hob oven and combi microwave wiring

[harrythehat1]

Hi all, I have the following situation at home reference a kitchen refit.

John Lewis:
Hob 7.4kw, Combination micro wave oven 3.45kw and oven 3.68kw. Odd fuse sizes of 15 and 16amp (EU I guess) for the last two but with diversity they'll run at 11.5 and 11.8 amp?

I'm considering feeding all three from original cooker circuit - 6mm T&E off 32amp mcb on rcd bank of board into a 45amp cooker point then into a dual outlet. One side would feed the hob in 6mm then other side would go to a double socket to take the plugs for the m/wave and oven.

Allowing diversity I've come up with a load of 26 amp? correct me please if nec.
The loading appears ok but wondering if I've missed summink, and whether or not it wld be best to maybe put one of the ovens on the kitchen ring?
Ideally Id like to have run a new radial on a new mcb but due to tiled floors etc. almost impossible.
Help would be gratefully received.

Cheers all in advance

Harry

 

[PrenticeBoyofDerry]

Diversity allows for 15kW of output power on a 32A cooker circuit.
Which 6.00mm2 T&E cable can deal with, providing there are no other de-rating factors to calculate in concerning method and route of installation. The type of fuse protecting the circuit, could also offer a de-rating
You will however require 30mA RCD protection for any newly buried cable (buried less than 50mm without mechanical protection. NB. compliance to building regulations "part A" for depth of chases within solid walls) and any additional socket outlets will also require 30mA RCD, If this protection is not already existing on this circuit.
The regulations also state that an appliance exceeding 2kW should be hard wired.

 

[slup]

micro wave oven 3.45kw and oven 3.68kw

other side would go to a double socket to take the plugs for the m/wave and oven.

Neither of those can be plugged in... Both have a maximum power consumption that is too great - I can't see how you can apply diversity to them in that context.

You can apply diversity across the circuit, but not on a single appliance as a way of squeezing it onto a 13A plug.

Also, you wouldn't want two 13A plugs - both drawing full load - plugged into the same double socket anyway.

Personally, what I'd do is this (but I'm not an electrician and I'm sure you'll get some better advice).

Spur off the input side of the existing 45A switch and fit 2 x 20A switches. Hard wire the two ovens into these switches.

 

[riveralt]

John Lewis:
Hob 7.4kw, Combination micro wave oven 3.45kw and oven 3.68kw. Odd fuse sizes of 15 and 16amp (EU I guess) for the last two but with diversity they'll run at 11.5 and 11.8 amp?

It is very unusual for a microwave even a combi to have such a high rating.
Are you sure this isn't the combined wattage.
These ovens work on the basis of combining the various cooking methods and rarely go above 2kw when doing so. What the model name and number.
I would check to see if it comes with a 13A plug.
If my thoughts are correct then you could run your microwave from the ring final circuit.
Your other proposal for the cooker switch and dual appliance cooker connection unit - like the Click model - is okay provided your cable runs avoid insulation and any other de-rating factors.

 

[slup]

Rating plate on my combi microwave is 3.52kW so it's not out of the question.

 

[riveralt]

Rating plate on my combi microwave is 3.52kW so it's not out of the question.

Mine is a 3.48kw but it comes with a 13A plug.
As always you follow the manufacturers instructions.

 

[ban-all-sheds]

Mine is a 3.48kw but it comes with a 13A plug.

Then the manufacturer has made a mistake.

Some do, you know.

As always you follow the manufacturers instructions.

Not if the instructions are plainly wrong.

 

[slup]

Mine is a 3.48kw but it comes with a 13A plug.

UK importer whacked a plug on it to make it 'suitable' for here perhaps?

 

[riveralt]

Mine is a 3.48kw but it comes with a 13A plug.

UK importer whacked a plug on it to make it 'suitable' for here perhaps?

My mistake it is actually 3.7kw but it still comes with a 13A plug.
http://www.ikea.com/gb/en/catalog/products/00244791/
As I said earlier, like the above model, many manufacturers put the total load for these ovens when in actual fact the way they are programmed most can only use one or two of the functions combined at once.
Despite what BAS said, the OP needs to be guided by the what the manufacturers instructions say - since sometimes cutting the plug lead can invalidate the warranty. waits.......

 

[slup]

My mistake it is actually 3.7kw but it still comes with a 13A plug.
http://www.ikea.com/gb/en/catalog/products/00244791/
As I said earlier, like the above model, many manufacturers put the total load for these ovens when in actual fact the way they are programmed most can only use one or two of the functions combined at once.

In your example case, that is not true though - the manual is actually accurate:-

It correctly shows the power of each section and the 'rated' power which is the maximum simultaneous draw. In the case of your unit, it is 2800W

Bosch for example list all the power ratings of the sections and then quote a 'Connection Rating' (in the same way Ikea did above).

The 'Connection Rating' for mine says 3520W, so it can't possibly have a plug fitted to it.

Despite what BAS said, the OP needs to be guided by the what the manufacturers instructions say - since sometimes cutting the plug lead can invalidate the warranty. waits.......

Sure, if it's fitted with a plug, then plug it in.

If it isn't fitted with a plug, and the rating plate is more than 13A, then you can't put a plug on it. I'm not actually sure what we're arguing about given that we don't even know if the original posters' appliance has a plug fitted!

I'm guessing it is this one:-

http://johnlewis.scene7.com/is/content/JohnLewis/89090202pdf?

In that case, it has a 1500W grill, 1500W oven and a 1000W microwave, but lists the power required as 3400W.

So yes, the total power consumption is not the sum of all the parts, but no - it still can't go on a 13A plug...

 

[ban-all-sheds]

In that case, it has a 1500W grill, 1500W oven and a 1000W microwave, but lists the power required as 3400W.

So yes, the total power consumption is not the sum of all the parts, but no - it still can't go on a 13A plug...

"The oven is equipped with a power cable
and a plug for single phase current."

 

[slup]

Funny you should post that - I'd just noticed the very same thing.

What a joke.

So they list the 'Rated Power' as 3400W and then fit a plug to it.

And we're supposed to trust the manufacturers instructions?!

 

[riveralt]

As I keep saying - combination microwaves are programmed to work in a way that they combine their elements - but the combination of the various elements limits the total power output.
In the Ikea case it is 2800kw which is the grill and oven elements. That is them maximum rated power - hence the fitted plug.
The Lewis's model seems to be 3kw - hence the plug.
You haven't said what the make and model of your combination microwave is but I would guess it would also fall into the above category.
The only place I have seen 'plumbed in' microwave ovens is in commercial installations.

 

[winston1]

[/quote]
- since sometimes cutting the plug lead can invalidate the warranty. waits.......[/quote]

No way. They may try that on but it wouldn't wash.

 

[harrythehat1]

Fanx all for the helpful posts and input. The micro wave is model JLBIO2 product 947640685. Grill 1.55kw, conv 1.7kw and according to Mi,s needs a 15amp fuse??? Only achievable in my case by fitting a 16amp mcb in an adjacent cupboard. Question is tho feed it from the cooker isolator or spur off the ring??

Cheers all Harry