kitchen radial circuit

[Cuprager]

Hi All,

I am going to install a radial circuit to feed all of the sockets in my new kitchen, there will be 5 double sockets in total with two being used only for the extractor hood and the cooker sparker, one will have a washing machine and dishwasher permanently and the other two are counter top ones for general use.

What rating should the radial be - it will have its own fuseway all to itself?

TIA

Gerry

[Dave Plowman (News)]

Radials are normally 20 amps - which might just be marginal with an electric kettle and toaster on as well. Why not just bite the bullet and make it a ring? Perhaps with a spur for the cooker hood and the sparker?

BTW, it might be easier to wire the hood off the lighting circuit.

[Christian McArdle]

It should be a 32A Type B MCB/RCBO ring. However, depending on the size of the kitchen and other appliances that may be installed in the future (dual fuel cooker, microwave, tumble dryer), it may be better to run two 32A circuits (one 32A MCB radial for fixed appliances and one 32A MCB/RCBO ring for general purpose sockets). However, with only 5 double sockets, it suggests a small kitchen where you may be able to justify a single circuit.

Your fridge/freezer should be fed from its own circuit that does not have

30mA RCD protection (it may require 100mA RCD protection if you have TT earthing). Any general purpose ring in the kitchen should have RCD protection. It is not required for a fixed appliance circuit. It is also technically not required if the sockets wouldn't be useful for garden equipment (i.e. lawnmowers). However, this is a silly rule and you should aim to provide RCD protection anyway.

Christian.

[Cuprager]

Thanks for the useful advice. If I was to install a 32A radial circuit what type of cable should I use to feed the sockets etc? 4.0mm t&e ??

TIA

Gerry

[David Hansen]

On Mon, 24 Apr 2006 12:23:21 +0100 someone who may be Cuprager wrote this:-

Why have sockets for these? Switched fused outlets are the thing.

So, roughly 26A for the washing equipment and another 13A for a kettle. Allow some diversity and estimate the maximum demand.

What do you think? The standard options are a 20A radial, 30/32A radial or 30/32A ring.

Note the cable sizes for each and the effects of influences (such as installation method, grouping and thermal insulation) which you have not told us about.

I suggest the last one, mainly because of cable costs. The middle one may be more suitable, in some circumstances.

Lastly, do you intend to do this work? In the free world, or in John Prescott land?

[Cuprager]

Hmm, what happens if all of the above are on in a freak washing and feeding moment?

I intend to use the existing radial wiring that feeds an unused cooker control - I will drop down the fuse rating accordingly and use the correct rating of cable in the kitchen (what will that be - 2.5mm or

4.0mm ?) The cable will then either be surface fastened or buried in the plaster depending on where it goes. The cable will not be bunched together with other cables but may be fastened to the wall beside other existing lighting cables.

Its going to have to be a radial as the flat that I live in would be a nightmare to install a new ring.

I intend to do the work myself - this is a DIY forum :-)

Thanks

Gerry

[Christian McArdle]

I wouldn't run a 32A radial circuit to all the sockets, as the cable is harder to deal with. 2.5mm cable in a ring is much easier. If you do want to run a 32A radial for the fixed appliances, I would use 6mm. A calculation may allow 4mm. However, 6mm has better volt drop and much better earth loop impedence characteristics. Run the 6mm to a suitable junction box near the required sockets. Then run 2.5mm to single sockets, via a DP switch if required. The 2.5mm is fine on a 32A circuit, provided it only runs one accessory (to provide overload protection) and the length is short (to provide short circuit protection).

Christian.

[Owain]

20A if you wire in (minimum) 2.5mm cable. 32A if you wire in (minimum) 4mm cable.

Cable sizes may have to be increased if derating factors apply, such as rewireable fuse, ambient temperature, running through insulation, grouping, etc.

And I would put the WM and DW on separate single sockets or FCUs, not sharing a double socket.

Owain

[David Hansen]

On Mon, 24 Apr 2006 15:15:16 +0100 someone who may be Cuprager wrote this:-

Depends on the nature of the overload and its duration. If there was no allowance for such things then the electricity system would be unaffordable as many cable sizes would be quadrupled. Kettles and toasters are not usually on for long periods.

What size of cable is the current circuit? What type and rating is the protective device?

That rather depends on the location, but can be the case in some circumstances.

[Cuprager]

I havent measured the cable but it is very large! The protection is currently a 45 Amp rewireable MEM fuse.