Max Demand calc for new supply

[leestaf]

HI Guys

I have a 8 flats and 2 retail units due to be built soon and i am trying to work out the Maximum demand for each of the flats and the 2 shops so the supplier can ensure a large enough mains supply.
The Retail units are to just have a supply to a distribution board, the shop is not too large and without any definite future spec given to me i would assume a 16mm 4c SWA 3P+N would be adequate.
The flats are of differing sizes but i have done the calcs and worked out the correct sizings for the space to be heated.
If i allow diversity for the final circuits and taking the storage heating at 100% the total max demand is between 123A and 164A! In every property ive been in storage heaters are fed from the same supply as the Consumer Unit but via a timeswitch thereby still using the one EP fuse 60A-100A.
Would the flats require 2 feeds or could this still be achieved with the 1 supply as the storage heating would not come on untill midnight?

 

[malcolmsanford]

To be honest I have yet to see an economy 7 installation and normal installation having separate supplies. 99% would be as you described either utilizing a time clock, or as now we have a dual meter, with the one 240/230 supply.

You may find that it would be 80-100amp rather than a 60amp which most flats would utilize quite easily. No I doubt very much you need 2 supplies unless there are other high load demands on the installation

 

[leestaf]

Thanks Malcolm

I was planning on using a 25mm SWA 100A supply with a dual E7 meter at the meter cupboard thereby using only a single supply, a timeclock at the CU controlling a contactor for the heaters.
Thanks