Diversity Factor

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I did not agree with the logic. 32A is greater than 16A - simple. It is a capping mechanism - in this instance safety will not be compromised, as all wiring back to the main fuse and beyond will not overheat capable of 100A. Put too much on the 16A rings then the mcb's trip. I know the mcb's have overload.

 
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If the occupiers plug in and turn on all their equipment at the same time, it makes no difference whether the load is spread among fifty circuits or four. They all go through the same company fuse and the same meter; and the same landlord's fuse if there is one.

If you wanted to limit peak loads, you could go for an economy 7 type tariff, and timers to use the UFH and the immersion heaters mostly overnight or at different times when other appliances will mostly be turned off; and get a heat pump tumble drier.

Other tumble driers are heavy power users and may run for several hours continuously, or nearly so.

BTW I'm slightly surprised your tenants aren't allowed a dishwasher. you could have a downrated induction hob.
 
Thx. Considering all you write. Washer/dryer, combination oven. Rooms of UFH will have timers on all rooms.
 
It is 36A max, may be 30A when all assessed accurately, ballpark for now. Induction hob with small electric oven under.
What ratings are the induction hob and oven?
Trying to get the oven and microwave all in one unit (combination oven) so both are not on at the same time.
The main idea of combi-microwaves is that one does have both microwave and conventional cooking happening 'at the same time'.
Two 16A rings as opposed to two 32A rings, will create a cap for sure.
As I've said, not really. If two '16A rings' provide enough power for what is needed, people would generally not plug in more appliances if they were '32A rings'. As I've also said, even 'two 16A rings' could allow best part of 50A to flow for an hour of so - and 16A circuits are much more likley to be run 'near to their total capacity' than would be the case if they were 32A ones.
3kW immersion.
There goes another ~13A.

I really think you are worrying unnecessarily. There are countless installations out there, including those with electric showers, electric cookers, tumble dyers and immersion heaters (plus all the usual 'plug in' bits and pieces), running off 60A or 80A DNO service fuses, and it is incredibly rare for those fuses to blow as a result of overload, even on Christmas Day.

Kind Regards, John
 
One ring in the flat which will take the TV and other low current appliances.
One ring in the kitchen which will take the immersion, maybe a kettle and toaster on the worktop. Immersion is off the ring as it is difficult to get its own cable to the kitchen.
Oven and induction hob off 40A mcb.

I has to conform to regs. It will be checked. I know it will safely work, but will it get the nod?
 
One ring in the flat which will take the TV and other low current appliances.
One ring in the kitchen which will take the immersion, maybe a kettle and toaster on the worktop. Immersion is off the ring as it is difficult to get its own cable to the kitchen.
Well, the immersion alone will use up most of the 16A. Add on a kettle or toaster (or almost anything else) and the circuit will be substantially overloaded (and certainly not 'capped' to 16A). ... and what about the microwave and washer/drying - where exactly are they to be supplied from - surely not the "16A" circuit already supplying the immersion and kettle/toaster etc??
Oven and induction hob off 40A mcb.
What are their ratings - i.e. how much of that 40A will they be using?
I has to conform to regs. It will be checked. I know it will safely work, but will it get the nod?
You surely must realise by now that if you go around adding up all the loads you've mentioned you'll end up with an answer well over 63A, and that remains the case no matter what OPDs you chose to use for the various circuits.

As I said before, I really think that you are worrying unnecessarily. If people thought like you, I imagine that few domestic installations would 'get the nod'!

Kind Regards, John
 
Putting the immersion on the kitchen ring was only decided today, as access for a dedicated cable is poor, so 32A it has to be.

The overload on mcb's is frightening. Even 2.5mm ring with a 6A mcb will still work quite well running a 3kw kettle.
 
The induction hob and oven on the 40A cable are not yet decided. I am assuming average kW for these.
 
I suppose it would help to understand the project and responsibilities. Are you doing work for a third party? If so who is responsible for notification, and who will sign the EIC?
 
You surely must realise by now that if you go around adding up all the loads you've mentioned you'll end up with an answer well over 63A, and that remains the case no matter what OPDs you chose to use for the various circuits.
That is why we have diversity calulations. Using the diversity calcs, I gave a vid on them, it was exceeding. Hence my concern, hence using some ways of capping.
 
I suppose it would help to understand the project and responsibilities. Are you doing work for a third party? If so who is responsible for notification, and who will sign the EIC?
This is at the design stage of a renovation. We do not need electricians at this point, just what the limits are with work arounds if the limit is being exceeded. Or dropping parts, like the electric UFH then using a wet system with a thermal store, heated overnight (very expensive installation), or the likes. A large thermal store cylinder will take space hence a redesign of the kitchen. A diversity calc is not difficult to do giving the framework you can work within.

One option to for a work around is a Tesla Powerwall battery to get around the problem, and cheaper bills. This charges up overnight using a low tariff. There is space for the Powerwall on a terrace. Prefer to keep the installation rather standard.
 
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The overload on mcb's is frightening. Even 2.5mm ring with a 6A mcb will still work quite well running a 3kw kettle.
It might 'work' (and, if it did, it would also 'work' with 1mm² cable) - but that's because a 3kW kettle would take a minute or two to trip a B6 MCB, and the kettle may well have 'boiled' before that happened.
 

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