Diversity factor for calculating loads ???

[1capybara]

I am a Yank electrician, I cant find where in 16th or 17th edition you have the
diversity factor for calculating loads.
Example:
1. In one office or sleeping room I put 4 power sockets on a 32 amp ring circuit.
We have 100 identical sleeping rooms or offices. What is the total load
that we calculate to figure out feeder size to the panel?
...
This is just an example, Im looking for where in BS7671 to find the answer?

 

[Guest123]

Do you have a copy of the On Site Guide to hand???

Basic diversity allowances are shown in there.

 

[Elidor]

Appendix 1 of the On Site Guide, more specificaly table 1B (Page 97) should show have your looking for.

 

[1capybara]

thanks, now I got it.:smart:

 

[ackbarthestar]

I am a Yank electrician, I cant find where in 16th or 17th edition you have the
diversity factor for calculating loads.
Example:
1. In one office or sleeping room I put 4 power sockets on a 32 amp ring circuit.
We have 100 identical sleeping rooms or offices. What is the total load
that we calculate to figure out feeder size to the panel?
...
This is just an example, Im looking for where in BS7671 to find the answer?

Unfortunately, the OSG and BS7671 will not be that much help in deciding the maximum demand in a real life situation.
100*32 = 3200A = complete nonsense!
or 32 + (99*16) = As above

You will need to look at the average demand for the whole lot or in groups.
PCs, lighting, telecomms et al
If there are no electric heating appliances then the overheads will drop considerably

CIBSE publish utilization tables relating expected electrical utilization with size of unit

 

[1capybara]

Ackbarthestar -
You said "CIBSE publish utilization tables relating expected electrical utilization with size of unit "
do you have a link to that?
But check out the attachment from Article 220 from NEC 2008.
See how easy it is to calculate Demand Factor in the states!!!

 

[malcolmsanford]

View attachment Guidelines_network_design.pdf

Here is a guide that the UK electrical supply industry use which takes in account area sizes

 

[ackbarthestar]

Ackbarthestar -
You said "CIBSE publish utilization tables relating expected electrical utilization with size of unit "
do you have a link to that?
But check out the attachment from Article 220 from NEC 2008.
See how easy it is to calculate Demand Factor in the states!!!

That particular article doesn't appear to be that helpful, no wonder you are looking for advice.

Try this article : http://www.liv.ac.uk/safety/safety_issues/electricity1/electricity_in_buildings_cibse_code_K.pdf

not bang up to date but will give you an idea of British Building services electrical design

 

[ackbarthestar]

View attachment 8555

Here is a guide that the UK electrical supply industry use which takes in account area sizes

A better example
That's simple enough times by 10.78 and you're in m^2