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Topic Title: Your advice please
Topic Summary: Old, TPN 400A, seemingly unfused.
Created On: 03 April 2013 07:37 PM
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 10 April 2013 03:11 PM
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Avatar for OMS.
OMS

Posts: 19895
Joined: 23 March 2004

I'm keenly watching the OMS/ dlane debate. Second hand has already been mentioned in there on the day the yellow phase failed.


Send your photo to someone like Bowers Electrical or Slaters Electrical to see if they have anything that matches both the switchfuse mechanical assemblies and the internal fuse carriages (GEC Simplex ?). There are others around but on your hourly rate don't spend too much time looking -

That will both inform the options arising from your switchgear characterization report and possibly allow early purchase if going down the make do and mend route.

Let me know if you want contacts for a replacement panel board for investment costing, outline planning etc

Regards

OMS

-------------------------
Failure is always an option

Edited: 10 April 2013 at 03:54 PM by OMS
 10 April 2013 05:32 PM
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dlane

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It does - isn't that why we have FATS, SATS, Soak Testing, black start testing and injection testing of principal pretective devices couped with detailed per commissioning inspction.

Yes we do, although in my experience they tend to be utilised to show that the initial installation is functional as per the specification. Having said that I don't tend to carryout injection testing of switch fuses unless I am feeling particularly awkward that day. :-)

I guess there is an argument that they go to someway to reducing the likelihood of reducing an inservice failure, but an installation is still suspect just after commission as it is started to be used in anger.


I think we could predict root cause of failure would be either the mechanical mechanisms now being operated much more frequently or electrical failure resulating from mal operation of those mechanical mechanisms. For a 50 year old board, a comprehensive lifetime of no maintenance would be a big justification for me - particularly when added to the potential impact on client operations of that failure.

I would agree to an extent, but it would also be highly dependent upon who is operating that switchgear. Mechanical switchgear operated on a regular basis in the appropriate manner is likely to benefit from that operation to prevent the mechanism from seizing, even in the case of aged switchgear.

Isn't that what's going on at the moment - the OP reognizes a number of problems and is canvassing opinions on it ?.

I am not sure, my perspective for this particular board was that it was a reaction a fault, which appears to have been a singular incident up till now. I didn't get the impression that a specific inspection of the breaker mechanisms had been carried out, but I could have misunderstood what was happening.

or the client carries on regardless in blissful ignorance

Not an unfamiliar situation of course. But unfortunately that is what most engineers are up against, it may be easy to suggest a replacement of the board based upon sound engineering practices but converting that into a solution accpetable to a client is always going to be a challenge.

Of course - but then you have a capital cost and a potential further installation cost - on the balance of probability you are throwing good money straight down the drain to stave off the inevitable for a short period of time.

Well yes you do, but then that may be more financially palatable in the short-term to accountants. But are you also going to install a new board without procurring some sort of spares for the installation? If not, give it a few more years and your new board may be facing a similar problem of obsolescence.

I wonder is this the only board in the building or are there others of the same type? In such situations I have recommended rolling replacements where a board can be replaced to release some spares for the remaining equipment which inturn is replaced as these spares are utilised.

So, I tend not to carry out straightforward EICR tick box inspections, althought the normal forms will be included. Give or take that this is a 400A supply though....not all our standard forms fit but I will make a decision on that later on. There will be an accompanying document in plain English which explains the findings.These accompanying documents, which are not required by BS7671 appear to be of more value to the client than the tick boxes. I use other standards in addition to BS7671. I guess you'd look upon it as added value. In this case, the clients clearly need to know what they have got in the switchrooms and what they can expect from them, and so on

One good aspect of writing your own report is that you can potentially sway the company into your line of thinking. If your preferred option is that of replacement sooner rather than later then a rolling program, if applicable, may be of interest to them and easier to substantiate. Another factor you could use is to inform them that the old board in its present condition has more value now to be sold as second hand rather than if they wait 2 to 3 years when it may just have a scrap value to it.

Kind regards

Donald Lane
 10 April 2013 06:48 PM
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OMS

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Originally posted by: dlane

It does - isn't that why we have FATS, SATS, Soak Testing, black start testing and injection testing of principal pretective devices couped with detailed per commissioning inspction.

