Hi folks this is my first ever post to the forum, which looks to be very useful indeed...thanks in advance to any responders...

I am putting in a new kitchen and am getting conflicting advice on size of cable needed for the cooker circuit...6mm or 10mm ???

The existing wiring looks like 6mm or similar circa 1958 I guess when the house was built. (actually its maybe thicker but definitely not 10mm).

As I am retiling and putting in a new cooker and cooker switch I have the opportunity to replace all the wiring.

The oven is a basic built under fan oven, nothing fancy, rated 2.5KW (= 10 amps?)

The hob will be a ceramic hob rated 5.8 KW max (= 24 amps?)

The first 2 meters of the cable will be buried in the wall, going via a cooker switch of course and then there is a 17 meter run to the main board, which will be in the ceiling under floor boards. (but very easy to replace as its a bungalow so effectively the wiring is in the loft). The main board currently has a 35 amp MCB in the "cooker" position, but presumably could be changed if necessary.

My "tlc-direct" catalog says 6mm is rated at 40 amps so that should be ok except maybe a voltage drop oon the 17 meter run?.

My local lectrical retailer says "we always use 6mm for cookers unless its a big range jobby"

And then there is the diversity rule which I understand says that with cookers I only need 10Amps but 30% of the balance...so that would mean I need to cater for 10A plus 30% of 24 amps which is 17.2 Amps so I am well within the 6mm capability.

Yet I have this feeling nagging away that to be on the safe side I had better put in 10mm wiring.

As this is a small bungalow I don't think we will ever put in one of those massive cookers so I think I need only cater for the current (haha) set up.

Any advice would be most welcome.

Although I have no formal qualifications i am pretty experienced at domestic wiring, but as you can see I have niggling doubts occasionally!!! Rest assured that when I have finished I will call in an electrician to check everything over.

Re 1958 ish wiring...it's actually grey sheath and feels ok, but its coming out anyway! I guess it might be newer that the original build stuff. I just need to know whether its best to replace with 10mm or whether that's overkill and 6 mm would be ok. Cheers.

You're doing th right thing in planning it all out properly, as this is what the local building control body will need to see with the plans on your preliminary notification.

What district are you in? and I'll send you a link to more specific information for your local council.

On the subject of load, will your Isolator by the cooker have a 13A socket incorporated in it?. You'll need to do some extra working out if so.

Generally I'd say you've a golden opportunity to upgrade the safety of the installation while the decorating is being done. However if the building control costs look prohibitive you may decide to just run some large oval conduit to a blanked off back-box to allow the upgrade to be done at a later date by a 'Self Certifying' electrician. Without the need for disturbance to the new decor.

If you adopt the latter approach I'd recommend a full periodic inspection of the property as the existing wiring sounds like it may be getting on a bit.

Thanks to all responders for the replies. Beanzy..we are Windsor and Maidenhead.
And re the rest of the wiring, most seems to have been replaced in a piecemeal fashion. It was checked by a qualified electrician who installed new consumer unit and some wiring in 2003. But I plan to do same again after this latest work.

[quote author=braychurchmouse  link=1106669586/0#0 date=1106669586]

I have the opportunity to replace all the wiring.

[/quote]

You don't need to inform the BC to replace wiring for a single circuit. It will cost you at least £60 if the BC is informed.

Would'nt take the advice from B&Q staff, but spose it depends on your position  

Thanks beanzy, I appreciate your thorough reply, it certainly gives me a far better understanding of the new regulations than I have been able to get from a call to the council.

So i have decided actually to put 10mm in, to "future protect". And as safety is the prime concern I always believe over-provision is best and the extra will cost me only a few pounds more. Also as the isolator switch has a 13 amp socket anyway I think I needed to rework the calcs, even though it is only for a low power extractor hood 200watts i guess regs say i should allow full 13amps, in case someone sometime plugs in a kettle!

Now I was wondering       as I lay in the bath, taking a hypothetical situation concerning a similar situation that a "friend" is in....supposing if in 5 year's time the secret police discovered that I (oops i mean the "friend") had done this wiring and hadn't got approval....if the "friend" said that the work was done in 2004 not 2005, would that keep him out of prison?

That is assuming the house hasn't burnt down already because of "amateur" wiring done in the rest of the house by "qualified" electricians...that I am replacing/rectifying as quickly as possible and which i plan to get throughly checked when finished,  by a qualified electrician (a different one!).  

Re actual choice of 10mm cable, interesting range of alternatives for 25 meters....£30 for bog standard and £37 for Pirelli (Screwfix +postage)....£47 from TLC. Guess which I chose?

Well of course if the work in 'the other house' were begun before January 1st, and finished before April 31st he wouldn't have to notify anyone. Of course it would be a good idea to get a real proper spark to do Periodic Inspection and Test on the existing installation before April, as this would show all circuits which existed at the time the test was done. an prove nothing had been done outside the scope of PartP (time-wise).