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Discuss Final Circuits - Ring or Radial? in the Electrical Forum area at ElectriciansForums.net

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OldskoolUpNorth

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I was speaking to an Electrical Engineering suit not too long ago,

He reckons that there's talk of Ring Final Circuits being done away with and the preference to install Radials only.

Anyone else heard this little gem.

Whats the general preference of everyone for the two systems????

Anyone already doing just Radials??


Ta,
 
The getting rid of rings is a hoary chestnut that as been going around since I started my apprenticeship too many years ago now to bother with. As far as I'm aware there is no indication that they will be going in the near future.

Like all circuits for me the design of them would take many factors into consideration and whatever is the most appropriate for installation is the one I would use. I have to admit working overseas for many a year as well as back home I do prefer radials as a rule of thumb for kitchen appliances. I like the Fridge/freezer, W/M D/W on a separate radial, but the power sockets I would most likely leave as a ring, unless there is a good design reason not to.

I like ring mains in commercial/industrial as well. It seems now that a norm is if you have 7/9 16amp sockets then the modern sparks would install them on 7/9 radials, where I would use a ring main and tap off. Again though you would design the circuit as what is best for the situation
 
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OldskoolUpNorth

  • Thread Starter Thread Starter
  • #4
The getting rid of rings is a hoary chestnut that as been going around since I started my apprenticeship too many years ago now to bother with.
Got the impression there's a new discussion been started by those up on high about it.

We were on about industrial but he seemed to reckon it would apply to all sectors.

Sure your right tho malcolm if it's been banded around for that long.
 

Midwest

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Arms
Esteemed
I'm using the 'LearningLounge' for retraining. On the subject Ring/Radial, ring circuits are primarily used in the UK. Inroduced after WWII, when there was an acute shortage of copper. There are disadvanatges, it encourages the use of too many spured circuits, missing or loose connections (i.e. one leg of the ring) resulting in cable overloads & too many cable connections in terminals with potential for overheating.

Apparently the it may be discouraged in future wiring regs, coming from the EU.
 

Des 56

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Arms
Esteemed
In these days of cost and energy preservation,the ring possibly has a better case for keeping than ever before and in all sectors

I have heard nothing lately
It is an old old bone of contention, the anti ring section has always been around,apparently they argue it out at the IET regularly, more as a tradition I suspect
 

Jimmy Boy

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Arms
As i have said in the past, setting aside the load issues, the biggest problem I see with radials is loss of the cpc connection after the first and before the last point of use, this could be easily cured by making the radial a 'Dual Earth ' circuit which would require a 4 core cable or a separate cpc run with the 3 core..I can't see it happening
J
 
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OldskoolUpNorth

  • Thread Starter Thread Starter
  • #10
As i have said in the past, setting aside the load issues, the biggest problem I see with radials is loss of the cpc connection after the first and before the last point of use, this could be easily cured by making the radial a 'Dual Earth ' circuit which would require a 4 core cable or a separate cpc run with the 3 core..I can't see it happening
J
There's already a reg in BGB (can't remember the number off top of my head) but radials running over 10mA need seperate earth of 4mm or more - poss industrial but seeing as I don't do industrial I don't know.
 
Midwest again this Ring circuits only being used in the UK is another Hoary old chestnut. Yes in a domestic situation I can't think of another country that uses them, perhaps a few old colonial places, but in the main domestic circuits are radials .............

But here I design many a ring circuit in offices, especially for IT installations, where we use 4mm ring finals. As I highlighted in my OP in commercial/industrial a ring main around a building for BS 60309-2 sockets, appliances etc is a much more efficient cost effective solution that individual radial circuits from a DB


 

Jimmy Boy

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Arms
There's already a reg in BGB (can't remember the number off top of my head) but radials running over 10mA need seperate earth of 4mm or more - poss industrial but seeing as I don't do industrial I don't know.
It's under the high integrity earthing section mainly used for IT where cumulative earth leakage is an issue
J
 

Midwest

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Arms
Esteemed
'Midwest again this Ring circuits only being used in the UK is another Hoary old chestnut' (sorry forgot to hit the reply with quote)

Only quoting what I have researched, but if you can show me differently? Wikipedia it, there are citations.
 