Yes we do, although in my experience they tend to be utilised to show that the initial installation is functional as per the specification. Having said that I don't tend to carryout injection testing of switch fuses unless I am feeling particularly awkward that day. :-)

I guess there is an argument that they go to someway to reducing the likelihood of reducing an inservice failure, but an installation is still suspect just after commission as it is started to be used in anger.


I'd say it goes a long way to generally reducing early in service failure, you can't reduce risk to zero but an old, unmaintained board built to an obscure standard has to be risky wouldn't you say - if only on the basis of a statistical analysis of that bathtub curve we love.

I think we could predict root cause of failure would be either the mechanical mechanisms now being operated much more frequently or electrical failure resulating from mal operation of those mechanical mechanisms. For a 50 year old board, a comprehensive lifetime of no maintenance would be a big justification for me - particularly when added to the potential impact on client operations of that failure.

I would agree to an extent, but it would also be highly dependent upon who is operating that switchgear. Mechanical switchgear operated on a regular basis in the appropriate manner is likely to benefit from that operation to prevent the mechanism from seizing, even in the case of aged switchgear.

I agree - but this is switchgear that is having it's first inspection (and thus operation) in decades - a single operation of a switchfuse resulted in a very odd misalignment of the fuse carriage yellow phase not made - continuing operation is certainly going to present more problems.

If it had been properly maintained and "exercised" from new, i wouldn't have a problem with increased frequency of operation.

And then we have to consider risks to the person on site actually doing the switching - you'll have been close to enough panels that have closed into a fault or opened into earth to know the risks.


Isn't that what's going on at the moment - the OP reognizes a number of problems and is canvassing opinions on it ?.

I am not sure, my perspective for this particular board was that it was a reaction a fault, which appears to have been a singular incident up till now. I didn't get the impression that a specific inspection of the breaker mechanisms had been carried out, but I could have misunderstood what was happening.

I read it as a comprehensive EICR with some added value inspection and reporting going on - it isn't as a result of a fault investigation - it's the first findings of an internal examination of the switch gear.


or the client carries on regardless in blissful ignorance

Not an unfamiliar situation of course. But unfortunately that is what most engineers are up against, it may be easy to suggest a replacement of the board based upon sound engineering practices but converting that into a solution accpetable to a client is always going to be a challenge.

For sure - and no doubt people expect us to do for a shilling what any idiot can do for a pound - recommending a replacement based on sound engineering judgement and a reasonable fiscal approach is just an engineering professionals view - the client is free to ignore it and do what he likes. You'll have heard the saying about a good scare is as valuable to some men as good advice is to others. I'm not in the habit of holding a gun to the clients head - but they will get my unbiased professional opinon even if they don't like the conclusions.


Of course - but then you have a capital cost and a potential further installation cost - on the balance of probability you are throwing good money straight down the drain to stave off the inevitable for a short period of time.

Well yes you do, but then that may be more financially palatable in the short-term to accountants. But are you also going to install a new board without procurring some sort of spares for the installation? If not, give it a few more years and your new board may be facing a similar problem of obsolescence.

I wouldn't procure it without the spares list no, of course not - but keep in mind when you are considering buying a new board you have the whip hand and can usually acquire the spares at a good ore even zero price - if you are the one with the begging bowl out looking for that switchfuse that a particular seller has, and you have no alternative in the market place then you are going to pay a (often significant) premium - simple laws of supply and demand.

I wonder is this the only board in the building or are there others of the same type? In such situations I have recommended rolling replacements where a board can be replaced to release some spares for the remaining equipment which inturn is replaced as these spares are utilised.

It's the main switch board as far as I can tell Donald - the remaining kit is a variety of patterns of final circuit DB's


So, I tend not to carry out straightforward EICR tick box inspections, althought the normal forms will be included. Give or take that this is a 400A supply though....not all our standard forms fit but I will make a decision on that later on. There will be an accompanying document in plain English which explains the findings.These accompanying documents, which are not required by BS7671 appear to be of more value to the client than the tick boxes. I use other standards in addition to BS7671. I guess you'd look upon it as added value. In this case, the clients clearly need to know what they have got in the switchrooms and what they can expect from them, and so on

One good aspect of writing your own report is that you can potentially sway the company into your line of thinking. If your preferred option is that of replacement sooner rather than later then a rolling program, if applicable, may be of interest to them and easier to substantiate. Another factor you could use is to inform them that the old board in its present condition has more value now to be sold as second hand rather than if they wait 2 to 3 years when it may just have a scrap value to it.



Kind regards



Donald Lane


regards

OMS

-------------------------
Failure is always an option
 10 April 2013 07:05 PM
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Jaymack

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Originally posted by: Zs
I would recommend stepping beyond the normal EICR routine to all Inspectors.

An E.I.C.R., is a document to BS 7671 which in turn really applies to a limit of a 100A supply. Although, there's no reason why it can't be just used as a basis for a written report at higher amperages ............. that require much more experience and training.

Regards
 10 April 2013 07:27 PM
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OMS

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Originally posted by: Jaymack

Originally posted by: Zs

I would recommend stepping beyond the normal EICR routine to all Inspectors.


An E.I.C.R., is a document to BS 7671 which in turn really applies to a limit of a 100A supply. Although, there's no reason why it can't be just used as a basis for a written report at higher amperages ............. that require much more experience and training.

Regards


I wouldn't say an EICR is a method of inspection that's limited to sub 100A installations - it's equally relavant in a large district hopital as an example as it is in a small domestic house or small commercial premises.

If there is a need or contracted requirement to go further in terms of inspection, investigation and reporting on specific aspects of the electrical installation or indeed on other services such as emergency lighting, fire alarms or in this case the site panel board, then BS 7671 doesn't disallow this.

the condition report inspection schedule publishd in appendix 6 (informative) may or may not be applicable (in whole or in part) but the EICR remains a valid process (and a valid document) with an alternative schedule in place - such that it meets Chapter 62 (621.2 et seq, observing the note to that regulation) and Chapter 63 (specifically 634.1)

Experience ? - you got to do it, to get it, I guess

regards

OMS

-------------------------
Failure is always an option
 10 April 2013 07:54 PM
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Jaymack

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Originally posted by: OMS
I wouldn't say an EICR is a method of inspection that's limited to sub 100A installations - it's equally relavant in a large district hopital as an example as it is in a small domestic house or small commercial premises.

It can be used as a basis for higher amperages, as the man said.

If there is a need or contracted requirement to go further in terms of inspection, investigation and reporting on specific aspects of the electrical installation or indeed on other services such as emergency lighting, fire alarms or in this case the site panel board, then BS 7671 doesn't disallow this.

No question but that is implicit!

Experience ? - you got to do it, to get it, I guess

There's no substitute for hands on experience, which is usually a function of the capability of the "sponge", time, relevant exposure and making errors without major comeback! But it's a wise man who knows his limitations.

Regards
 10 April 2013 08:05 PM
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OMS

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There is no substitute for hands on experience as you say - I guess the secret is to get that experience under the supervision of a more experienced person who can recognise limitations - that way, the experience is both valid and lower risk.

How and where that overview is obtained is a perhaps more open to interpretation - this forum provides plenty of it I suspect - as one method at least

regards

OMS

-------------------------
Failure is always an option
 10 April 2013 08:32 PM
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Zs

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Originally posted by: Jaymack

There's no substitute for hands on experience, which is usually a function of the capability of the "sponge", time, relevant exposure and making errors without major comeback! But it's a wise man who knows his limitations.

Regards


Agreed, in spades. Which is where this forum plays such a vital role.

Whilst I have already made some recommendations for smaller issues in my drafting of the report I will not be making any recommendations in terms of the switchgear. As Jaymack suggests, that is indeed a limitation. I have never installed a control panel like these and need to have handled kit before I truly get it in my head. I work with engineers who have never handled kit and can already see that I am more limited than they because I need to have been inside it to know it. I would not even recommend a doorbell to a client because I've only ever installed one. Intercom....not on your nelly but I can tell you if the above are not fit for purpose.

With regard to the switchgear we are discussing. It may, as Donald suggests ,be appropriate to use existing gear as spares ( well I think it is Donald who said that but am now completely disconbobulated over who is saying what on this exchange and even see a bit of me in one of them ).

The building has two main intakes, both the same mixed brands, and a control panel in the stage area of the same mixed brands. Further there is the roof plant and the boiler area (OMG) which are equipped with panels of a similar age but quite different.

However, Alan touched on a critically dangerous situation way back on this thread and I am minded of the disintegration of parts and the unknown serviceabilty of old kit which has not been maintained over the years.

