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Topic Title: 411.3.3
Topic Summary: No RCD risk assessment
Created On: 07 February 2015 08:38 AM
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 07 February 2015 04:11 PM
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OMS

Posts: 22359
Joined: 23 March 2004

It may be in the example, Leckie that the employer bans people from bringing thier own kit on site and plugging in.

He tests his own kit reguarly - he give the cleaner a portable RCD or has an RCD plug top on that bit of kit

He doesn't permit general employees to plug things in - he has a competent person to do that, and into labelled sockets

Where now would you Code ?

OMS

-------------------------
Let the wind blow you, across a big floor.
 07 February 2015 04:21 PM
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leckie

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Sorry John, I was going between both AMD2 and 3, and exploring the difference.

What I was trying to get at was that even prior to AMD3, I have always thought there should be a RA in place, and have advised that for years if inspecting an existing installation.

I also thought we were discussing both design and inspection through this thread, not just new installations; well I am anyway
 07 February 2015 04:23 PM
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leckie

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Well that is true OMS, but then there would be a RA or a documented method. I said I was assuming no RA.
 07 February 2015 04:37 PM
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OMS

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There is no RA - just a documented policy

Where next ?

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 07 February 2015 05:39 PM
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leckie

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If, inspecting to AMD2, there was a documented policy, RA, or other such thing, indicating competence or people were instructed, then there would be an exemption.

But I have hardly ever seen one. You would OMS because you deal with proffesionals. Unfortunately, nowadays I am tending to operate at the level of " bloody elf and safety" type attitudes.
 07 February 2015 05:48 PM
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Fm

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Originally posted by: OMS

It may be in the example, Leckie that the employer bans people from bringing thier own kit on site and plugging in.



He tests his own kit reguarly - he give the cleaner a portable RCD or has an RCD plug top on that bit of kit



He doesn't permit general employees to plug things in - he has a competent person to do that, and into labelled sockets



Where now would you Code ?



OMS



Exactly what I do over my building portfolio.
1 step in keeping the ambulance chasers away
 07 February 2015 06:29 PM
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Zs

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Phantom, after your post about (b) I noticed that unlike (a) it doesn't exclude dwellings. The risk assessment bit is for non-dwellings but the labelled outlet includes them.

Glad about that because I have some out there for the fish tank and the freezer when my clients go on holiday.

For the purposes of this question I was thinking about new stuff, so design, initial verification and all that. I'll worry about I&T after July

Then OMS mentions finding a suitable default position...I doubt that the great and the good around that table will have the kind of understanding that some of the complex (and intelligent) clients do. However, I am extremely inclined to ask for risk assessment from the non-dwelling client and not make it up for them. But then my head starts to go round and round yeah but no but yeah but what if the client asks me to help write the RA...am I not exposing myself to a possible future criticism for helping to write it?

Then my head exploded.

Spin, that was my understanding and certainly how I've heard it being discussed by all sorts of blokes down the pub and engineering types, hence my asking. But never seen it written. I was surprised by the wording.

JP, this is important...you said ' The wise council are saying the designer should get the RA from the client at the design stage.' Where are they saying that? That is exactly my question. They are saying that a documented risk assessment exists. Not who creates it.

IronFreely (come round here and iron as much as you want btw), great post. Damned if we do and damned if we don't?

Thank you for helping me to understand that I don't understand.

Zs

Edit.. Alan, no I did not have any input into GN3 this time. I'd not have been able to find the time for it but wasn't invited anyway. It was a great life-experience and I'm proud to have my name in an IET book, but a complete one-off. I look forward to waving it at the nurses from my rocking chair one day.

Edited: 07 February 2015 at 06:46 PM by Zs
 07 February 2015 06:41 PM
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John Peckham

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Zs

The experts on the IET panels at the ELEX shows from NICEIC, Stroma, ECA and NAPIT.

Can you think of a circumstance where the need for a RA canot be designed out at the design stage using my 6 factors in my post above?

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 07 February 2015 06:41 PM
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spinlondon

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These changes in the requirements for RCD protection of sockets, has now placed responsibility for safety, firmly on the shoulders of the designers.
Any designer who now does not specify RCD protection for all socket-outlets will be leaving themselves wide open to litigation for the life of their design.
 07 February 2015 06:50 PM
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Zs

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'The experts on the IET panels at the ELEX shows from NICEIC, Stroma, ECA and NAPIT. '

Oh, I see.

No further comment your honour !

Present company excepted of course....

Zs
 07 February 2015 07:53 PM
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Zs

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Hello JP, Yes I can, for all but one of yours which is the one I recently decided to go for. It is a special case but seeing as you ask and just for the fun of catching up with one of my mentors you understand;

You ready?

Originally posted by: John Peckham

I am going to be even bolder and say I don't think an RA saying 30mA RCD protection should ever be required. I say this for the following reasons.



