Question for the " ELECTRICUTIONISTS"

[middi]

As mentioned in earlier post I am in the process of fitting ( my wife's !!!) kitchen units, appliances etc..
The high level electric oven is rated at a max consumption of 2.4 kw, requires a 1.5mm cable with a current rating of 13 amp. ( from the installation instructions)
By my calaculation ( derived by checking kw at the bottom of our electric kettle !! ) all I need is a 13 amp plug and connect it directly into one of the existing 2.5 mm ring main plug circuit, as far as I am concerned if the kettle has worked well for the last 6/7 years so should the cooker.
I know from past experience that with electric cookers electricians install separate circuits directly to the consumer units, but always presumed this is done simply to cover themselves ( and keep within the law) in the event that the occupier may want to install a 6 kw or even 10kw all electric cooker/oven combinations.
Will I be breaking any rules, and what would you do.

(Any " with no prejudice" views will be wellcome)

Middi

 

[Penners]

With no prejudice ( :wink: ):

I agree with you. Fully installed electric cookers - if you're using the oven and several rings at the same time - can be consuming 6 - 8 kW or so. They therefore need a special circuit to accommodate this.

If your unit has a maximum consumption of 2.4 kW (10 Amps), then this is less than many electric kettles. If it were mine, therefore, I would do as you propose and power it from a 13A plug in a ring main socket.

But I'm an amateur in such matters. With a bit of luck, one of our electrical experts will appear and support or explode my opinions!

 

[Lime]

The old convention of having a large separate feed to a cooker is not required if you are only fitting an oven.
However you need to know that any electrical work in a kitchen is notifiable (BEFORE ANY WORK is started) to the LBC under part P of the building regulations.

 

[MdB]

As Lime says, electrical work in the kitchen needs to be signed off.

The difference between an oven and a kettle is that the oven is likely to be on longer than the kettle so that there is a higher chance of there being something else on the same ring switched on at the same time. If for example you had your oven (10A) an electric heater (13A) and your kettle (13A) all running from the same ring main then there is a good chance the 32A fuse will trip. In most peoples kitchens, getting up to this limit is unlikely but I recently had to stop my dad from switching on three kettles in his kitchen at once to deal with an influx of people at a party.

In your case, I would run a separate cable back to the consumer unit if I could but wouldn't worry too much if I couldn't do so easily and just spur it off the ring main (meeting the appropriate regs for spurs).

An important thing to note is that the thickness of the cable you need to run to your oven doesn't depend only on the load it will take. It also very much depends on the environment it will installed into. If it is run next to any form on insulation or next to other cables for example then the required cable size goes up. There is a set of regs detailing some of this. As a matter of principle, I always use a minimum of 2.5mm for anything connected to a ring main (sometimes larger!), 1.5mm for lighting mains and 1mm for connection to lights and switches.

 

[middi]

Thanks for the reply chaps.
I think you have confirmed what I suspected.
In an ideal world I would have liked to run an indipendent supply to the consumer unit but, as some of you have noted, in this instance it maybe an overkill. It should present no problem plugging the oven in the existing 32a rated 2.5 mm ring main consisting of max allowance of 8 double plug sockets.
The original electrical installation was fully approved and I do not see the reason why I should not use any 13a rated appliance into any socket which I choose to use.

I fully understand that it would be unethical ( and overloading ) to plug a 2/3 kw appliance in every socket in the 32a circuit.

middi

 

[Zebra]

Although electrical work in a kitchen requires a Part P certificate, I'm not sure whether you meant you will connect the oven by means of a plug to an existing socket outlet - which wouldn't need a certificate, or creating a new fixed outlet on the ring - which would. I'd definately agree with MdB about using 2.5mm cable for connecting fixed spurs to a ring.

 

[middi]

All I intend to do Zebra, is to plug the 13amp plug from the oven ( as per oven instructions, 13 amp with a max 2.4 kw consumption) into an existing plug socket in the kitchen main ring circuit. The ring main is designed to accept 13amp plugs and all done according to regulations.
Whilst I am reasonably comfortable at working out current and wattage loading in a circuit, I was not quite sure if ,by some obscure regulation, I would need an indipendent supply from the CB board regardless of current load. Whilst I accept that any appliance on it's own circuit would be " good practice" I do not think that the current loading of my oven would justify running an indipendent circuit. I know that the oven will only load the existing circuit as much as an average electric kettle and therefore quite safe.

( I know a lot of things but also accept that some people know better :wink: )

Middi

 

[MdB]

Sounds sensible to me Middi.

