ring final vs ring

[bluetobits]

I think Phil described it well enough in post #7

 

[Deano93]

the new material they give out can alot of the time contradict what older material says . when you have to learnt the old and new it just doesnt make sence to have changed it in first place . oh well lol

 

[Murdoch]

And never go back to different breakers 

Unless they are wired by builders or DIYers .....

 

[binky]

ok so the difference between a ring main and a ring final ? im so confused right now

Nothing, its a ring circuit or a radial circuit.

Bit of history for you, rings came out of a very high copper cable price, effectively by using 2.5mm FTE as a ring it gives the equivalent of 5mm cable, so can take 32A easily. Now you could achieve a 32A circuit by using 4mm FTE as a radial, but in reality it's a PITA coz modern sockets don't have big enough terminals, and if you want to take a spur  off the cct, 3off 4mm cables definetly do not fit in the sockets terminals. Now a radial circuit in 2.5mm can take 26 A from memory but few manufacturers supply 25A MCBs, so generally it would be on a 20A MCB. Why would you use a 20A radial cct? 2 reasons, lack of loading on cct, 20 A is roughly 5kW so will handle the demand of bedrooms / lounge etc without much problem. Kitchens, which tend to have lots of appliances like washing Machines / tumble driers will work quite happuly on 20A until you add something like a 3kW kettle, which is enough to overload the MCB and trip the cct. So high demand areas like that tend to be better off on 32 A cct, which means a 2.5mm ring ( or 4mm FTE radial, but that is a PITA and generally costs more for the cable).

 

[Lurch]

Bit of history for you, rings came out of a very high copper cable price

Not directly, AFAIAA the reason for the ring main was it was easy to convert a couple of 15A circuits into a ring and add a few more sockets along the way without worrying about stretching the limits of the radial circuits.

 

[pewter]

Radials and 4mm are very common on my jobs,

I hardly ever fit a ring.

2x radials is better then 1x ring (as long as there is enough MCBs)

 

[steptoe]

I wrote a good reply to this explaining it , but it disappeared, some other strange things have been happening lately too in the forum.

nevermind.

btw @binky you are half right, 70% wrong

 

[binky]

think your abacus is busted too!

Not directly, AFAIAA the reason for the ring main was it was easy to convert a couple of 15A circuits into a ring and add a few more sockets along the way without worrying about stretching the limits of the radial circuits.

Not heard that one before Lurch. I do remember and have encountered Aluminium cables which I understand was cost saving.

 

[SPECIAL LOCATION]

im currently doing a electrician course and im at a stage where i am going through ring and ring final circuits, i get how both of these work but i cant seen to understand why choose one over the other ? what are the situations you would use each one ? thanks in advance

thanks guys ,

my understanding is that a ring starts at CU and ends CU . radial ends at last outlet , and a ring final is from what i know its something to do with how its connected at the CU but i cant find out why. its something like it instead of going back to the same breaker they go to seperate ones so if the circuit was to break you effectively have two radial circuits - so am i confused ?

It sounds to me like your "instructors" are not very good.......   is this a 'short course' by any chance?.

I think you need to be clear about the standard definitions used within BS7671.....

Part 2 has quite a helpful alphabetical list.  Key points you need to get your head around are:-

A circuit; comes from a single source of supply. (protective device, Fuse/MCB/RCBO).

A final circuit; comes from a single protective device in a distribution board, (or consumer unit), and supplies current using equipment, (eg sockets, lights, appliances, machinery etc.)

A distribution circuit; supplies other switchgear or distribution boards, (also know as Sub-main). 

A ring circuit comes back to the same single source of supply. (protective device, Fuse/MCB/RCBO).

A radial circuit; does not come back to the supply source. (protective device, Fuse/MCB/RCBO).

etc...

Now providing all of you cable calculations and loadings and protective devices are correct...

There is no reason why final or distribution circuits cannot be configured as either ring or radial arrangement.

So if its a final circuit configured as a ring....  It would be called a 'ring final' ( and the term 'ring final' has been in Part 2 definitions for a few years now). 

Of course we then get into "Spurs"  ....  (which are basically 'radial' branches off 'ring' circuits!!!)

opcorn  

 

[Lurch]

I do remember and have encountered Aluminium cables which I understand was cost saving.

Yep, before my time but that was 70's, 60's? Rings have been about longer than that.

 

[Doc Hudson]

Yep, before my time but that was 70's, 60's? Rings have been about longer than that.

