Ring main circuits appear to be radial at consumer unit.

[Jurassicspark]

Blimey- how big is your home?

I suppose EFL's consumer unit is in the hallway and the kitchen he is referring to is extended from the rear.

My CU is in the store room which is very close to the kitchen but I am planning to move it in the future.

 

[opps]

I suppose EFL's consumer unit is in the hallway and the kitchen he is referring to is extended from the rear.

My CU is in the store room which is very close to the kitchen but I am planning to move it in the future.

I was being flippant, sorry. The fact that EFL said that it was less than 40m away from the CU, left the possibility that it might, for example, be 39m away.

 

[EFLImpudence]

 

[Why Not Indeed]

The implication being that 39m would entail a pretty large house.

 

[EFLImpudence]

My CU is in the kitchen and of course I only have 16A radial circuits.

 

[JohnW2]

Australia based its Electrical Regulations largely on those of the UK.
.... Recently this has been changed.
Existing 2.5 mm² Radial circuit installations (protected by 20 A Circuit Breakers or RCBOs) may continue in operation.
However, if any "work" is done on any such 2.5 mm² circuit,
the MCB or RCBO must be changed to a 16 A rating.
Any New Work protected by 20 A MCBs or RCBOs must be in 4 mm² cable.

Do the Australian regs not accept that the current-carrying-capacity off a cable varies according to how it is installed?

In the UK, 2.5 mm² T+E radial installed by 'Method C' (e.g. clipped to surface or buried in plaster etc.) can be protected by a 20 A OPD (or a 25 A one if available), since the CCC with that installation method is regarded as 27 A.

 

[JohnW2]

In the UK, 2.5 mm² T+E radial installed by 'Method C' (e.g. clipped to surface or buried in plaster etc.) can be protected by a 20 A OPD (or a 25 A one if available), since the CCC with that installation method is regarded as 27 A.

I might have added that, conversely, in the UK a 4 mm² radial is only allowed to be protected by a 32 A OPD if it is installed by 'Method C' - but what you say may imply that, in Australia, a 32 A OPD may still be acceptable (although it wouldn't in the UK) even if it were n installation method which was 'worse' than 'Method C'. Is that the case?

 

[flameport]

What period do radial circuits come from?

Everything from the 1880s to today.

The 30A or 32A ring final circuit using 7/.029 or 2.5mm² sized conductors as described in BS7671 and it's predecessors was designed in the 1940s for a specific set of circumstances that applied at the time and were considered to be applicable for the forthcoming decade or two.