I know nothing of untouched metal degradation. Could write you a paper about work-hardenening and welding but nothing on neglected component metal parts. To test a weld you must test it to breaking point and render it useless. I assume the same for a metal switching mechanism?

I suspect that I will be suggesting a consultation from someone who specialises in this area.....Donald? fancy a trip to the theatre? Got a parking space and everything.... We'll see, I'll not be writing it for a little while yet but the draft is already on the go.

My role is to tell them about it all and to carry out the first proper inspection and test that the theatre has ever had. I have copies of the previous ones. Shocking.

Zs
 10 April 2013 10:31 PM
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UKPN

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"running repair? no maintenance?"

our poster should get out more, we have a vast project upgrading o/h to
ABC, metalclad cut-outs changed where reqd, the building industry is picking up and in my area, Cambridge, Harlow, Chelmsford, thousands of new connections are being provided.
not to mention the hundreds of technical queries handled every day, emergencies attended. we have a few million customers, its big business.

Regards.
 10 April 2013 11:19 PM
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Martynduerden

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Zs

At a proposed cost of 10k (oms) for the panel and c 8k install (oms) is it actually worth doing anything other than replacing it?

50 years old, no maintenance, failing operations ... Even if you start to maintain it spare if you can find them will be expensive and also ancient with no guarantees.

At OMS's 18k it's a bargain!

I wouldn't worry about specifying switchgear it's only 4 domestic boards per phase , in reality 400A is nothing to write home about MG for example do an off the shelf solution...

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 10 April 2013 11:44 PM
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John Peckham

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Zs

I would describe in plain English the deficiencies you have observed, the lack of maintenance records available at the time of your inspection and some of OMS nice words about economically and technically expired and perhaps point out the consequences of failure of the panel components on business continuity. Then some nice words about consideration being given to replacing the panel.

I would not go in to detail about replacement at this time but I would agree Martyn the answer is a nice new Schneider MCCB panel.

Or alternatively as the youngest member of my team said on one job whilst we were itemising all the defects on a very deficient installation, "Why are we going to all this trouble would'nt be easier just to put a Postit note on the invoice that says, It's f***ed and save all this writing".

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

http://www.astutetechnicalservices.co.uk/
 11 April 2013 08:52 AM
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dlane

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I know nothing of untouched metal degradation.

Generally the contacts won't degrade unless they are making poor contact to each other and arcing is occurring. The actual steel mechanism can corrode depending upon its plating protection and the atmosphere around them. Mechanism springs can weaken and corrode over long periods of time, again the leval of corrosion is down to the atmosphere.

If you have disimilar metals bolted together then corrosion can also cause corrosion.

The condition of arcing chute also need to be verified if they are fitted to this tyoe of switchgear.

I would also have concerns over the insulators and carriages. Over time and with heat resin / plastic materials can degrade, become brittle and break up or even worse break up during operation of the switchgear and cause a fault. It will depend upon the materials that have been used as to what to look for. Look for signs of cracking or de-lamination, discolouring of the material can be an indicator that it has been subjected to too much heat.

fancy a trip to the theatre?

Unfortunately (or fortunately, depending how you look at it) work commitments in Wales are keeping me busy at the moment and does cater for a certain amount of theatrical goings on in its own.....

Kind regards

Donald Lane
 11 April 2013 05:12 PM
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OMS

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I would not go in to detail about replacement at this time but I would agree Martyn the answer is a nice new Schneider MCCB panel.


Steady - I certainly wouldn't be recommending a swap from BS 88 protection in fused switches for MCCB's on existing cabling (particularly if there is aluminium cabling present) - not unless someone was willing to do a robust assessment on the submains anyway

My suggestion was based on a 50kA peak, 35kA 1 second Form 4 type 2 modular switchfuse panel board - not ganged MCCB's - the protection characteristics will be quite different.

Regards

OMS

-------------------------
Failure is always an option
 11 April 2013 05:21 PM
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OMS

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Originally posted by: UKPN

"running repair? no maintenance?"

our poster should get out more, we have a vast project upgrading o/h to

ABC,

LoL - a bit like stringing washing lines then - sling 'em up, judge the sag by eye - use noddy connections for service tails - not really rocket science is it.

metalclad cut-outs changed where reqd,

How far behind the programme are you in replacing them along with the fused neutrals now - about a decade or so ?

the building industry is picking up and in my area, Cambridge, Harlow, Chelmsford, thousands of new connections are being provided.

