Multiple cooking appliances.

[Soulsurfer]

Hi all,
Just looking into a kitchen refit where the customer has gone a bit excitable with the cooking side of things !

Have done lots of installs with two appliances on the one circuit but anyone know of any issue with feeding three rather than run a new circuit for say the new hob alone ?

I have an existing 32A rcbo on a 6mm twin for built in oven now and hob but new kit is an oven at 3.45kW
Combi oven / micro at 3.6kW

and finally an induction hob at 5.6kW
24.3A fuse rating on spec sheet so they haven't allowed any diversity.
Anyone fitted them with a diversity applied ? as I haven't fitted any induction before.

I'm making it a shade under 27A for the oven and combi together,

and if allowed on induction 18.7A approximately but I'm thinking likely run a new circuit from cu at the full load rating the manufacturer of the hob has given.

 

[Midwest]

when I do installs cookers hobs ,on the own dedicated circuit. but that's for me only.
with this day and age you will never know .

buzz are you sparksburntout's twin or doppelganger or even his alter ego, as he never seems to bring you to task about your atrocious spelling and grammar

 

[Soulsurfer]

Ha ha loads of them today ! Battle of Flowers on. Bongo bongo time lol, only the other Bong thing you'll find down where I surf but that's nothing to do with electrics

 

[Soulsurfer]

Ha ha loads of them today ! Battle of Flowers on. Bongo bongo time lol, only the other Bong thing you'll find down where I surf but that's nothing to do with electrics

 

[buzzlightyear]

buzz are you sparksburntout's twin or doppelganger or even his alter ego, as he never seems to bring you to task about your atrocious spelling and grammar

sorry sir !

 

[Wilko]

Don't think your following what I'm suggesting Wiko.
For the three appliances of 3450w, 3600w & 5600w, using Table A1 (applying diversity separately) I get a figure of 37.5amps (no sockets).
Or have I got my maths wrong?

You're right, but I've got it now. Your maths are correct, or I make the same mistake
The answer is quite different using Table A1 method, as its got 3 lots of 10A, vs only one lot when using Table A2. I think A2 is the one to use for this, just going by its name (?).

 

[Soulsurfer]

You're right, but I've got it now. Your maths are correct, or I make the same mistake
The answer is quite different using Table A1 method, as its got 3 lots of 10A, vs only one lot when using Table A2. I think A2 is the one to use for this, just going by its name (?).

So table A2 by using the total loads, I'm getting 41.5 A after diversity ?

 

[Dave OCD]

buzz are you sparksburntout's twin or doppelganger or even his alter ego, as he never seems to bring you to task about your atrocious spelling and grammar

Hmmm you could be on to something here, another little known fact is that Tel and Pete are actually twins.

 

[telectrix]

Hmmm you could be on to something here, another little known fact is that Tel and Pete are actually twins.

not treue. pete is 4 months older than me. that,s 18 weeks to correct the minor defects and create perfection.

 

[Midwest]

You're right, but I've got it now. Your maths are correct, or I make the same mistake
The answer is quite different using Table A1 method, as its got 3 lots of 10A, vs only one lot when using Table A2. I think A2 is the one to use for this, just going by its name (?).

According to the introduction on Appendix A, Table A1 is used to calculate the current demand for a final circuit, making an allowance for diversity. Table A2 is used for calculating the current demand of an installation consisting of a number of final circuits, also making an allowance for diversity.

The 'definition' used in both (for cooking appliances) is the same (IMO), although they are written differently.

Appendix H, and H4 advises the use of Table A1 for cooker circuits in household premises. It states that a 30 or 32 A circuit is usually appropriate for household or similar cookers of a rating up to 15kW. It also advises about the connection of two or more appliances on one circuit.

Mind you, these diversity tables were composed 'hundreds' of years ago, before induction hobs, steam ovens etc were introduced. Down to the designer.

 

[telectrix]

steam ovens? are we now regressing back to the age of steam, when things were designed and engineered to perform, regardless of accountants going for cheapest option,, broken within weeks instead of decades?

 

[Midwest]

No not steam engines, steam ovens bit like this;

 

[Rpa07]

not treue. pete is 4 months older than me. that,s 18 weeks to correct the minor defects and create perfection.

18 week wonder well that's another whole topic on the forum - out with the old Electrical Trainee in with the new!

 

[Wilko]

According to the introduction on Appendix A, Table A1 is used to calculate the current demand for a final circuit, making an allowance for diversity. Table A2 is used for calculating the current demand of an installation consisting of a number of final circuits, also making an allowance for diversity ...

Re reading the docs, I see what you mean and I'm seeing the wisdom. Table A1 title has "points of utilisation or current using equipment" and in this case there are 3 of them, so apply it 3 times

Learning everyday, cheers !

 

[Soulsurfer]

Re reading the docs, I see what you mean and I'm seeing the wisdom. Table A1 title has "points of utilisation or current using equipment" and in this case there are 3 of them, so apply it 3 times

Learning everyday, cheers !

So in your opinion Wilko would you go by 3 different applications of the 10A +30% calc and cover all (15kW) on one 50A control switch or seperate radial say for one appliance and seperate isolator of course ?

 

[Midwest]

I think if you have one existing 32A radial, I'd be inclined to drag in another. If you have a butchers at H4 OSG (described by some, as a storybook with pictures), it makes reference to isolation, and refers to reg 536.2, which I can't make sense of, but think says refer to manufacturer?