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Topic Title: RING FINAL CIRCUIT
Topic Summary: Should they be banned for new work
Created On: 09 November 2011 07:33 PM
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 09 November 2011 07:33 PM
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John Peckham

Posts: 7401
Joined: 23 April 2005

I was having a chat with some old sweats from the industry and one set the hairs running with, " Ban all ring circuits". All the others bar one agreed. I did not express an opinion but listened to their reasoning.

To me as a person who has to test RFCs they are a pain in the backside.

Thinking about it if there is an open circuit in live conductors it fails in an unsafe condition potentialy. Onc a radial circuit if a live conductor goes open ciruit it fails in a safe condition.

For domestic kitchen circuits they may be useful for distributing loads around the ring but that is about it.

Should we harmonise with the rest of the world and install radial circuits only?

Light blue touch paper and retire.

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

http://www.astutetechnicalservices.co.uk/
 09 November 2011 07:41 PM
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primo

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Surely that's close to banning tea?! Only a pain when there's a fault though eh? Which is almost always in the most awkward place to locate and remedy....the kitchen!
 09 November 2011 07:41 PM
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OMS

Posts: 19541
Joined: 23 March 2004

In my opinion john - RFC's are a perfectly good circuit design for flexibility, convenience, safety and security of supply.

You comments on failing to an unsafe condition are not really valid - it would be very rare to find enough load on an RFC to thermally stress conductors - we don't have any problem making a demand on the CPC in a broken state for protection from high protective conductor currents do we.

I get the impression that the inspectors of the last decade have over dramatized the issue of open circuit rings - how many are actually found (and we could include figure 8's in that) and of those how many are actually in a dangerous condition (and not just dangerous in the mind of the tester).

If we want to go continental then fine - but lets bin the 13A socket outlet whilst we are about it.

If not then we should keep the RFC and educate installers better

Regards

OMS

-------------------------
Failure is always an option
 09 November 2011 07:48 PM
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daveparry1

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I've always spoken in favour of rings John, but my main concern is that they are so easily (and regularly) abused by people adding more and more spurs to them. Also there are many quite experienced sparks that i've come across who don't really know or understand how to test them properly. On almost every c/unit change I find at least one ring conductor o/c!
I have installed radials in bedrooms on the last few re-wires i've done and am slowly coming around to the idea that might be a better way to go,

Dave.
 09 November 2011 07:48 PM
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John Peckham

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OMS

You wre leaning on the other end of the bar when the bloke at the other end suggested producing hats with "Ban Ring Citcuits" on them.

I find loads of open ring circuits so that's not a good argument. As for not being much of a problem the usual 2.5/1.5 T&E has a conservative rating of 27A clips direct with no doubt buckets of headroom for short term loading.

No keep the 13A socket no 2 pin or 2 pin with a scaping earth unfused plug for me.

As for improving the standards for installer that is not going to hapen with the continued dumbing down of education and training.

Nice radial circuits much better than RFCs.

OMS was the only lone voice at that gathering readers!

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

http://www.astutetechnicalservices.co.uk/
 09 November 2011 07:49 PM
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GeoffBlackwell

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John - are you in the pay of Group Schneider - ban them if you like, but remember that BS 1363 socket outlets will follow them out the door and you will be left with similar restrictions on the numbers of socket outlets on a radial that other countries have.

I suppose next you will be advocating joining the Euro .

Are you still going to ELEX on Friday - if so I will see you there .

Regards

Geoff Blackwell
 09 November 2011 08:04 PM
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OMS

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OMS was the only lone voice at that gathering readers!


I was John - because the rest of you didn't have a convincing enough reason to ban the RFC.

Being in a minority doesn't make you wrong - just different

Alas, I will not be joining you at ELEX either - it's not all beer and skittles at the coal face you know

Have a good one

OMS

-------------------------
Failure is always an option
 09 November 2011 08:05 PM
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John Peckham

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GB

Yes I will be there on Friday. The tea and bacon rolls are on me.

No I am not in the pay of some continental company and no I would not advocate joining the Euro.

Nothing wrong with radial circuits there is even a nice picture of one at the back of BS7671.

So what's wrong with radials an d 13A fused plugs?

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

http://www.astutetechnicalservices.co.uk/
 09 November 2011 08:10 PM
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daveparry1

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So what's wrong with radials an d 13A fused plugs?
-----------------
Nothing at all John!
 09 November 2011 08:18 PM
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GeoffBlackwell

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Without the RFC the push to replace the BS 1363 plug with a smaller easier to mold one will not be resisted.

I not sure of the exact requirements but I believe that French installations use 5 socket outlets on a 20A radial (possibly 8 in some circumstances).

Now given our house construction methods - how much of the joists around the CDU will be left with all the radial circuits we will need to maintain a reasonable number of socket outlets per installation.

