Electrics in new kitchen

[nabby68]

Hi Fellas,
I plan to install a new kitchen in my girlfriends house which is soon to be our house after i sell mine! Anyway first of all, all the sockets in the house are wired on a 30amp ring with also a 30amp radial for the cooker and the present cu has plug-in type fuses so i think a new cu will be in order.

In the new kitchen i plan to have a fridge freezer on a 15amp radial swithed above the work surface, a dishwasher and washing machine on there own 32amp ring also both switched from above, oven and hob and extractor hood on another 32amp ring (oven will be no more than 3kw and hob will be gas) both oven and hob switcable from above the work surface. The rest of the existing sockets in the kitchen will be left as they are and used to plug in only portable equipment eg toaster and mirowave.

I also plan to have under cabinet lighting and plinth lighting both spured off the existing ring main.
As you can see there seems to be a lot of switches and have thought about grid switching but the oven and hob are on one side of the kitchen and the fridgefreezer, dishwsher and washing machine are on another side so one side would be more than 2m away from any grid switching.

Iwould like to be able to split the exisiting ring in the house but trying to find out where the ring goes from downstairs to upstairs may course too much disruption.

Your thoughts and ideas on this matter would be appreciated.
thanks

 

[PrenticeBoyofDerry]

It's fine putting the fridge freezer on a separate circuit make it a 20amp radial in 2.5 using flexishield cable then no RCD needed. So no nuisance tripping so food in freezer thawing out.
Again D/W and W/M on a radial not on a ring.
The oven if less than 3kW can be plugged into the socket circuit.
This part p notifiable work as it's in he kitchen, so building controls will need notifying.
As you are having a new CU installed then all becomes notifiable work, I assume you are employing an electrician for the install if so they will help you in your design and make sure all the inspection, testing reports are made out and and installation certificate given.
Useful Link
//www.diynot.com/wiki/electrics:part_p

 

[nabby68]

It's fine putting the fridge freezer on a separate circuit make it a 20amp radial in 2.5 using flexishield cable then no RCD needed. So no nuisance tripping so food in freezer thawing out.

thankls prenticeboy
am i right in saying that the 17th edition gives provision for radials that have a single appliance on them such as fridgefreezer for it not to be rcd protected? also what are youhr thoughts on grid switches and the ammount of potential switches i will have?

 

[RB2004]

Hi as far as I know,

All circuits buried less than 50mm without mechanical protection require RCD protection, even a fridge freezer radial, but this would be overcome with an RCBO, instead of putting it on the same RCD as other circuits.

"a dishwasher and washing machine on there own 32amp ring also both switched from above"

if it is just these 2 items, a radial should be sufficient providing the correct loading is worked out and appropriately sized cable is used. As said previously as well, 20 Amp should be sufficient for just the 2 appliances, 32 Amp would be overkill.

Regarding the switched spurs, again as far as I know (could be wrong).. you cant have more spurs on a circuit than sockets.

"It is not permitted to have more spurs than sockets on the ring, and it is considered bad practice by most electricians to have spurs in a new installation (some think they are bad practice in all cases)."

http://en.wikipedia.org/wiki/Ring_circuit

for the undercabinet lighting, and plinth lighting if your taking it off the socket ring.. remember to fuse it down.

 

[plugwash]

All circuits buried less than 50mm without mechanical protection require RCD protection

Afaict if you want to run a circuit without RCD protection it has to be ONE of the following

* Not concealed (e.g. surface clipped or in surface conduit/trunking)
* More than 50mm deep (not normally practical due to structural condiserations)
* in an installation under the supervision of a skilled of instructed person (cue arguments over what exactly that entails)
* provided with mechanical protection (the general opinion is that capping of any form and plastic conduit do not provide sufficiant protection)
* enclosed in earthed metal that is adequtely rated to be a CPC for the circuit (usually steel conduit)
* wired in a cable type with a built in earthed metal layer that is adequately rated to be a CPC for the circuit (e.g. SWA, pyro, some but not all of the screened fire resistant cables, flexishield)

Sockets intended for general use and below a certain current rating (I don't remember what offhand but it's something like 32A) must be RCD protected. Afaict the general opinion is if you clearly label a socket and put it behind an appliance then it counts as not intended for general use.

