Have come across a 16A Ring Final

[Mikegh]

I would chanlenge you on that As many consider primary benefit of RFC to be secondary earthing (or connection route) should the cable gets disconnection or damage along the route.
While I am not a fan of RFC myself another of the benefits greater then its maximum fuse size is that in the event of lose or limited connection the other leg will have lower resistance and as such the resulted arcing is likely to be far lower to none, where on radial where there is no parallel path all current would have have to flow through it.

Dunno

Id say its hard to argue that capacity is the main benefit

'Secondary earthing' , lower efli and volt drop would be Secondary benefits I reckon

 

[Dustydazzler]

I always thought the old 32a RFC was to save cable and so that an entire houses sockets could be wired in 1 big circuit.
This was when you probably only had 7 maybe 8 sockets in an entire 3 bedroom property.
Many old houses you work on often still have the old 3036 board with just 3 circuits , Lights , Ring and Cooker

 

[Mikegh]

I always thought the old 32a RFC was to save cable and so that an entire houses sockets could be wired in 1 big circuit.
This was when you probably only had 7 maybe 8 sockets in an entire 3 bedroom property.
Many old houses you work on often still have the old 3036 board with just 3 circuits , Lights , Ring and Cooker

They'd be related wouldn't they

Material costs and capacity

2 sides of the same coin I reckon

 

[Intoelectrics]

Hey!!!

I object to that, I haven't got frizzy hair!

I've got no hair, however my brain is fried!

 

[telectrix]

I've got no hair, however my brain is fried!

sure you not going through a sex change?

 

[Intoelectrics]

sure you not going through a sex change?

Who knows, these days with all the gender identities I'm not sure.

 

[EricMark]

There are two limits to length of cable in ring finals, one is enough current should be able to flow to operate the magnetic part of the MCB/RCBO and the other is the voltage should not drop below the limits.

The latter is rather hit and miss, there is no hard and fast rules, we are told it is worked out as 20 amp in centre as 12 amp even spread, so 26 amp is used to calculate cable length and with 2.5 mm that works out at 106 meters.

But with a large home, by dropping to 16 amp you can have 180 meters of cable, personally would look at lollipop idea and use even 10 mm if required to a twin cooker outlet plate and form the ring final from that. But there is no hard and fast rules, I have in the past used 6 mm to junction boxes and spurs to each socket in a warehouse where the 24 foot drops from false ceiling in the refrigerated room would have cause problems with volt drop for the cleaning equipment to be used in the cheese store.

Although designed for homes, ring finals are used elsewhere, but in the home the advantage is reduction of cable used, and number of RCBO's required to allow many sockets which can have the 3 kW load without causing it to trip.

In the main swapping to less than 32 amp is because of an error somewhere.

 

[SparkySy]

Has the circuit been down rated due to the installation of the cable running through thermal insulation? I've seen a couple like this where a large amount of cellotex insulation was used!
Sy