protection, let alone by use of an upfront device.


The ESC advice relates to the reporting of the condition of an installation, No harm in actually making an existing installation a bit safer, is there?
 07 October 2012 10:46 PM
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spinlondon

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Your point weirdbeard?
 08 October 2012 10:20 AM
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AJJewsbury

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Andy do agree that however reasonable your actions may be, they would result in an impairment of safety?

I prefer the interpretation: If the results still comply with BS 7671, then it's deemed to be "safe" - if it's "safe" then its safety isn't impaired.

Like I said at the beginning, the simplistic interpretation of the words out of context rapidly leads to such absurdity that it doesn't seem plausible that that was the authors' intention.

- Andy.
IET » Wiring and the regulations » To be an RCD brd or not to be!

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