BTW thats is Customer Distribution Unit [CDU] not Consumer Control Unit [CCU] because the French think we are going to eat them if we use that terminology .

Regards

Geoff Blackwell
 09 November 2011 08:20 PM
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mikejumper

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Originally posted by: daveparry1
On almost every c/unit change I find at least one ring conductor o/c!
Dave.

Likewise, it's got to the stage where I expect it.

An interesting variation on ring circuit design I come across occasionally is each leg in a separate mcb or fuse.

You'd wonder what the installer had in mind (if anything).
 09 November 2011 08:30 PM
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alancapon

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I had a different variation in a house I used to own. Three 20A BS3036 radials serving upstairs, downstairs (except the kitchen) and the kitchen. Unfortunately, someone had joined the three ends together. It took a while to sort out what had happened!

Regards,

Alan.
 09 November 2011 08:33 PM
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daveparry1

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I had one like that the other day Mike, it was only a couple of socket replacements in a kitchen. The customer said to me, "i'll go and turn the power off for you cos you have to turn off two breakers" ! I found one of the ring conductors has been swapped with a radial, whether this was by someone working on it or it had always been like it who knows?

Dave.
 09 November 2011 08:46 PM
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perspicacious

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"I found one of the ring conductors has been swapped with a radial, whether this was by someone working on it or it had always been like it who knows?"

Very common to find that the IH radial had been connected to one leg of the RFC with the other leg of the RFC in its own OPD.

Mind you, that was in the pre Part P days where proper time served electricians (aka wiremen) carried out the work but didn't have enough strength left at the end of the install to crank the I and C tester round...........

Regards

BAD
 09 November 2011 08:52 PM
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Legh

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Its quote common to find broken rings, I've had a couple in the last couple of months, usually covered by a 32A MCB, loading on them has been nothing to write home about and so just coded them as code II.

As far as installation of power circuits go I prefer radial circuits where you can still put as many skt outlets on the circuit as you like, its easier to run, test and fault find.

RFCs come into their own when used in open plan office and commercial environments where coverage is large but not necessarily of a high load, and as already suggested, RFCs are fine for kitchens where loading is likely to be higher and accessories are small. and actually quite good when using larger sized conductors to supply 16A commando sockets.
I've had occasion to use them on lighting circuits where large number of lights need to be supplied in a kitchen by one circuit and to reduce the R2 value

So the answer is flexibility. As least in this country we have a choice even though its through inheritance.

Legh

-------------------------
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."
 09 November 2011 09:08 PM
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ebee

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John,
you are a very naughty boy,
suggesting rings might be a bad thing.
They have a lot to commend them, though they have their problems too.
But then so too the radials.
Now go to the naughty corner for suggesting our beloved rings are questionable.
Ring Finals are British, it is Patriotic to install rings.
"Great British Craftsmanship"



PS ref the two legs of a ring in separate ways on a CU. I found two radial lighting circuits joined together at the Ph & N (same result really a lighting ring with two separate breakers)

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 09 November 2011 09:09 PM
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ebee

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In fact, let`s make rings compulsory!

Set us above Europe

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 09 November 2011 09:47 PM
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psychicwarrior

Posts: 220
Joined: 18 October 2010

i'm probably the least experienced of all on this thread......

what's this problem with testing rings... how hard can it be!
i think they are useful. so are radials........i like having options.

how unsafe are they really.... any stats on fires, overloads etc?

i laugh at the 'ban it' thing....it reminds of the moronic standards of driving on our roads....we are all dragged constantly down to having conditions to cater for the lowest skill standards (marketed as health and safety improvements), rather than having measures to ensure higher standards, or get rid of the ones who cant achieve them.

Part P - competent person registration schemes - yeah right!


easy now ;-)

BTW, is there some sort of masonic electricians club that defines what we can and cant have and who can belong to it ;-)
 09 November 2011 10:08 PM
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mikejumper

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Originally posted by: psychicwarrior
BTW, is there some sort of masonic electricians club that defines what we can and cant have and who can belong to it ;-)

Yes. It's called the NICEIC.
 09 November 2011 10:09 PM
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daveparry1

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how hard can it be!
-------------
Not really hard as such but it can be very time consuming when doing a c/unit change for instance and you're trying to find an o/c ring conductor or the cause of a poor i/r reading. Sockets, fcu's, junction boxes etc. hidden behind kitchen units, wardrobes, cupboards etc, not to mention piles of boxes, clothes, rubbish etc hiding them from view! I know we could have similar issues with radials but at least if there's an o/c connection somewhere something would have stoped working and gives us a clue where to look!
And no, i'm definitely not anti-rings but there are times!!

Dave.
IET » Wiring and the regulations » RING FINAL CIRCUIT

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