I disagree about putting both a washing machine and a dishwasher on a 20A radial. At their peak many such appliances draw the full 13A our sockets are rated for and it is only a matter of time before thier cycles line up. Especially as most moden appliances are cold fill only (which i've never been convinced is a good thing because it means the water gets heated with expensive leccy rather than cheap gas or off peak leccy but the manufacturers seem to like to do it that way). If using regular switches I'd suggest a 4mm radial but if using grid switches a ring may be easier to wire (from what i've heared terminating 2x4mm conductors in a grid switch terminal is a PITA).

 

[nabby68]

Thanks fellas for all your replies so

plugwash wrote:

disagree about putting both a washing machine and a dishwasher on a 20A radial. At their peak many such appliances draw the full 13A our sockets are rated for and it is only a matter of time before thier cycles line up.

so, would a 32a ring be overkill for this?

thanks

 

[PrenticeBoyofDerry]

plugwash wrote:

disagree about putting both a washing machine and a dishwasher on a 20A radial. At their peak many such appliances draw the full 13A our sockets are rated for and it is only a matter of time before thier cycles line up.

Fair point, I should have put 32A radial in 4mm but ring in 32A 2.5mm will do the job too.

Thanks fellas for all your replies so
so, would a 32a ring be overkill for this?
thanks

your answers is above, is it a DIY or you getting an electrician in?

 

[Aragorn84]

you could use a 32A radial?

Personally, i'd be tempted to put the oven, hob and extractor on its own radial, the fridge freezer on its own as you described, then create a kitchen ring main for the washing machines and the portable appliances?

 

[nabby68]

thanks for all your replies. just one other thing, i wish to have plinth lights but most of the lights ive seen plug into a socket and i wish to operate them from the existing lighting circuit, is there a way round this that anyone can suggest?

 

[PrenticeBoyofDerry]

Would it not be easier to take a spur from a socket outlet, using a Switched fuse connection unit to down fuse it to the rating for the lights and also using that as functional switch?

 

[nabby68]

Would it not be easier to take a spur from a socket outlet, using a Switched fuse connection unit to down fuse it to the rating for the lights and also using that as functional switch?

i suppose that is an option but would have liked to have a normal two gang switch on the wall to control the main kitchen lights and also the plinth lights.

On a seperate point is it acceptable to have my freezer on a 15amp radial but not rcd protected bearing in mind the 17th regs and does this depend on the cable being at a depth more than 50mm or protected mechanically?

 

[PrenticeBoyofDerry]

You can have circuits without RCD protection they do have to comply to regulation stated in BS7671:2008. and it's not as straight forward as the cables being buried in a wall to a minimum depth of 50mm.
The socket must be marked up specially for use of that appliance, these sockets can be bought.

The lights will be dependant on the manufactures instruction, but can't see why not.

 

[nabby68]

also, because i am having my dishwasher, washing machine, fridge freezer oven and hob all switched from above the work surface are these items only to be plugged into a single gang socket?

 

[PrenticeBoyofDerry]

also, because i am having my dishwasher, washing machine, fridge freezer oven and hob all switched from above the work surface are these items only to be plugged into a single gang socket?

You can put doubles there but a bit pointless as the switches will isolate the double socket and as it is used to isolated a designated appliance on that outlet, so singles make sense.

 

[flameport]

i wish to have plinth lights but most of the lights ive seen plug into a socket and i wish to operate them from the existing lighting circuit, is there a way round this that anyone can suggest?

Fit a single unswitched socket under the units behind the plinth, and supply this from the lighting circuit via the light switch.