cooker connection question

[domjon]

excuse my ignorance on the subject and fear not I have no intention of attempting the job myself but I have a couple of questions regarding upgrading my cooker circuit after purchasing a new oven.

My old cooker had a 20 amp switch which needs upgrading along with the cable. Unfortunately it was fitted on a 25mm back box. I can get a 32amp switch which requires a minimum back box depth of 35mm....to save me the aggravation of spoiling the existing tiling would it be safe and legal to use a 12mm spacer plate between the wall and the new switch to get the required depth? Something like this..

http://www.amazon.co.uk/gp/product/...act_title_2?ie=UTF8&psc=1&smid=A27RN1VPVXZF5E

Also, if this is a possible solution, I notice that all the cooker connection units seem to be 45amp...is it safe and legal to connect these to a 32amp dp switch?

Just trying to figure out the easiest and cleanest way to do it before bringing in a sparky.

 

[EFLImpudence]

to save me the aggravation of spoiling the existing tiling would it be safe and legal to use a 12mm spacer plate between the wall and the new switch to get the required depth? Something like this..

Yes.

Also, if this is a possible solution, I notice that all the cooker connection units seem to be 45amp...is it safe and legal to connect these to a 32amp dp switch?

Yes, as long as they are higher than the fuse/mcb of the circuit.

Just trying to figure out the easiest and cleanest way to do it before bringing in a sparky.

Of course.

What is the rating of the fuse/mcb?
What is the rating of the new oven?

 

[domjon]

thanks for the quick reply.

the new oven is a dual fuel, gas hob with double electric oven, 4.8kw . the current circuit is 2.5mm cable so assume I need to (hopefully ) pull through a 6mm cable.

There is currently a 20amp fuse in the consumer unit so i guess that need replacing too. I'll leave all that to the sparky tbh just wanted to find the best cosmetic solution at the cooker end first.

 

[PrenticeBoyofDerry]

You oven on full load will only require 20A supply, offering diversity will also bring that down a tad. 2.5mm T&E can safely carry a maximum of 27A providing the are no de-rating factors to be calculated into the CSA of the cable, so it is possible that there will not be much alteration to the existing circuit required if on a 20A MCB.

 

[domjon]

It's all a bit over my head to be honest but if the solution is simple I'll be a tad naffed off seeing as I paid for Installation and the Hotpoint dude flat out refused to touch it when it was delivered

 

[PrenticeBoyofDerry]

It's all a bit over my head to be honest but if the solution is simple I'll be a tad naffed off seeing as I paid for Installation and the Hotpoint dude flat out refused to touch it when it was delivered

If what you have explained is correct, your existing circuit and isolation would be okay.
Hotpoint dude will likely not have scobbydoo about circuit designs and diversity! If it is not plug and play they are normally out of their comfort zone!
I come across it a lot where appliance stockist offer there own fitting service but when it actually comes to it, they are out of their depth!

 

[domjon]

well cheers anyway, I guess I better wait until the sparky has had a look before I start buying bits and bobs then. Had a quick flick through the oven manual and it does say 6mm cable and 32 amp switch, whether that's a recommendation or a requirement I have no idea.

 

[PrenticeBoyofDerry]

As an electrician we are told to follow the manufacturer's instructions, so that would always be one of the priorities to take on board!
But 4.8kW load would not require 6.00mm cable or a 32A protective device.
As far as bits and bobs, I would leave that to your electrician to sort out!
Do you have a link to the appliance you have purchased?

 

[EFLImpudence]

Hotpoint dude flat out refused to touch it when it was delivered

I think they look for any excuse not to do the work after taking your payment for connection.

I recently had a customer similarly refused because the cooker circuit did NOT have a 45A mcb.

I think it's safe to say that no domestic cooker circuits will have a 45A mcb.

 

[domjon]

As an electrician we are told to follow the manufacturer's instructions, so that would always be one of the priorities to take on board!
But 4.8kW load would not require 6.00mm cable or a 32A protective device.
As far as bits and bobs, I would leave that to your electrician to sort out!
Do you have a link to the appliance you have purchased?

http://www.johnlewis.com/hotpoint-hud61-dual-fuel-cooker/p573243

Im trying to save a few bob by getting one of the sparkys from work to do it as a foreigner so thought I'd get the bits and pieces together first if it was straightforward.

 

[PrenticeBoyofDerry]

Browsing the MI, it actually states power supply cable size of 4.00mm and a minimum 32A rated isolator!
I think they have over speced it myself.
But if you are having a new cocker circuit installed then go 6.00mm cable, this will leave you scope for a higher output in the future, it is likely that the circuit will require RCD protection and it will be deemed notifiable work, so employ a spark that can sign it off for you! Or you will have hefty fee to pay to building controls

 

[domjon]

Browsing the MI, it actually states power supply cable size of 4.00mm and a minimum 32A rated isolator!
I think they have over spec it myself.
But if you are having a new cocker circuit installed then go 6.00mm cable, this will leave you scope for a higher output in the future, it is likely that the circuit will require RCD protection and it will be deemed notifiable work, so employ a spark that can sign it off for you! Or you will have hefty fee to pay to building controls

thanks again, the guy at work has a domestic background and is still entitled to sign work off I believe so no worries there hopefully.

 

[PrenticeBoyofDerry]

the guy at work has a domestic background and is still entitled to sign work off I believe so no worries there hopefully.

It is something I would recommend that you found out, nothing wrong with having an electrician friend to do the work, but if they cannot not self cert/notify, then building controls would need to be informed prior to starting work and they will want some blood money off you. I only say this as it is a legal requirement to notify new circuits in England/Wales.

 

[domjon]

cheers, I'll double check that then