1. Consideration for the omission of RCD protection is carried out at the design stage.

I am the designer. This is why I am asking. Further, I am considering it. What gives me any right to make such a decision without compliance with Big Yellow....short of a shed-load of ambiguous labels that will probably be refused by the client authorities, I need an RA. From somewhere.



2. The designer has common law and statutory duties to design a safe installation.

In accordance with BS7671 and other statutory and non-statutory licencing agreements. Oh, BS7671 is on the list...slightly stuffs me from not addressing the issue then? Yeah but no but JP...



3. The problem of unwanted RCD tripping can be designed out at the design stage as required in 314.1 and 531.2.4. Having more circuits with less kit connected. Or an unprotected circuit with RCD sockets fitted.

Earth to JP....In most cases yes, but certainly not in all cases. As designers, we have to take the client specifications and work from them. If I have a certain number of TP&N ways and must leave 25% of them spare, and if I must only use 40% of the capacity of each breaker, it becomes quite difficult....hence my OP because those are both true in this case. We cannot assume that 'rip the board out and rewire' is the solution in all cases.



4. Critical pieces of kit can be supplied via a fused connection unit. No RA required.

Not if the manufacturer specifies a socket outlet.



5. Critical pieces of equipment can be supplied from a labelled designated socket ( no RA required for the application of this exception. For a bit of a belt and braces safety for the critical socket use one with a special shaped earth pin which are readily available so Mrs Miggins the cleaner cannot unplug the critical equipment and plug in her Henry.

The labelled circuit is normally going to be the one. I will recommend this to them a la section (b) above but there will still be one or two grey areas on this. Does 'general super complicated equipment only' work? I reckon it might as it happens. Anticipating wiping egg off face of course, but getting used to that. The odd shaped socket bit is quite interesting JP...I will go and look for that on the big yellow tablets of stone. But do you know of an odd shaped equivalent to a manufacturer specified 13A socket outlet? I will look into it. Not sure if I can specify changing the plug on a critical bit of kit though...we can't even cut the plugs off washing machines these days without nullifying the warranty, so I do see a possible glitch in that suggestion.



6. The RA exception does not apply to domestic premises.

This is kind of ,err, more special, than chez Miggins. However, you will be pleased to know that I did do cleaners' sockets and they are spaced for the flex on a Henry.... and they have RCD as a given. You can send Mrs P in with the one you bought her for Christmas




Can some one think of a circumstance where the application of good design, and applying 1-6 above, would require a socket not to be 30mA RCD protected and be supported by an RA?

As above JP. I'm going in with your 5. I really only want to know who has to write the Risk Assessment but it was fun replying to yours and I still love you.





Zs
 07 February 2015 08:08 PM
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John Peckham

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Zs

Have a look at the special edition of Wiring Matters 2015 on the subject of RCD sockets you can find on this site by typing the title in to the search box at the top of this page.

MK do 13A plugs and sockets with special shaped earth pins to prevent inter connection with ordinary 13A plugs and sockets.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 07 February 2015 08:22 PM
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spinlondon

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MK also do SRCDs which do not require special plugs be fitted, or adapters used for cleaning equipment.
 07 February 2015 08:33 PM
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John Peckham

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Spin

The sockets with the special 13A plugs and sockets are for the non RCD sockets for designated equipment. This is done to prevent other appliances from being plugged in.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 07 February 2015 08:45 PM
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spinlondon

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Originally posted by: John Peckham

Spin

The sockets with the special 13A plugs and sockets are for the non RCD sockets for designated equipment. This is done to prevent other appliances from being plugged in.

Yes, I am aware of that John.
However it may be simpler to use SRCDs instead, as no RA would be required, there would be no requirement to purchase and attach special plugs, no requirement to ensure all cleaners are competent (if that exception still applies) and there would be less chance of nuisance tripping, as each RCD would only be protecting a single socket-outlet.
 07 February 2015 08:52 PM
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daveparry1

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I like fitting rcd sockets, quick, easy and effective!
 07 February 2015 11:20 PM
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IronFreely

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To answer Johns question to me.... Clasic case of over compensation when faced with the knowledge of new requirements but with out an actual copy. Essentially I opted for both labels and risk assessment because both myself and the care taker agreed that by writting the assessment we could future proof the enforcement of our control measures beyond his employment and the labels were indeed one of the control measures set out in our risk assessment in order to discourage people from plugging anything other than the computers in each bay... Actually as it turned out this particular care taker was aware of Amendment 3 and actually asked if the work could be done to that standard so as not to have to worry about what someone may say in future periodic inspections, I felt his request was fair and certainly don't regret the decisions made, especially as it gave me a little kick up the bum to order my new book and get new EIC's in order, generally a useful learning expirince as well as a good bit of paid work.
In answer to another question... If I found myself in court being asked "what I was thinking by choosing to omit RCD protection?" I would answer, "following the guidance of BS7671 to the letter" and provide evidence in the form of the risk assessment and the note in BS7671 which says you can omit an RCD if labels or risk assessment is provided and point out i provided both.
I am given to understand that in the event of an incident it is more likely that a summons for ones paperwork be given rather than a summons to give evidence in person, either way I'd be using the paper trail to defend myself.
 07 February 2015 11:32 PM
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mapj1

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Well - I'm going to try and guess what was intended, rather than what was actually written because I don't think the intention has changed much with the 'new' rules. Emergency supplies to something that will be more of a health hazard if it loses a supply, and are unlikely to give someone a shock anyway, still need no RCD.

At home this situation is OK to be indicated by labels, and In the workplace this is proven by risk assessment, presumably by someone who understands the load, and why loss of supply to it would be a greater hazard than the shock risk if it developed a fault of the kind an RCD might detect.

Ergo, a socket saying 'Beware NON RCD socket ! - freezer only' may be OK in domestic, at work it should be written up.

However, there are not enough accidents to set the bar for RCD omission very high - actually we really need larger numbers of bodies. I'm not sure about IT kit, actually, I reckon its high shock risk as folk touch it and wheel their chairs over the flex and things - a ceiling mounted metal thingy however, or even a built in fridge is a lower risk of shock. )

The problem, is that most of the sockets in the land don't yet have RCD protection, and if we are honest, most haven't killed anyone, even the ones with LN reversals and no CPC, and so the desire to keep on using them is very strong - which led to the instructed persons thing being interpreted very liberally - did we mean it to apply to halls where play groups meet just because there is a caretaker in charge? I'm sure the reg-writers certainly did not.
I fully expect the RA thing to be equally liberally interpreted for the same reason. It will be cheaper for a large organization with lots of buildings to hire in some safety consultants, to do sums using the million pounds per life saved type of figure and show that in that setting, it is not necessary or desirable to add RCDs to the existing wiring (oh and by the way they are probably right).

Then there is the problem of RCDs in some places that trip far more than the normal risk assessment may assume, not because of a fault in equipment or circuits they protect, but because of conditions on the supply outside. I'm thinking of induced currents in overhead supplies and so on, perhaps the unlucky folk share the terra firma and a set of poles with an electric railway or a welding enthusiast for example.


I also think it might have been better to require either a larger or slower RCD rather than allow a total omission under RA, as it closes the "do nothing" loophole and once the covers are off, then suddenly a 30mA RCD is actually cheaper than a 100ma S type.

We might have been much better not changing the regs at all, but having an 'ask you boss for an RCD this Christmas " type of campaign to get an emotive response, not a technocratic one. But the IET can't do that, so the only lever it has available has been pulled instead, namely an amendment.

-------------------------
regards Mike


Edited: 08 February 2015 at 12:00 AM by mapj1
 09 February 2015 02:44 PM
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davezawadi

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We are having some problems here with what a risk assessment is, and its purpose.
Commonly having something written of a bit of paper (or electronic equivalent) is seen as adequate, but it is not. The RA itself is simply a risk management tool. In itself it is of no value or power to mitigate anything. The RA should list all the anticipated risks or risk scenarios and make some attempt to quantify them, perhaps as likely, possible, unlikely and impossible (there are often several of those). The next step is to decide what can be done to mitigate each risk, in a reasonable way (source : HSE). If the risk is very unlikely and mitigation very difficult a decision may be made to do nothing, which may be a reasonable conclusion.

Now to the OP. We have a risk assessment which says that loss of supply has very high risks (particularly in a medical life support environment). Also we have a very low risk of any other fault putting anyone (including the patient)at risk. The equipment is controlled closely, PAT every (name your period), class2, and all the rest. Would I fit an RCD? The answer is "not likely!". The reason is that RCD trips can be for many reasons and they are not known for absolute reliability, far from it. In this case I believe it provides no useful level of protection to anyone. The RA gives the things to consider, the opinion by me gives the reasons. I believe I can defend them to the ultimate level if required, I could not defend someone dying because of an unnecessary and useless RCD trip when no one was watching, just because BS7671 said it was a good idea, notice that IT IS NOT A REQUIREMENT (too risky to the committee that one). As for the manufacturers instruction to use a 13A socket (does it say a BS1363 one?), it means nothing useful and they could not defend such a requirement on any grounds except that the mains cable needs protection by the plugtop fuse! BTW Henrys are class 2 as well, but I suppose that you are providing protection from direct contact with the cable conductors when it is seriously damaged Zs. The question there is "is that the correct control measure, and is there a better way to mitigate the potential risk?". We can discuss that another time.

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 09 February 2015 04:08 PM
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John Peckham

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David Z

If it is medical life saving equipment you are talking about then it has to be 30mA RCD protected unless it is connected to an IT system where you have continuous insulation resistance monitoring anyway. No RA permitted to omit RCDs in Section 710.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
IET » Wiring and the regulations » 411.3.3

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