Maximum demand calculation

That will be at least as good as any other back of envelope method. 

The OSG is conservative and over-estimates the supply need, by a lot in some cases.  I might raise your current per socket to a whole amp if there are less of them - thinking older places with a socket or 2 per room and a tangle of 4 way loads under the table.  As above I like to also consider room area based loading - with a few limits, so we do not add in the  full area of any barn-like sheds with nothing in them, or the area of the lawn because there is a mower socket serving that area!

I'd be interested how you might add in an instant electric shower or 2, The OSG sort of assumes these run non-stop, but in reality this  is not as likely to be long duration as say a few hours on the EV charger.  Similarly OSG says that diversity does not apply the  the water heating in one property, but given the no. of 1 room flats that van be supplied from a 100A fuse (record seems to be about  6..)  each with water and heating to consider, perhaps with multi-occupant households, it could be assumed if  there is more than one water heater, they will not be on together very often..

Mike.

That will be at least as good as any other back of envelope method. 

The OSG is conservative and over-estimates the supply need, by a lot in some cases.  I might raise your current per socket to a whole amp if there are less of them - thinking older places with a socket or 2 per room and a tangle of 4 way loads under the table.  As above I like to also consider room area based loading - with a few limits, so we do not add in the  full area of any barn-like sheds with nothing in them, or the area of the lawn because there is a mower socket serving that area!

I'd be interested how you might add in an instant electric shower or 2, The OSG sort of assumes these run non-stop, but in reality this  is not as likely to be long duration as say a few hours on the EV charger.  Similarly OSG says that diversity does not apply the  the water heating in one property, but given the no. of 1 room flats that van be supplied from a 100A fuse (record seems to be about  6..)  each with water and heating to consider, perhaps with multi-occupant households, it could be assumed if  there is more than one water heater, they will not be on together very often..

Mike.