Thousands - I doubt it, and you're hardly in the epicentre of a construction boom now are you

not to mention the hundreds of technical queries handled every day, emergencies attended. we have a few million customers, its big business.

God love you and all - that's your business isn't it - as I said, if you'd invested in your infrastructure you wouldn't be dealing with those emegencies would you.

Never mind, I'm sure someone will say "well done" and pat you on the back.




Regards.


Regards

OMS

-------------------------
Failure is always an option
 11 April 2013 05:28 PM
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John Peckham

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I would think about a 12kA fault current for that installation. Yes I would want to know what the Zs values were on the distribution circuits before committing myself.

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

http://www.astutetechnicalservices.co.uk/
 11 April 2013 05:31 PM
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OMS

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To test a weld you must test it to breaking point and render it useless.


Would this be a bad time to mention non destructive testing - you can
x-ray it, gamma ray it, radiograph scan it or CT scan it, liquid penetrant test, magnetic particle inspection, acoustic scanning or eddy current test it - to name a few of the popular ones - coupled of course with monitoring of the welding technique itself (arc current, voltage, travel speed, thermal input etc) -

regards

OMS

-------------------------
Failure is always an option
 13 April 2013 12:56 AM
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Martynduerden

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Originally posted by: OMS

I would not go in to detail about replacement at this time but I would agree Martyn the answer is a nice new Schneider MCCB panel.




Steady - I certainly wouldn't be recommending a swap from BS 88 protection in fused switches for MCCB's on existing cabling (particularly if there is aluminium cabling present) - not unless someone was willing to do a robust assessment on the submains anyway



My suggestion was based on a 50kA peak, 35kA 1 second Form 4 type 2 modular switchfuse panel board - not ganged MCCB's - the protection characteristics will be quite different.

Regards

OMS


I hardly think there will beanyting in there out of the ordinary, mccbs come in a wide variety of kA ratings certainly suitable for that place I would imagine.

The MG panels do 36/50kA for 1 or 5s and are easily capable of form 4 types 2 & 6.

Given that there are solid links I suggest an mccb MAY be an improvement - certainly from an operational perspective.

A modular panel similar to what's there wood imo be a crazy route to take given the suggested installation and the availability of an off the shel solution.

Still this is all theoretical, unlikely to spend any thing like the 18k you suggested.

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com

Edited: 13 April 2013 at 01:05 AM by Martynduerden
 13 April 2013 11:08 AM
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Zs

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Testing a weld...Back when I took C&G fabrication and welding we simply smashed them up in a crushing machine. Oh well. Wrong again.

Now, a little bit of info for the onlookers. This thread amuses me by dint of a slight cloak and dagger going on. I couldn't take such accurate guesses about an installation could you? But worry not, Martyn, JP, etc....your amazing instictive knowledge of this kind of set-up, your stabs in the dark and assumptions really put the rest of us in the shade for not guessing what hasn't been said, with such skill. 12kA...great guess JP I chuckled.

But that'll be because you've been there?

I've an expert in large switchgear, from here, coming in for an hour on Monday too, by way of sharing opinions but mostly a delicate way of introducing someone who can do what they need. It's a two -way favour.

I'll be the one with the financial times under my arm and the slightly frazzled aura. Only two days left to get the testing finished and I have fogotten to book myself for the three days to write this. Send midnight oil.

One day I will bump this thread and let you know what was decided on.

I also anitcipate an opportunity for a full time electrician there. About two years' work I reckon. I'll bump if that happens, IMHO they need an older person with knowledge of the archaic and a whizz at trunking.

This thread has been informative. Thank you.

Zs
 13 April 2013 11:57 AM
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John Peckham

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Zs

Perhaps you could let us onlookers know what PFC you measured just to see how close my estimate was?

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

http://www.astutetechnicalservices.co.uk/
 13 April 2013 12:48 PM
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Jaymack

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Originally posted by: John Peckham
Perhaps you could let us onlookers know what PFC you measured just to see how close my estimate was?

Assuming that there is "PFC", do you mean physical dimensions?

If otherwise measured, they do bite back.

Regards
IET » Wiring and the regulations » Your advice please

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