1940's according to Wiki.  https://en.wikipedia.org/wiki/Ring_circuit  

The ring circuit and the associated BS 1363 plug and socket system were developed in Britain during 1942–1947.[1] They are commonly used in the United Kingdom and to a lesser extent in the Republic of Ireland. They are also found in the United Arab Emirates, Singapore, Hong Kong, Beijing, Indonesia and many places where the UK had a strong influence, including for example Cyprus and Uganda.

Doc H.

 

[Lurch]

1940's according to Wiki.

Makes sense, ISTR the 'extend 2 radials' thing being a a post war materials saving technique.

 

[Evans Electric]

Deano  ... consider the old method in domestic premises , back in the 1940s  - 1950s  , rubber cable ,  sockets could have been a mixture of  2A x 2 pin .... 5A x 2 pin ...5A x 3 pin .... 15A  x 3 pin   or use a bayonet  adaptor, remove the light bulb and plug into the ceiling rose.  

The 15A sockets would all be wired back separately .

So back then ,  one simple ring main using 13A  BS 1363 sockets would be adequate for a small house .  

It saved cable .

It could be added to.

It standardised all the plug tops . 

Not uncommon to find a 4 way board for a house :-

 8 Lights

 6  Plugs

Cooker

Imm. Htr.

You need to know that the names of things in this trade are like the staircases at Hogwarts , they keep being  changed by  those above us  and the use of initials is encouraged until idiots like me don't know what others are talking about . 

To understand types of Supply you need to speak latin and it all makes sense ..so for  Earth say Terra , as in Terra Firma  then a TN-C-S  begins to make sense.

Spur units are now FCKU  or something .

Fuseboards or "The Board"  are CUs  or a Consumer's unit shortened to Consumer Unit.

The obvious one of course was to change all the cable colours .

Fuses are now OPD s  or something similar , so it goes on .

Conduit & trunking is now Cable Management .    And so it goes on.

 

[kerching]

...and an Electrician is now an NICEIC Fund Raising Partner with special responsibility for ECs Barbadian jollies and LFBs pies

 

[Deano93]

Deano  ... consider the old method in domestic premises , back in the 1940s  - 1950s  , rubber cable ,  sockets could have been a mixture of  2A x 2 pin .... 5A x 2 pin ...5A x 3 pin .... 15A  x 3 pin   or use a bayonet  adaptor, remove the light bulb and plug into the ceiling rose.  

The 15A sockets would all be wired back separately .

So back then ,  one simple ring main using 13A  BS 1363 sockets would be adequate for a small house .  

It saved cable .

It could be added to.

It standardised all the plug tops . 

Not uncommon to find a 4 way board for a house :-

 8 Lights

 6  Plugs

Cooker

Imm. Htr.

You need to know that the names of things in this trade are like the staircases at Hogwarts , they keep being  changed by  those above us  and the use of initials is encouraged until idiots like me don't know what others are talking about . 

To understand types of Supply you need to speak latin and it all makes sense ..so for  Earth say Terra , as in Terra Firma  then a TN-C-S  begins to make sense.

Spur units are now FCKU  or something .

Fuseboards or "The Board"  are CUs  or a Consumer's unit shortened to Consumer Unit.

The obvious one of course was to change all the cable colours .

Fuses are now OPD s  or something similar , so it goes on .

Conduit & trunking is now Cable Management .    And so it goes on.

Thankyou

 

[Andy™]

the powers that be like to keep changing the name of things...

it used to be 'live'. then 'phase'. now its 'line', but just to complicate things even more both line & neutral are also 'live'

we also had direct & indirect contact. that was too complicated so its now basic & fault...

 

[Evans Electric]

the powers that be like to keep changing the name of things...

it used to be 'live'. then 'phase'. now its 'line', but just to complicate things even more both line & neutral are also 'live'

we also had direct & indirect contact. that was too complicated so its now basic & fault...

Now theres a new one on me !!

Can I still call shocks .."Belts" or "Pissers"  or have they changed too  ?  :innocent

 

[kerching]

Can I still call shocks .."Belts" or "Pissers"  or have they changed too  ?  :innocent

Up here it is BELT for a medium sized shock, TICKLE for a smaller shock, CLOUT or A REET CLOUT for a larger size shock.

if it is LIVE i.e. on Supply then it is said to be WICK

all these will be in the 18th edition Amd 99 due out September 2018

 

[Andy™]

im surprised the colours are not due to change again. they havent been altered for too long now

 

[Blue Duck]

Pink n brown I hear...

CCU cooker control unit or consumer control unit??? 

Fuse box & cooker switch make more sense to me.