Another Cooker/hob Question

[Hayemaker]

Hi guys

I have a current cooker thats 8.4KW  on a 32A mcb run in 6mm from C/U to 45A wall socket then 6mm from that to Cooker control unit at low level .. then 6mm from there to the appliance.

I am installing a New Oven + Hob  which are 4.8KW (double Oven)  and 6.6KW(Hob) respectively  totalling 11.4KW ..  Hob will be 1.6metre from the C/U  and oven will be 2.5Metre from the C/U .. in trunking behind kitchen cabinets.

Now if my calculations are correct including diversity its something like this    11.4KW/230v= 49A   49A - 10A = 39/100x30=11.7+10 = 21.7A (PLEASE correct me if i'm wrong on this)
 

As i already have an existing circuit on a 32A Mcb  can i hardwire the oven and hob into a 45A Easyfit Dual Appliance Connection.

Or do i have to run a new circuit for the Hob using 6mm from C/U through to a FCU off the existing cooker point and hardwire hob into the new fcu 

I KNOW this is notifiable under Part P but as i cannot afford to get someone in to do it for me  I am doing all the dogwork myself and getting someone in to test + sign off.

Im a level 3 student at college but have not had the "on Site" experiance most people have had  so i know a little bit about kitchen circuits BUT am not 100% on it which is why i am seeking advice from you professionals.

 

[Blue Duck]

Have you done corrections for trunking? should be okay on a 32a breaker unless it is an induction hob.

 

[Hayemaker]

im going to go another method now .. going to run a new supply for the hob and leave the existing cooker supply ready for the new cooker to go straight in .. for the hob its going to be a 32A mcb   6mm t&e from c/u to 45A cooker switch next to the existing cooker switch from there to a cooker connection unit located to NEAR (not behind,below or above to where the hob will be situated. then i can use the 6x1.5 mm heat resistent cable that came with the hob and hardwire that into the new cooker connection unit..   this covers me in every way .. oh the cable shall be clipped behind the cabinets NOT in trunking (although because they are now to be seperated i could put it in trunking.  

And no it is a Ceramic Hob

(product info  -  Hotpoint CRM641DX Built-in Ceramic Hob - Black )

 

[Murdoch]

Have you done corrections for trunking? should be okay on a 32a breaker unless it is an induction hob.

Whys that? I'm curious!

 

[Blue Duck]

I had read somewhere that you couldn't apply diversity to induction hobs either that or I dreamt it :lol: after another read it's clear that you can apply diversity to inductions but should check MI's for the OCPD.

My Bad sorry.

 

[Blue Duck]

Found a thread on another forum where there are several suggestions that diversity shouldn't be applied to an induction hob.

http://www.theiet.org/Forums/forum/messageview.cfm?catid=205&threadid=61339&enterthread=y

Confused.org

:C

 

[SLIPSHOD & SLAPDASH]

My view on it is, diversity was brought in when everyone had a cooker and you will never be pulling the full load current of each ring, grill, oven etc due to the stats kicking in and allowing for the time characteristics of the ocpd. A seperate oven today, single or double is still the same but a seperate hob, especially some of these huge multi ring/specialist odd heating things that can have 6 or more rings including induction hobs could pull the full rated current so diversity should not be applied.

What I am not sure about is due to the speed induction hobs heat up, are they designed to operate within the tripping time characteristics of a mcb ?

 

[Blue Duck]

I do a lot of free standing cookers courtesy of social services and Argos.

They usually work out at 16a with a socket on the CCU you could probably stick a plug on them as they won't get used anyway, just a box ticking exercise.

Never done an induction hob hence my lack of understanding, but from what I have read they pretty much use full whack most of the time as the emphasis is on speed rather than heat.

Funny that a 7.2kw is exactly 30a at 240v

 

[Murdoch]

We have a Rangemaster dual electric oven & grill & 5 x induction rings. Total pull on full wack "is" a theorectical 17.7KW

Rangemaster say 6mm cable on a 32A breaker

I installed 10mm cable as I was doing a rewire!

 

[Hayemaker]

i am having a seperate double oven (oven and grill)(4.8KW)   and a hob (6.6KW) about half a metre from the oven ...  i intend to keep the existing cooker circuit for the Double oven  and then for the New hob circuit use 6mm from the new 32A mcb in the C/U right through to termination of the hob Via a 45A cooker switch then a 45A cooker connection unit ... this means i'll basically have two cooker circuits in my kitchen from the C/U .. both on 32A mcb's  ...  as i am only a level and have not YET passed my Part P i cant sign it off myself but a friend of mine said he would do it for £45 thats for testing a previous swa from C/U to shed and also this new kitchen circuit .. £45 for test & Cert for the circuits you have worked on only He said .. so i am unsure as to wether the local council will be satisfied with this.  he is a member of the elecsa  and part P approved contractor so i'm taking his word for it .. but at "mates rates" i could not really ask for much more for the 45 quid he charging me.

I was originally planning on putting them both appliances on a 45A dual easyfit appliance connection unit and the one single 45A cooker switch. then upgrading the current 6mm from cooker switch to the C/U with 10mm  and then upgrading the current 32A mcb with a 40A/50A mcb BUT this came with a few problems so thought it be easier to put in new circuit on a 32Amcb for the hob.

as i said i am NOT a full electrician as yet and am currently finishing my level 3 so this is still a learning curve BUT the two seperate 32A circuits may seem overboard to most but i rather be safe than sorry. 

PLEASE correct me if ANY of what i suggest seems wrong as i take criticism kindly as advice.