diversity of main supply for distribution board

[tongunn1]

i need to wire in a 200a distribution board from a 400a board in an ind factory. Do i take diversity into account. The on-site guide says no but the Bs 7671 says yes but doesnt state if its for distribution boards or single circuits

 

[malcolmsanford]

Yes industrial diversity is quite a complex design problem. You really do need to take into account what kind of work and loads will be expected on the installation.

If there are a motors in the installation the OSG do give you some diversity values in table 1B. 100% for the largest and then 75% for the next and so on for the remaninder.

Then if you have a lot of fixed loads then there is virtually no diversity you can use. But remember there will be loads you can off set these with ring finals, offices, store areas etc etc.

I always use a rule of thumb for industrial of adding up the protection devices and times by 0.8. Add up each phases PD and do that and whatever is the largest phase load that is your man.

 

[tongunn1]

I thought you can only use diversity for seperate circuits i.e feeding 3 off cookers etc. At the bottom of the page of the osg in the diversity section under the table, it says diversity can not be used for a supply to a distribution board, the supply cable must take the total load