Rewiring plan

[EFLImpudence]

Nothing wrong with ring finals. They have been around 70 odd years and proved themselves successful.

Quite right - but the reason and need for their introduction is no longer valid and therefore they are no longer necessary unless the route of the cable is actually an actual ring.

 

[EFLImpudence]

I've always liked RFCs

R stands for Radial as well.

 

[stillp]

the reason and need for their introduction is no longer valid

Redundant CPCs no longer a benefit?

 

[EFLImpudence]

Not really. That was not one of the reasons for their introduction.

Redundant live conductors are a definite disadvantage.

Do you 'ring' all the other circuits for that reason?

 

[stillp]

Not really. That was not one of the reasons for their introduction.

Who told you that? I used to be a member of a committee, one of whose members had been involved in the original concept studies of the ring final. He was adamant that the original brief was to design the safest and most reliable wiring system in the world, and the possible saving of copper came along later.

 

[securespark]

the original brief was to design the safest and most reliable wiring system in the world

Then I would argue the committee failed. The ring final circuit has potential danger built in, the radial final circuit is what I would term "failsafe".

 

[John D v2.0]

Why is it every time someone writes the word system, it turns into a broken link?

 

[deadshort]

Must be a fault with the system?

DS

++++++++++++++++++++
edit 19/7/17

Now fixed

mod
++++++++++++++++++++

 

[deadshort]

Must be a fault with the system?

DS
++++++++++++++++++++
edit 19/7/17

Now fixed

mod
++++++++++++++++++++

How camp is that !

DS

 

[securespark]

How about syste m?

Broken word, no broken link....

 

[stillp]

Then I would argue the committee failed. The ring final circuit has potential danger built in, the radial final circuit is what I would term "failsafe".

At the time, I would think that the risks that could arise from an open-circuit cpc were greater than those from the possibility of exceeding the CCC of the conductors.

Remember that in those days a load greater than 1.5kW was unusual. I have an electric kettle from the 50s that is 1kW, and an iron that is only 500W.

 

[JohnW2]

Redundant CPCs no longer a benefit?

Quite so. As I'm always saying, when it comes to pros and cons of ring finals, CPC redundancy is the one beneficial thing I can think of.

Of course, as someone else is likely to point out if I don't, one can build in CPC redundancy (aka 'high integrity earthing') without having to have a ring final. That would, I suppose, the the best of both worlds.

Kind Regards, John

 

[EFLImpudence]

Who told you that? I used to be a member of a committee, one of whose members had been involved in the original concept studies of the ring final. He was adamant that the original brief was to design the safest and most reliable wiring system in the world,

As said, failed then, as per the redundant live scenario.

and the possible saving of copper came along later.

The saving of copper was a result of what they were working with.

A BS3036 15A radial had to have conductors with a CCC of ≥20.69A so 7/.029 (method C 23A) I presume.
In order to double the amperage they merely needed to complete the circuit(ring) back to the CU.
A BS3036 30A radial would have required conductors with a CCC of ≥41.37A and would have meant running a new cable of 7/.052 (method C 46A)(9.5mm² equivalent).

The CCCs do seem a bit low compared with what we are used to today but that is what is in the tables I have found.

 

[EFLImpudence]

Don't forget, you are perfectly entitled to wire whatever circuit you like in a ring.

However, the subject is the specially dispensated Ring Final Circuit with all its conditions and particular requirements which, nowadays with the narrow gap between a 27A CCC cable and a 32A MCB hardly seems worthwhile.
If only there were a, what, 3mm² cable with a CCC of 32A, the whole thing would go away.

 

[securespark]

4 milli?