Final Circuit conductor sizes in OSG 8.2

[ringer]

Referring to pages 158-159 in the OSG

Table 8A
Type, OPD(A)
A1 Ring, 30 or 32 .......etc

8.2.3 Conductor size
....The as-installed current-carrying capacity Iz so calculated must not be less than:
20 A for ring circuit A1

Am I reading/interpreting this correctly when I say that the OSG is telling us you can have a RFC made up of cable with a capacity of 20A and an OCPD of 32A?

 

[ian.settle1]

Referring to pages 158-159 in the OSG

Table 8A
Type, OPD(A)
A1 Ring, 30 or 32 .......etc

8.2.3 Conductor size
....The as-installed current-carrying capacity Iz so calculated must not be less than:
20 A for ring circuit A1

Am I reading/interpreting this correctly when I say that the OSG is telling us you can have a RFC made up of cable with a capacity of 20A and an OCPD of 32A?

Yes because in theory a ring circuit is 2 x 2.5 in parallel which has a greater current carrying capacity than the 32A CPD

 

[ringer]

Of course. With it being a ring there is a cable either side of each accessory, and each cable is capable of carrying 20A so we actually have the capacity to carry 40A because in a parallel circuit each side carries the same quantity of current. (just thinking out loud here to make sure it sinks in - think about difference between ring and radial)
Thanks Ian - having a bit of a brain fade atm.

 

[Des 56]

each side carries the same quantity of current.

Distance also plays a part,one short leg of a ring going to high current appliances in say a kitchen, may carry quite a lot more than the second leg in the kitchen,which has to do a long tour of the house before getting back to the consumer unitIts important to try and equalise the loading for that problem to be minimised