Max demand for double oven and hob

[HappyHippyDad]

In addition....

Ps.. Well done with all your correct, yet perhaps OTT brackets in your OP

Pps.. I'm not quite sure of your maths though.

Remember the 30% is only taken from the 'excess' current.

e.g if the oven is 4.8kW = 21A, the 30% is only taken on 11A of that as you have already taken off 10A as a fixed amount. So diversity for that one appliance is the first 10A + (30% of 11A) = 13.3A

 

[Ray Pooley]

In addition....

Ps.. Well done with all your correct, yet perhaps OTT brackets in your OP

Pps.. I'm not quite sure of your maths though.

Remember the 30% is only taken from the 'excess' current.

e.g if the oven is 4.8kW = 21A, the 30% is only taken on 11A of that as you have already taken off 10A as a fixed amount. So diversity for that one appliance is the first 10A + (30% of 11A) = 13.3A

Thanks for the response.

Brackets are a great way to get around BODMAS. Makes life easier. For me at least.

Ok. "in excess of". I didn't factor that in. That's true. I forgot to do that. But I think you'll find that the maths is fine in my calcs given the values I have used.

This post does seem to illustrate that there can be a variation in this calculation depending upon how you view the arrangement. My original question was about how you interpret the rule. The one appliance vs the two appliance perspective.

Anyway, whatever comes out of the calculation I think if I get up on Christmas day, put a pan of vegetables on each of the hob plates, a turkey in the oven and turn everything on the actual demand is going to be about 45A for about 5 minutes. Nevertheless the existing B32 should be ok. It's class B so it trips at a minimum of 96A.
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In case anyone is wondering, I have an electric oven and a gas hob. I am pulling the gas hob out and replacing it with an electric hob. Hence the question.

 

[telectrix]

Gas Hobs Rule--- OK. only reason to swap for leccy one is:
1.you want an induction hob as it's maybe more efficient.
2. your missus wants one coz next door just bin bragging about theirs.

 

[Ray Pooley]

Gas Hobs Rule--- OK. only reason to swap for leccy one is:
1.you want an induction hob as it's maybe more efficient.
2. your missus wants one coz next door just bin bragging about theirs.

Induction hob. Now there's a thought.

 

[pirate]

I only recently got to grips with BODMAS...that's why my biomass boiler is 18x bigger than I needed.
Induction hobs...there is no finer way to cook...IMHO. Especially if you have no gas supply.

 

[Ray Pooley]

I only recently got to grips with BODMAS...that's why my biomass boiler is 18x bigger than I needed.
Induction hobs...there is no finer way to cook...IMHO. Especially if you have no gas supply.

Perhaps. But I just checked. They're twice the price and I'm not sure my man pan is compatible. They reckon they are but I'll keep it old school. Might get a second hand one even. See how it goes.

 

[Pretty Mouth]

As for diversity, I would treat them separately. It doesn't make sense to me to treat them as one item as they are not. If one item is on full there is no limiting device to make sure the other is not.

It does make sense to treat 2 (or more) cooking appliances as one when applying diversity. After all, diversity relies on there being several 'elements', with not all of them being on full simultaneously. The more parts there are, the more valid diversity becomes.

You make a very good point about the internal power management of some cooking appliances though. In these instances, I believe it is correct to use the 'sum of the parts' and apply diversity to that, rather than applying it to the appliance rating.

For example, supposing the OP's hob was a 4 zone induction hob, each zone rated at 3.2kW, but internal power management limits it to 5.5kW. The sum of all the zones is 4 X 3.2 = 12.8kW, this is the figure we would use to calculate diversity, not 5.5kW.

 

[pc1966]

Brackets are a great way to get around BODMAS. Makes life easier. For me at least.

Better to have redundant brackets in an expression than the wrong answer from not remembering precedence-order perfectly!

 

[Ray Pooley]

It does make sense to treat 2 (or more) cooking appliances as one when applying diversity. After all, diversity relies on there being several 'elements', with not all of them being on full simultaneously. The more parts there are, the more valid diversity becomes.

You make a very good point about the internal power management of some cooking appliances though. In these instances, I believe it is correct to use the 'sum of the parts' and apply diversity to that, rather than applying it to the appliance rating.

For example, supposing the OP's hob was a 4 zone induction hob, each zone rated at 3.2kW, but internal power management limits it to 5.5kW. The sum of all the zones is 4 X 3.2 = 12.8kW, this is the figure we would use to calculate diversity, not 5.5kW.

Just watched the JW video you posted. It's a pretty recent one. He produces great vids. I have watched loads of them. That's the way to go.
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Better to have redundant brackets in an expression than the wrong answer from not remembering precedence-order perfectly!

I'm a retired computer programmer. Thirty years in the biz. Brackets in formulae are essential when writing code.