 

[Zebra]

If wiring a house from new I think the ideal is to put in a cooker circuit wired in 6mm or even 10mm cable, with a cooker switch within 2m of the cooker position as per the regulations, and install not only a cooker outlet point on it which would take an electric cooker of some 8-9kW or whatever, but also a socket to take an oven on a 13A plug. Then both are controlled by the cooker switch. However, I'm not sure that the regulations are totally clear about what needs to be controlled by the cooker switch, where you have separate oven and hob. Perhaps I need to read the regulations book again! You certainly do get ovens connected via a 13A plug to the ring, and I'm not aware that this is against the regulations in that you then don't have a switch with which to isolate the oven. As far as I'm aware, cooker switches are meant to isolate the hob in the event of a chip pan fire or something, and ovens don't have to be on them. Perhaps others will be more clued up!
Anyway, I reckon that you'd be fine to install your oven on the ring via a 13A plug, and in that case you wouldn't need to get a Part P certificate.

 

[robgil]

So you have the oven , kettle , toaster , microwave, fridge/freezer, toastie maker , extractor , etc etc all on the kitchen ring?
If it were me I would want to reduce this if I could, or certainly not add any more to it..

 

[middi]

I have a toaster, a washing machine, a tumble drier, a dishwasher, a fridge/freezer, a small freezer, a kettle, a microwave, food mixer and God knows what other electrical gadget my wife stores in the draws of the existing "temporary" kitchen all of which operate from the same 32 amp 2.5mm wiring ring circuit. Nothing has blown up or tripped yet. ( admittedly I was keeping an eagle eye on it at christmas time when every appliance appeared to be on a the same time !!!). The electric oven has it's own circuit and rated at 3.2 kw.

In the " new" kitchen the tumble drier, freezer and washing machine will be omitted and "swapped" by the new 2.4kw oven, these will remain in the " old " kitchen together with the " old" 3,2kw oven. As mentioned in other topic post, and in case the TWO ovens breakdown at the same time, a rayburn woodburner cooker range will be installed as requested by my beloved. ( I have not had the heart to tell her I think she has flipped, and to prove my point, we have only just finished eating supper, beatifully cooked by the local TAKEAWAY!!!! ).

THe things we do for love.

Middi

 

[robgil]

You are a lucky man Middi , Ms Robgil wants the moon on a stick and never seems to be able to understand why she cant have it.

 

[Me!]

In a situation like this where someone may wish to make wiring changes in a room, and that room is not a kitchen yet, but may by some strange coincidence suddenly get converted into a kitchen fairly soon after the wiring changes have been made, .......... which rules apply?

 

[Lime]

The same rules apply.
There is a lot a householder is allowed to do.
However running new circuits and renewing old circuits but running them using a different route are both notifiable.

 

[Penners]

You are a lucky man Middi , Ms Robgil wants the moon on a stick and never seems to be able to understand why she cant have it.

She's got one better than that, Rob. She's got you.

If you manage to convince her of that, let me know how you did it, would you?

 

[Zebra]

So you have the oven , kettle , toaster , microwave, fridge/freezer, toastie maker , extractor , etc etc all on the kitchen ring?
If it were me I would want to reduce this if I could, or certainly not add any more to it..

Well yes having all that on at once would trip the circuit breaker, but then that is what it is designed to do.

 

[robgil]

Shes trying her best to get rid of me. :lol: It's like war of the roses here today , I know where she can put her moon on a stick!! :lol:

 

[Flyfisher]

So you have the oven , kettle , toaster , microwave, fridge/freezer, toastie maker , extractor , etc etc all on the kitchen ring?
If it were me I would want to reduce this if I could, or certainly not add any more to it..

I agree. There's a difference between a safe installation and a practical one - try plugging in three electric kettles into a ring main and you'll soon see the difference. It's perfectly safe, in an electrical sense, because although the three 13A kettles will exceed the maximum capacity of the ring main, the 30A consumer unit fuse/MCB will trip to protect the wiring and prevent overheating. So, perfectly safe but not very convenient.

Of course, not many people use three electric kettles at once. Indeed, not many people plug an appliance into every socket of a ring main. But kitchens are a bit special in this respect in that they tend to have the highest concentration of high-power appliances in the home AND it is very common for all of them to be used at the same time. So, to avoid 'nuisance tripping', it might be wise to split things over more than one circuit.

This sort of thing is called 'diversity' and I believe there are specific guidelines somewhere in the regulations, or maybe the notes to the regulations, but I'm a bit rusty these days.

 

[Zebra]

In a situation like this where someone may wish to make wiring changes in a room, and that room is not a kitchen yet, but may by some strange coincidence suddenly get converted into a kitchen fairly soon after the wiring changes have been made, .......... which rules apply?

The problem would come when you came to sell the place, or if Building Control were to need to see a certificate for the wiring once the new kitchen was finished, I think you'd get raised eyebrows if you said "well when we wired that it wasn't a kitchen!"

 

[middi]

Common sense views from everybody. As FF points out it maybe not be a question of the wiring being illegal but more a case of practicality. The wiring is legal, done mostly by myself, but wired to the consumer, tested and certified by a qualified electrician. A max of 8 double wall sockets per 32a ring circuit.

As to selling the property, and I have no plan for this, my view has always been that if someone wants your house that much they will buy it with or without certificates ( bar planning of course). After all if the seller is alive and able to sell it is highly unlikely that he/she has been electricuted by dodgy wiring.

Middi