Totally agree, the benefits of a rfc are many. Could never understand why they have never taken off in other countries?
 
G

Guest55

  • Thread Starter Thread Starter
  • #16
If rings are being phased out it will have to wait until the 18th regs then :)
They are of use in kitchens but i still prefer radials.

* Gets popcorn , could be a loooong thread lol.
 
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SW1970

  • Thread Starter Thread Starter
  • #17
It's under the high integrity earthing section mainly used for IT where cumulative earth leakage is an issue
J
But can also be a problem in domestic with the amount of gadgets we plug in these days. A few PCs here and there, games units, LCD TVs, modern hifi, under desk home UPS units etc and it all adds up. Have seen 17mA on a domestic radial before. Does anyone actually check protective conductor currents on a routine basis other than when on a tripping RCD call out?
 

Jimmy Boy

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Arms
But can also be a problem in domestic with the amount of gadgets we plug in these days. A few PCs here and there, games units, LCD TVs, modern hifi, under desk home UPS units etc and it all adds up. Have seen 17mA on a domestic radial before. Does anyone actually check protective conductor currents on a routine basis other than when on a tripping RCD call out?
Don't suppose they do, a good point tho, although I would say if you had 17mA on one Radial I would want to know what the hell was that leaky. I did look in to buying a clamp meter for this purpose as I am unsure if my normal clamp will measure low values like that.
J
 
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SW1970

  • Thread Starter Thread Starter
  • #19
Not all clamp meters do; need one that can measure mA. Although can put a multimeter in series if able to safely disconnect earth for the test and able to turn all the gadgets on.
 

Jimmy Boy

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Arms
Not all clamp meters do; need one that can measure mA. Although can put a multimeter in series if able to safely disconnect earth for the test and able to turn all the gadgets on.
Is that safe ha ha ha ! I'm off to look at my clamp
J
 

Jimmy Boy

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Arms
Well I have the fluke 321, specs say for Amps 0-400.00 it has a 3 digit display, just out of interest I put it around a tail and pulling 11A put it on the main E get a reading of 00.6 switch the kettle on goes up to 02.1 is this right ? or is the meter out of range ? how can it register 400A if I only have two digits a decimal point then one digit ?
TNCS PME supply
J
 
S

SW1970

  • Thread Starter Thread Starter
  • #22
It can't measure mA. This is the spec from the fluke website:

Range: 0-400A Resolution 0.1A
Range 0-40A (Fluke 322 only) Resolution 0.01A

A spec for a mA meter will be something like a 3mA range with resolution of 0.01mA and 30mA with resolution of 0.01mA, etc.

Not sure what's going on with your readings there.
 
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PC Electrics

  • Thread Starter Thread Starter
  • #23
I generally prefer radials, but the rfc has its uses. For example, i am currently wiring a small work area for a company. The heavy duty kit has its own 3ph supply or runs on air. But they need sockets to plug in some lights and over a small bench area. I would normally have put the sockets on a radial, especially as the area is only the size of a single garage, however I cannot avoid running some cable in insulation, method 103. This reduces 2.5 to 17A. So I cannot put in a 20A radial, so instead I'm putting in a 20A rfc (I would have made it 25A but couldn't get a 25A RCBO without special ordering it).

In domestic and commercial the rfc also has the advantage of "reach". With it's substantially reduced volt drop compared to a radial and it's ability to share the load over two legs, an rfc can be installed in a largish area that might require several radials (IT considerations aside). Or it can be used to reach third floor bedrooms involving long initial runs.

Rfcs are also useful for high integrity earthing, as you don't need to install an extra g/y return cpc as you do with radials.

Don't forget that an rfc does not have to be 32A/2.5mm. Other ocpd/cable combinations are available!

Viva la rfc! (even though I prefer radials)
 

Jimmy Boy

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Arms
It can't measure mA. This is the spec from the fluke website:

Range: 0-400A Resolution 0.1A
Range 0-40A (Fluke 322 only) Resolution 0.01A

A spec for a mA meter will be something like a 3mA range with resolution of 0.01mA and 30mA with resolution of 0.01mA, etc.

Not sure what's going on with your readings there.
Thanks buddy I couldn't quite work out the zero-400 zero is just that isn't it ?

Steve
 

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