maximum demand for property

[linnsound]

when ive assumed diversity for each circuit, and added them for maximum demand on property it totals 149A....Now the main cut out is BS 1361 rated at 100A....so how is this permissible...most domestic properties are protected by similar fuses with similar demand. What is the protocol. Am i right in thinking that this is halved? and if so then why?
thanks

 

[EdwardCurrent]

3 phase supply ?

Ed

 

[GaryMo]

How many circuits / what are they feeding?
Dow did you come to 149A?
Domestic, commercial, small industrial?

 

[linnsound]

domestic
ring up,13A
ring dwn, 13A (ie both rings at 40%)
ring kitchen, 32A(100%)
cooker & socket32A (15Kw - 1st 10A+30%remainder + 5A socket)
shower,40A
lights up
lights dwn,6A(66%)
immersion 13A

 

[GaryMo]

Your figures look spot-on, but, what's the likelihood of the upstairs and downstairs ringmains pulling 40% of 32A at the same time for a prolonged period?
What's the chances of the shower, cooker and immersion heater being on at the same time?
This is where sense has to come into it otherwise we would all require 150A supplies.

 

[linnsound]

yeah i agree Garymo, I was just unclear as to when it comes to certification and the maximum demand exceeds the main cut out what the protocol was. So is there a general rule of thumb, a further diversity even, to consider when assuming maximum demand for the property?

 

[GaryMo]

It's up to the individual.
If you have a loading of 149A after diversity and you have a general BS1361 IIB 100A incoming fuse then you can hardly put a figure of over 100A for MD.
I would generally put 100A for MD in that case but I never feel right doing it
I doubt the customer would appreciate you disconnecting his shower

 

[Adam_151]

Clamp meter time, or put down 80A (my fag packet estimate )

 

[FatGit]

How common are 3ph supplies in domestic settings? Are much more are the bills than a standard supply.