Ring Final Circuit or Radial Final Circuits?

[riveralt]

I am in the process of adding a utility room to my house. At the same time I have gutted the adjacent kitchen and intend to rewire both.

At the moment there is only one ring final socket circuit for the whole of the house, so it is my intention to remove the kitchen
from the socket circuit and run new RCBO protected circuits to both the utility room and kitchen from a new sub main.
The Utility room has the following dedicated RCBO protected circuits.
Washing machine - 16Amp.
Tumble Dryer - 16 Amp.
Lights - 6Amps (lighting circuit covers both utility and kitchen)
The kitchen has the following dedicated RCBO protected circuits.
Cooker - 32Amp
Microwave - 16Amp

In a full rewire, if circumstances (voltage drop) allowed, I would run socket radial circuits to the majority of the house and a Ring Final Circuit (RFC) for the kitchen.

However, the introduction of a utility room allows me to share the electrical load across both rooms and this raises the question of whether
or not I need/should opt for a 32Amp RFC covering both the utility room and the kitchen or run two 20 Amp socket radials one for the utility room and one for the kitchen.
The Utility Room has 5 sockets - one of which will be used for a freezer.
The kitchen has 9 sockets (equivalents) with known load of a dishwasher(2.9kw) , extractor fan, waste disposal,a fridge/freezer and electric kettle (2.9kw).
I would welcome any advice.

 

[echoes]

I opted for 32A radial socket circuit for my kitchen; thinking behind that was that 2 x 3kW concurrent loads (e.g. breakfast = Kettle + toaster) would short-term overload a 20A radial and 3x (unlikely) would certainly trip it immediately.
The 32A circuit means that 2 high-power appliances can run quite happily together, 3 (unlikely but possible) would overload, and 4 (highly unlikely) would trip it.

Although I do have dishwasher & washing machine on that circuit. Kettle usually in Cooker switch socket.

 

[Paul_C]

You've planned a dedicated circuit for the microwave oven, but I'd provide one for the dishwasher as well. That will ease the loading on any other general-purpose circuits to portable appliances like the kettle, toaster, etc.

 

[mikhailfaradayski]

Is it just an average sort of microwave or some kind of industrial jumbo jobbie?
On the face of it, a dedicated 16A circuit seems just a tad OTT

 

[JohnW2]

However, the introduction of a utility room allows me to share the electrical load across both rooms and this raises the question of whether or not I need/should opt for a 32Amp RFC covering both the utility room and the kitchen or run two 20 Amp socket radials one for the utility room and one for the kitchen.
The Utility Room has 5 sockets - one of which will be used for a freezer.
The kitchen has 9 sockets (equivalents) with known load of a dishwasher(2.9kw) , extractor fan, waste disposal,a fridge/freezer and electric kettle (2.9kw). I would welcome any advice.

I don't think it's so much a matter of advice as personal opinions, since there are clearly many ways of skinning this cat. My initial thoughts:
1...As already suggested, there's a lot to be said for putting the dishwasher on a dedicated circuit. Once you've done that, there isn't much scope for any large persistent loads to be put on your socket circuits (just short-term things like kettles, toasters etc.).
2...I might feel that a socket final circuit just for the utility room would probably be 'wasted' (what else do you envisage might be used there?). Given as already pointed out, even 2x3kW 'short-term' loads would theoretically overload a 20A radial circuit, I think I'd probably prefer 32A capacity in the kitchen. That could be a 4mm² radial circuit but (given the likely low load in utility room), and despite the fact that I'm not intrinsically a lover of ring finals, I think I'd probably end up (once the dishwaher had its own circuit) with just a single 32A ring final covering both rooms. If you did that, you'd have a very similar setup to that in my house.

Kind Regards, John.

 

[Click4]

in our kitchen we have a circuit for the kitchen sockets.

then another circuit for heavy load appliances like washing machine, dryer, dishwasher etc and things although currently no dishwasher.

not usual to have a separate circuit, but it does reduce the loading on the kichen circuit if you have heavy load appliances on their own circuit and you can rate that circuit higher than the circuit in the kitchen for sockets.

 

[ricicle]

In the ideal world it would be split up as much as possible, keeping 'leaky' appliances on seperate RCBO circuits (dishwashers have been the cause of a couple of trips in my place in the last few years - one causing the xmas day turkey not to cook in time !)