switchin of kitchen appliances

[nabby68]

hi fellas,
I plan to have the following in my kitchen,

Fridge freezer on a 16amp radial with switching above worktop also, dishwasher and washing machine on ring and both with switching above worktop and finally single built under oven and hob on a seperate ring again both switched. My question is that would they need to be all switched by fcu,s bearing in mind that they will all be fused at the plug?
Thanks

 

[holmslaw]

..

 

[Lectrician]

Oven and hob on a seperate ring? Can you explain exactly what you plan to do here?

 

[nabby68]

Sorry lectrician, maybe you misunderstood me, i meant oven and hob on seperate ring from rest of kitchen, hope that clears it up.

Use correctly sized isolating switches

would these be 13amp switches?

 

[ban-all-sheds]

Two large loads on a ring final is unlikely to be a good design, why not use a radial?

 

[Lectrician]

What rating is your Hob? Gas or Lecky?

Again, two items on a single ring doesn't make sense to me.

 

[rebuke]

You want 20A DP switches for the isolation. Incidentally, since nobody else have said it, you should be aware that if in England or Wales this work is notifiable under Part P of the building regs, so you either need to have it done by a suitable electrician (check they're on www.competentperson.co.uk), or if doing it yourself you'll need to notify your LABC in advance and pay their fee...

 

[nabby68]

What rating is your Hob? Gas or Lecky?

my hob is gas but will need to be plugged in for the ignition and the oven is rated to 2.3 kw

Two large loads on a ring final is unlikely to be a good design, why not use a radial

Hi BAN, i take your point and maybe i will switch to a radial but could you explain why this is unlikely to be a good design? thanks

You want 20A DP switches for the isolation. Incidentally, since nobody else have said it, you should be aware that if in England or Wales this work is notifiable under Part P of the building regs, so you either need to have it done by a suitable electrician (check they're on www.competentperson.co.uk), or if doing it yourself you'll need to notify your LABC in advance and pay their fee...

yes, i am aware of part p and will be informing LABC

 

[ban-all-sheds]

my hob is gas but will need to be plugged in for the ignition and the oven is rated to 2.3 kw

You can ignore the load of a spark igniter.

So why do you want a dedicated circuit for a single 2.3kW appliance?

Hi BAN, i take your point and maybe i will switch to a radial but could you explain why this is unlikely to be a good design? thanks

Because you'll have what is essentially a single point of utilisation, so your ring will actually be a parallel circuit, and unless you make both legs of the ring the same length the load on each leg will be unbalanced.

Plus you simply don't need a ring for a single 2.3kW appliance...

yes, i am aware of part p and will be informing LABC

What will you say will be the way you'll comply with Part P?

Have you checked to see if your LABC is one of the ones that doesn't play by the rules? By the time you've paid just their fee it may be borderline as to whether it's cheaper than getting an electrician, if they are going to make you also pay for one to inspect your work it's virtually guaranteed to be more expensive to DIY.

 

[sparkwright]

why not run a radial for the oven and gas hob in 6.0 mm t+e?

you can use a 32 A mcb and run cable to a 45 A isolator switch, then run the cable to two single sockets.

a cable of this size may prove useful for any future changes eg an oven upgrade. by using a 32 A mcb you shouldn't need to replace it if you get a bigger oven/hob.

no real reason why the gas hob can't be wired to the main kitchen ring.

 

[nabby68]

Because you'll have what is essentially a single point of utilisation, so your ring will actually be a parallel circuit, and unless you make both legs of the ring the same length the load on each leg will be unbalanced.

Plus you simply don't need a ring for a single 2.3kW appliance...

i take your point and will switch to a 16amp radial. And i am just in the process of contacting LABC to see wat they would charge to come and inspect the work.

 

[ericmark]

The whole idea of the ring circuit is to save on copper and to allow many sockets with fused plugs to be used from same supply because it is in essence two parallel circuits of unequal lengths the rating is reduced from 21A per cable to16A per cable to allow for uneven load. There are times where because of cable size two parallel circuits of equal length are used but not normally in domestic. (see exception below)

The radial system is therefore used for cookers, showers, immersion heaters etc. Also because lights is such a low load with normally a 6A max because of ceiling rose rating but with cable rated well above this a radial is still used.

Up to 13A one can fuse at the outlet either in a plug or fused connection unit but FCU seem to be only available to 13A so after that large boxes are required to house the fuse or overload so hob, Shower etc. are normally fused or have MCB in the consumer unit. Any appliance over 2Kw has to be carefully planned and not just plugged into a ring circuit although there can be a carefully planned ring circuit.

For example you could use a grid switch from a ring to power washing machine but in the main the appliances are all switched in same grid switch unit so no real point in ring main. Although feeding with 6mm then radiating out to individual sockets can present a problem getting wires into the holes in grid switches so here is one place you may get two parallel circuits of equal length.

The rules say you must fuse down when changing cable size (current carrying capacity) within 3 meters of the change so from grid switch to sockets should be less than 3 meters, the same when fitting a spur. However this is often not strictly adhered to. This is where you have a problem as although a skilled person can enter a non-compliance and get away with it as a DIY’er some one else needs to pass your work and unless it’s A1 you have no real way to know if the guy will pass of fail what you have done.

Main thing is all electrical work needs inspecting and testing and meters for latter are not cheap. So an electrician want to extend a ring, he takes reading first then works out if he can do it or not. Without these reading you could over step the mark.

The LACB route is really designed so skilled electricians can do domestic work without being registered not really for true DIY. With a load of reading and hiring test equipment you may be able but I think your very brave.

Or fools rush in where Angles fear to tread?

 

[nabby68]

thanks ericmark

For example you could use a grid switch from a ring to power washing machine but in the main the appliances are all switched in same grid switch unit so no real point in ring main. Although feeding with 6mm then radiating out to individual sockets can present a problem getting wires into the holes in grid switches so here is one place you may get two parallel circuits of equal length

The ring i was planning for the oven and hob would be equal length as the cale from the consumer unit to the appliances would be returning on exactly the same route. But as BAN said it seems more sense to have them on a radial as the hob would be negligible.

Also planed to have the washing machine and dishwasher on a ring, this would also be both legs of equal length