Installing a cooker, help!

[Evans Electric]

I think you're right evans, the hob bits will be gas.. I'm very sorry about all this confusion guys

No , no the Hobbitts are small people with big feet who live in Tolkien's Middle Earth.

Don't worry Jacksmith , we have all gone into these things wrong footed , I certainly have . Always good to take a close look at these things and avoid a costly mistake later, which I have also done.

Deke

 

[JackSmith]

as far as i can see im buying a 32a breaker, 2.5mm cable and a cooker switch.. but what about the 100a board? will i have to replace it for a higher rated board?

 

[SPECIAL LOCATION]

Hello Jack, welcome to the forum..

please take this the way it is intended..

I am sure you are more than capable to physically install the cables switchgear connect & test it to make sure its safe..

BUT you do seem to be lacking a bit of BASIC electrical science.

e.g. the total load of an oven is NOT all of the bits added up together.

Because in practice no one has every ring all the oven(s) and the Grill(s) ALL switched on to max SIMULTANEOUSLY.

This is what Theory was trying to explain about diversity.

Also with the CU ALL circuits are NOT running full power all of the time!

DO you have any regs books?

you may find it helpfull to have a read of 'Maximum demand and diversity'..

which can be found in

Appendix 1, Page 95 On site guide.

or

Appendix H, Page 177 Guidance Note 1.

Which is why the info you had said 2.5mm may be ok?

are there two ovens with thier own connecting lead from the back

or just one cable connection?

Also if it is a long run from CU to cooker issues of permissible volt drop may need to be taken account of as well.



The other point you should take account if is that a new cooker circuit comes within the remit of Part B building regulations.

OOPS!Blushing Part P building regulations (thank you ian932:| :x

so it should have a Building regs compliance certificate issued AS WELL as an electrical installation certificate.

An electrician registered with one of the approved scheme providers can self certify their work..

Otherwise you should notify the LABC first (bit like planing permission or an extension!)

Details of Part P building regs can be found in Approved document P.

Electrical safety in dwellings.

There's a link on the site somewhere to a copy that you can download!

 

[Evans Electric]

the second one looks more likely, and that's another worrying part of it.. i worked out the total of the mcbs already in which equals like 105 A, and it's a 100a board? will this be unsafe for me then to put another 20 something amps on the circuit?and i can't remember seeing any serial numbers mate

If this just a house then adding a cooker will be fine ( Diversity)

 

[SPECIAL LOCATION]

No , no the Hobbitts are small people with big feet who live in Tolkien's Middle Earth. Don't worry Jacksmith , we have all gone into these things wrong footed , I certainly have . Always good to take a close look at these things and avoid a costly mistake later, which I have also done.

Deke

Applaud SmileyApplaud Smiley:^O:^O

 

[JackSmith]

thanks, well special, it's only a 10 metre run so not too bad, and thanks for all the references!

 

[ian932]

the second one looks more likely, and that's another worrying part of it.. i worked out the total of the mcbs already in which equals like 105 A, and it's a 100a board? will this be unsafe for me then to put another 20 something amps on the circuit?and i can't remember seeing any serial numbers mate

No the load will never equate to the sum of all the MCB's, Domestic feeds are no more than 100A on the incoming for single phase.

You need to do the diversity calc mentioned earlier for each circuit and that will give you an estimated average load, its in the little red book which was suggested earlier. Get one from amazon its well worth having.

Listen I can see your keen to do this but you need to be aware that the work you are doing needs to be done by either a Part P sparky or you must get the Local Building Control Officer to check the work you do which they will charge you for.

The guy's on here can help you through the process of how to install etc, but be carefull not to get ahead of your ability on this job. Do you know someone who can work through the job that is part P? they could mentor you on the job. If not do it properly through the LBCO and that way you have a job you can use in the future if you went for your own part P registration.

 

[ian932]

The other point you should take account if is that a new cooker circuit comes within the remit of Part B building regulations.

OMG :O:O when did that come out

Ok Ok :coat

 

[JackSmith]

yea thanks ian, well i've got a mate who is part P who is going to go over it for me when it's done, i just don't want to be ringing him with all these daft questions i've been askin ha

Edit: Just to confirm finally, a 32 a breaker and 2.5mm cable is the correct choice now?

 

[a1]

Jack, Calm down.

There is no such thing as a daft question, only daft people for not asking them.

This forum really is "a forum with a difference!".

No-one will "extract the urine" out of you.

Regards,

Admin.

 

[JackSmith]

thanks admin, can anyone just confirm that is correct for me? from the 2 ovens i get this info:

large oven : 2.5kw and 2kw,

small oven : 800w, 700w, and 1.4kw

So the max power is 2.5 + 1.4k = 5.9 kw right? which gives me 21 A? so.. 32 a breaker and 2.5mm cable, correctomundo?

 

[Evans Electric]

Not knowing how the oven works ( some prevent you from switching the full load) I'm saying a 4mm cable on a 32 a MCB and a 32a or 45a DP switch at the cooker.

 

[Andy™]

so.. 32 a breaker and 2.5mm cable,

absolutly not. 2.5 is only rated to 27A under ideal conditions. you need at least 4mm for a 32A MCB

best would be 32A with 6mm, gives some room for expansion

 

[JackSmith]

ok, thanks alot

 

[jibspark]

on the other hand you might get it out of the box and find a plug on the end of the cable........ job done.

 

[Andy™]

on the other hand you might get it out of the box and find a plug on the end of the cable........ job done.

but it should still be on its own circuit... probably best to still install 32A 4/6mm circuit now though and put a socket instead of outlet

 

[jibspark]

but it should still be on its own circuit... probably best to still install 32A 4/6mm circuit now though and put a socket instead of outlet

fair point, does anyone know why they all come with plugs on the end, never understood it.

 

[Andy™]

so you can plug them into a cooker circuit that has a socket for an outlet... and under 16th, there wasnt anything to say you cant use ring (although common sense should apply and not have everything loaded on one side of ring)

17th says something about over 2KW should be on dedicated circuit

 

[JackSmith]

i checked this first time i looked at it, it's nothin but a pre-fixed internal wire comin out to a connector block inside a cover

 

[Theorysparky]

fair point, does anyone know why they all come with plugs on the end, never understood it.

because thats they way the cooker designer has rated the product

plug and play

so are we saying to ignore the manufacturers instructions and use 4mm

does that not invalidate the manufacturers warranty ????

shower/rcd thread comes to mind :^O

i wonder if theses designers ever read the regs ??