kitchen radial circuit rating?

[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? 15Amp 20Amp 30Amp ??

TIA

Gerry

 

[toasty]

If you are using 2.5mm T&E then usually 20Amp providing no derating is necessary.

I'd be tempted to run a ring though or use bigger cable as 20Amps is sailing pretty close to the wind if you are running a washing machine and a dishwasher - especially if they both decide to switch on their heating elements at the same time.

A 4mm radial will go to 30Amp I think (depending on length and again any derating due to insulation etc...) but 4mm is harder to work with and it'd would probably just be easier to run a 2.5mm ring.

What's the reason for the radial anyway?

Dan

 

[cuprager]

It will be a radial because that will be a millin times easier to install as there is an existing feed to an unused cooker control that I am going to hijack and to run a new cable would be a nightmare in my flat. So it will be 4mm to the kitchen and 2.5 to the sockets. [/quote]

 

[comms]

If you do as your suggesting you will be restricted to a 20amp fuse/mcb
due to the use of 2.5mm to the sockets.
As already said use 4mm cable from the cu for the circuit and then you can use a 32 amp fuse/mcb.

 

[Pensdown]

Not quite, it's 4mm all round, from the CU and to all sockets

 

[cuprager]

If I did it in 2.5 and hence use a 20A circuit would there be enough juice to power all of the appliances?

 

[cuprager]

I have just read the following from this site:

Radial circuits can therefore only serve a smaller area. Using 2.5mm2 cable combined with a 20amp fuse/MCB an area of 20 square metres (24 square yards) is permissible. For 4mm2 cable combined with a 32amp MCB or a 30amp cartridge fuse (a re-wirable fuse is not allowed) an area of 50 square metres (60 square yards) is permissible.

Why is a rewireabl fuse not allowed?? Its rewireable fuses that my fusebox takes!

 

[securespark]

And I would use individual outlets for the dw and wm.

That lot on one 13A outlet would overload it!

 

[RF Lighting]

Fit a plug in circuit breaker to your fuse box like this http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331832&ts=99095&id=87979

Rob

 

[Spark123]

Why is a rewireabl fuse not allowed?? Its rewireable fuses that my fusebox takes!

iirc the technical reason is because a rewirable fuse has a fusing factor of 2 and the others have a fusing factor or 1.45, hence the derating factor for rewirable fuses being the ratio 1.45 / 2 = 0.725. The rating for 4mm² flat twin and earth cable clipped direct is 37A, hence when using a rewirable fuse its maximum fuse size without any other derating factors is 26.8A, for which a 30A fuse is too large.