A1 ring final circuit

[knasher]

Hi,
Just browsing through OSG (living the dream!).
Why is an A1 ring final circuit only protected by a 30/32A breaker when the max current carrying capacity of a 2.5 cable is 27A? (page 134 of OSG, column 6). Apologies in advance if I'm missing something very obvious. Thank you

 

[isitnow]

because its a ring the csa is basically doubled to 5mm because the two 2.5mm conductors

 

[knasher]

Thank you isitnow!

 

[Guest123]

because its a ring the csa is basically doubled to 5mm because the two 2.5mm conductors

Gustav would be turning in his grave if he read that!:disguise:

 

[oldtimer]

Me thinks the reason why it is protected by a 30/32 fuse or cb is a thing called ohms law ie on a ring half the current flows down one leg and the other half down the other leg so max current on each leg is 16 amps but dont worry I think in 10 years the ring will be phased out because that and the 13 amp socket is all there is left to harmonise

 

[isitnow]

Gustav would be turning in his grave if he read that!:disguise:

its correct in the simplest form without explaining that the ring acts like two radials but the load (because of the ring) in each direction is half the total and because of this a cable with a smaller csa can be used, but as we know this depends on equal loading on the ring which is near impossible so sometimes it may be practical to use a cable with a larger csa. Happy now lenny or are you going to read threads and post useless comments without actually contributing any information?? and perhaps youd like to know that the ring circuit came into effect to save the use of copper after world war 2 when rebuilding the cities enough info now?
.

 

[Engineer54]

its correct in the simplest form without explaining that the ring acts like two radials but the load (because of the ring) in each direction is half the total and because of this a cable with a smaller csa can be used, but as we know this depends on equal loading on the ring which is near impossible so sometimes it may be practical to use a cable with a larger csa. Happy now lenny or are you going to read threads and post useless comments without actually contributing any information?? and perhaps youd like to know that the ring circuit came into effect to save the use of copper after world war 2 when rebuilding the cities enough info now?
.

Not at all, not if the FRC is wired in a staggered ring configuration, the load will be relatively balanced!!

Oh, and the copper saving was only a part of the reasoning behind the FRC, this is a common miss-conception and mainly banded about by those that want to see the demise of the FRC, usually by inexperienced electricians that can't fault find on them!!

 

[MarkieSparkie]

Gustav would be turning in his grave if he read that!:disguise:

Sorry mate you lost me with that reference, like to explain?

 

[Guest123]

Sorry mate you lost me with that reference, like to explain?

I was referring to our forefather Gustav Kirchhoff and hi circuit laws.

 

[Guest123]

its correct in the simplest form without explaining that the ring acts like two radials but the load (because of the ring) in each direction is half the total and because of this a cable with a smaller csa can be used, but as we know this depends on equal loading on the ring which is near impossible so sometimes it may be practical to use a cable with a larger csa. Happy now lenny or are you going to read threads and post useless comments without actually contributing any information?? and perhaps youd like to know that the ring circuit came into effect to save the use of copper after world war 2 when rebuilding the cities enough info now?
.

If you have a read of my 9,400 other posts you will see how much useful info I share with the entire forum.

It's only when I see the unguided posting inaccuracies that may confuse other members that I raise questions on it, simply to make sure that correct info is then given.

One other thing, please don't proceed to lecture me in the history of the R.F.C, google isn't always accurate.:icon6: