Cooker and induction hob on one circuit?

[Jackuzi]

Hi all,

I'm doing the kitchen and changing the oven from an all in one elec oven/gas hob to a built-under elec oven and separate 4 ring induction hob. Oven is rated at Nominal power: 3kW 13A and hob is 5.9kW 32A

Oven http://www.smeguk.com/Catalogue/Product/SC485N-8.aspx

Hob http://www.fagor.co.uk/60cm-zone-induction-hob-with-touch-controls-p-46.html

The current circuit to the cooker is via a DP switch (guessing 45A) that is on a 32A MCB at the CU. Would it be okay to run both cooker and hob on this circuit? What needs to be changed/checked. I'm thinking change the MCB for a 45A MCB and wire in the hob the the DP switch, with a separate 13A FCU for the cooker also wired to the DP switch?

I also think I'd have to check the cable used to wire in the current circuit. It should be 6mm I think.

Thanks

 

[ericmark]

Method #100 will only allow 34A on 6mm cable so you will not be able to safely change the MCB to a larger one.
The problem is induction hobs have a boost so diversity does not work in same way as with resistive elements.
However 37A on a 32A MCB will likely hold. The only real problem is if it relies on cooling fans as if it trips then it could over heat.
The problem is what ever we say makes no difference it is down to guy signing paperwork. Since Part P it would be uneconomic to DIY so all up to guy doing the job.

 

[davelx]

Method #100 will only allow 34A on 6mm cable .

And you're assuming Method #100 has been used based on what, exactly? It's just as likely to be method C.

OP - can you describe the length and path the cable takes from the consumer unit to the outlet, including the surroundings it runs through?

 

[ban-all-sheds]

I'm doing the kitchen and changing the ... gas hob to a ... induction hob.

Why are you downgrading appliances as part of doing up a kitchen?

 

[Jackuzi]

The hob in question does not have a boost function in it's list of features. It does have fan cooling though.

I'm not sure of the path from the CU to the current hook up point. It is currently sited on an internal wall and I would like it relocated to the opposite wall (external). The run from the CU (located in the garage at the front of the house) goes straight up into the ceiling of the garage. To get to the cooker point it needs to cross a cloakroom, utility room and then gets to the kitchen.

Untitled

• Jackuzi
• 16 Aug 2010
• 1

I was originally going to buy a larger induction hob made by Fagor but it required 2 feeds one @ 32A and one @ 16A and I didn't fancy having to have addition wiring from the CU. I would also have to change to CU as I don't have any spare capacity. [/img]

I will have to get someone in to take a look but I like to get my head round these things before a professional comes in to assess. I think you get a better result if you look clued up yourself

 

[Jackuzi]

I'm doing the kitchen and changing the ... gas hob to a ... induction hob.

Why are you downgrading appliances as part of doing up a kitchen?

What do you base that comment upon?

 

[ban-all-sheds]

Nothing is as good as gas for a hob.

Removing a gas hob and replacing it with one which is not gas is a downgrade.

 

[davelx]

OK - what we're looking for with regard to the cable run is whether it is running in free air, clipped to a wall or joist, over, under or through thermal insulation, etc, - including for what length and how thick the insulation is. These factors affect the current carrying capacity of the cable.

6mm cable clipped direct to a wall or joist with no thermal insulation can carry about 47A, so depending on how the cable is run, it may be possible to uprate the MCB.

The total length of the cable is also important with regard to voltage drop and loop impedance limits.

PS: I tend to agree with BAS about gas hobs being better -- except when simmering, especially if there is any draught, when the thermal inertia of the electric hob gives a more constant heat input. Personally my ideal would be dual fuel (I cook quite a lot so this is based on first hand experience)

 

[Jackuzi]

Nothing is as good as gas for a hob.

Removing a gas hob and replacing it with one which is not gas is a downgrade.

BAS - Sorry, I understood your statement I just wondered what you were basing your statement on ie. personal experience, customer experience, Professional reviews etc. Are you also taking into account that I'm talking about an Induction hob and not a standard ceramic hob.

I have read close to a hundred recent reviews from mostly non-professional but some professional users and they all seem to really rate induction for response, economy, ease of cleaning etc.

I would appreciate if you could expand further, thanks.

Davelx - Thanks for educating me, I had no idea about how the way the cable was run could affect its performance. I guess if I find the cable to be 10mm then I'm laughing. The house was built in 98 by the couple we bought it off so hopefully they spent a little bit more on that cable run.

 

[ban-all-sheds]

Personal experience, and the fact that, notwithstanding professional reviews, gas is almost the universal choice in restaurant kitchens.

Also I don't want to be restricted in my choice of cookware, told that I can't shake pans while I'm cooking, have to fiddle around with matches or lighters when flambéing, have to find another way to char the skins of peppers and aubergines etc....

 

[1john]

The biggest pro of having a gas top and an electric bottom is that all your eggs arn't in one basket, should your electric fail you can still boil water for a cuppa and fry some bacon for a butty, if the gas goes then you can always grill the bacon and feel a bit healthier about yourself.

 

[ban-all-sheds]

Blimey - you must be rich if you can afford bacon that's OK to fry.....

