what size wiring

twomill

i wish to install a new electric oven/hob in a new area of the kitchen.can anyone tell me what size or guage of wiring i'll need? total load should be no more than 4kw. i want to run a completely new supply from fuseboard so what size of fuse will suffice? many thanks for your help

fishdog

A 6 square T & E protected by a 32 amp B type MCB would be standard practice. 4kW sounds small to me, a 25A MCB would do in your case. Even though a smaller cable would be OK with a 4kW load I would go with the 6 sq. so that if you ever get a more powerfull cooker you are OK and do not have to wreck the place again!!

No offence, but if you are asking these sort of questions you have not got the experience required to carry out such a job. This requires connectiong to a distibution board and even that requires experience and training to know things such as, can this board safley take this increased load?? Which neutral bar should I use??

However the information given above should assist you in knowing if your electrician is doing the job correctly.

Stoner

fishdog wrote: »

. 4kW sounds small to me, .

Me too, unless it's one of those light ovens that are available for apartments, where a 20 Amp MCB protecting a 2.5sq.mm T+E cable is used.
you're always better off with the larger cable fused down anyway.
a model no of the oven would help confirm an exact rating

davelerave

i started using a 47mm dual flush box and a separate 6sq and 2.5 supply to cover the various options and separate switching of oven and hob.

Stoner

davelerave wrote: »

i started using a 47mm dual flush box and a separate 6sq and 2.5 supply to cover the various options and separate switching of oven and hob.

I guess that's the best approach to have, covers many options

knighted_1

ok - i install ovens hobs etc for a living - you should run 6 sq from your fuse box to switch -you will prob not be able to connect 6 square in to the back of your new oven as all standards have changed -if its a single oven its normal for 2.5sq while whirlpools come with 1.5sq as standard -if its a double oven etc 4sq -6sq while most hobs now are around 4sq but some are as low as 2.5 -

what sparkys wont be informed of is all new appliances are more energy efficient hence lower wattage and consumpsion

i installed a top spec miele double oven recently and 2.5sq was the recomended feed

times are changing -but if youre not sure of anything get someone in ,it will be safer in the long run

fishdog

you should run 6 sq from your fuse box to switch -you will prob not be able to connect 6 square in to the back of your new oven as all standards have changed

What many of us do is simply crimp on a lug or a pin to the 6 sq. cable and then it fits in to even a small connection no problem at all.

what sparkys wont be informed of is all new appliances are more energy efficient hence lower wattage and consumpsion

You would be surprised what we are aware of!!
Cookers, hobs, ovens are almost purley a resistive load, the lower the resistance the higher the current, the greater the required current carrying capacity of the cable. If the current carrying capacity goes up the cable size may have to be increased.

if its a single oven its normal for 2.5sq while whirlpools come with 1.5sq as standard

Most electricians would not be happy having a 2.5 sq. cable on any greater than a 25A B type MCB.

Be warned, I have seen some people using a 1.5 flex yet its only "protection" is 32 amp MCB. This would not be safe under fault conditions. The idea is that the protective device operates before the cable fails. A 1.5 flex can not safley take 32 amps and a 32 amp B type MCB will generally not trip even with 40 amps flowing through it!! Even a heat resistance flex would be in a dangerous condition after prolonged exposure to a current of this magnitude.

Remember the effiency of the cooker is irrelevent when it comes to calculating cable size!
My experience has been that high end modern cookers, hobs and ovens are of a higher rating, such as Neff. Also Many people are now buying double ovens.

knighted_1

fishdog -a lot of new installaions i have seen are on no more than 20a mcb
and this is easily changed upwards if need be

2.5 sq is rated to 27 amps so in theory and practise this is ok

what i have seen is this ,20a mcb 6 sq to switch ,6 square to fixed plate/junction box ,then two 2.5sq cables feeding oven and hob .

providing load on the two is less than 20a ,then there is no problem that i can see

domestic appliance installation would be a minute part of a sparkys job and there are other people out there with more up to date knowledge direct from manufacturer/distributor

if a sparks installs an oven or hob or cooker and doesnt downrate the mcb from 35A to a suitable lower amp wants to ask himself questions

fishdog

fishdog -a lot of new installaions i have seen are on no more than 20a mcb
and this is easily changed upwards if need be

Yes, there is nothing wrong with that. I never suggested that there was.

What I said was:

Most electricians would not be happy having a 2.5 sq. cable on any greater than a 25A B type MCB.

what i have seen is this ,20a mcb 6 sq to switch ,6 square to fixed plate/junction box ,then two 2.5sq cables feeding oven and hob .

When you talk about reducing cable size (from 6 to 2.5 for example) it is good to mention that the MCB should be reduced in rating also. Some people that read this forum might not know that.

I never suggested that you did something wrong.

providing load on the two is less than 20a

It does not prove that. In fact a B type 20 amp MCB may not trip, even at 25amps in reality.

domestic appliance installation would be a minute part of a sparkys job and there are other people out there with more up to date knowledge direct from manufacturer/distributor

As sparks we are quite good on cable sizing, protection of cables, connecting and have recieved 4 years training at a minimum as well as a recognised qualification. You may know your stuff with appliences, but you can not argue that we as sparks are not qualified to connect domestic cookers!!

if a sparks installs an oven or hob or cooker and doesnt downrate the mcb from 35A to a suitable lower amp wants to ask himself questions

That depends mainly on the load and the cable (as well as sevral other factors). I connected a 3 phase 21kW pizza oven not long ago! BTW 32A is the stsndard MCB for cookers in Ireland, although this may vary.

Stoner

fishdog wrote: »

BTW 32A is the stsndard MCB for cookers in Ireland

Ooch lol

twomill, are you sure that the load will only be 4KW, as discussed you have a particular requirement, and with the details of the oven and hob we will give you the correct answer

We are just discussing generalities here at the moment

twomill

it's an electric oven with a gas hob, that's the reason for some of the confusion.
many thanks all the same for the info
regards
twomill

Stoner

This could be great news, many gas hobs dont need an electrical supply, the igniters are mechanical and built into the hob. The electrics for a gas hob take little or no load and you could even take a switched fused spur from a socket ( seperate cables to the board are always best, but this is a very small load, the gas does all the work)
anyway first thing to check is does it actually need an electrical supply, or does it spark by simply pushing the control knob down

then use a 6sq.mm cable to feed the oven, this will future proof the installation, you can drop the size of the MCB to 20 Amp if the oven requires so little load, but if you are going to run something in there is no point in limiting yourself to a 2.5.sq.mm cable IMO.