 

[ericmark]

I looked at your link it states:-

4 induction zones

Front right 2.8/1.4 kW (180 mm diameter)
Front left 2.8/1.4 kW (180 mm diameter)
Back right 2.8/1.4 kW (180 mm diameter)
Back left 2.8 / 1.4 kW (180 mm diameter)

With the duel marking 2.8/1.4 I assumed a boost!

As to Gas v Induction the fact that local councils will not permit the use of gas for disabled and promote the use of induction because of the advanced safety features does point to induction being better.

Gas also heats the room more and makes it very hot work for the cook.

The idea of putting heat into the room rather than the food has an obvious flaw. The induction hob on the tests I attended did boil a pan of water faster than gas which was the first time I had ever seen electric beat gas and I was impressed. I did not however take note of wattages and BTU outputs and since the demo I have noted many different sizes of induction hob.

And cost of gas hob with air conditioning v induction hob then induction hob is cheaper. And in general gas makes a bigger bang then electric!

However this does not help you and you have to decide if to take the chance that the MCB will trip and cause the hob to over heat as a result. I would think it is unlikely and likely you will be able to run it all off the 32A supply but not to raise the point would have also been wrong.

It seems two problems with induction. Using pans only just big enough so slight movement off centre switches off the hob. And spilling liquid on the touch controls which switches everything off. Some have magnetic knobs.

I understand why commercial kitchens don't use induction hobs. Consider the power needed with 4 or 5 in a kitchen likely would need complete re-wire. However with health and safety being talked about if the kitchens were forced to keep to within working temperature permitted in offices ect then the cost of extra air conditioning would out weigh the cost of supplies for induction hobs.

 

[xdave]

Just to add to what ericmark has said, my experience of cooking with an induction hob is...

Pros:
- You can shake the pans around as much as you like. Any decent hob will work with as much as 30% of offset because they know exactly where the pan is.
- Stick oil in a cold frying pan and turn on the heat to full - it is at stir fry temperature in about 6 seconds. Good pans have a slightly rounded bottom which expands flat when heated (not that it matters with induction because it doesnt need contact with the hob) however you can see the bottoms of pans moving as soon as you turn on the induction zone.
- Decent hobs have an automatic function whereby you can set a simmer/cook temperature and have it bring the contents to the boil then automatically maintain the lower temperature with boosts as needed (for example if you add a handful more veg into a boiling pan). Makes cooking very easy, and with the suitable cookware makes steaming large items such as whole fish easy because you can span across 2-3 zones.
- Some hobs can also detect when a pan is boiling dry and adjust the temp accordingly.
- Induction compatible pans are more common than most people think. Anything with an iron content can usually be used, although some stainless steels are too low. If a fridge magnet sticks to the pan it can be used. Cast iron can be used (cast iron items that claim they can't is usually down to not having an enameled bottom which protects the hob, but can still be used if you put a sheet of kitchen roll under them).
- If something boils over you can just ignore it because the hob surface is cooler than the pan. (Normal glass surface rules apply - if it has sugar in it wipe it off hot or it attacks the glass.)
- Cleaning. Cleaning. Cleaning! A quick wipe with a damp cloth after cooking and then a dry off with kitchen roll is all that is needed. No fiddling around removing the top of the hob and cleaning around the burners.
- Flat surface extends your work areas.
- 90% efficiency. Boils water in 1/2 the time of gas and uses about 40% of the energy to do so (assuming the electricity comes from coal or nuclear).
- Safety around children or elderly people. No burnt fingers or moments of "can you smell gas?"

Cons:
- If you stir fry forget a wok unless you want a dedicated induction unit with a rounded surface. Most hobs are flat and will work fine with pans held about 20mm off the surface, but any more and it won't work. Saute pans are the next best thing and remember you can shake them around.
- Higher equipment cost than gas.
- Bas doesn't like them.

 

[ban-all-sheds]

You can shake the pans around as much as you like. Any decent hob will work with as much as 30% of offset because they know exactly where the pan is.

When I say "shake", I mean shake with it sitting on the hob, whether the pan is cast iron, enamelled, s/s, aluminium, whatever, without damaging the hob.

Most of the other "Pros" I'm not going to comment on, they're of no particular interest to me - a bit like Hill Descent Control on off-road vehicles, I don't agree that automation is a good substitute for proper equipment and knowing how to use it, but not everyone feels the same.

Induction compatible pans are more common than most people think. Anything with an iron content can usually be used, although some stainless steels are too low. If a fridge magnet sticks to the pan it can be used.

I quite like hard-anodised aluminium pans and roasting dishes, and as I said, I don't like being told I can't use them any more.

Cast iron can be used (cast iron items that claim they can't is usually down to not having an enameled bottom which protects the hob,

I refer you to my comment about shaking pans.

Cons:
If you stir fry forget a wok unless you want a dedicated induction unit with a rounded surface.

I do stir fry with a wok, and my hob has a wok burner with a ring to cradle a traditional round bottomed wok.

Like I said - I don't like being told I can't use something...

Higher equipment cost than gas.

I hadn't noticed. Decent gas hobs don't come cheap.

Bas doesn't like them

Because of all the cons that apply to me, as identified in my earlier post.

Me not liking them isn't a valid reason for others to avoid them, but I think it's worth me pointing out what I see as drawbacks in case it makes someone go "ooh - I hadn't thought of that" before they make an expensive purchase they end up regretting.