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Cable Calculations - Diversity Applied

Apostolos
Good morning everyone.

This is a theoritical question that I have however come across....really a lot when inserting my loads in Amtech!!!!!

I have a DB which feeds lighting and small power in a reception area in a hotel.

The DB has various lighting circuits and various small power circuits (sockets, door access controllers, heaters, automatic doors etc etc etc)

As I understand there is one type of diversity that is common sense and is the "concurrency factor" which is applied to the DB as a whole.

I am more interested however in additional diversities for the individual circuits.

My question is this.

I have a room where the lights are all on or all off through presence detection. I anticipate that within a typical day the lights will be on 6 hours. That is 25% of the day. Does this mean that I sould insert for this specific circuit an individual diversity factor of 0.25?

Do I interpret this correctly?
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    Well it depends if it is the same 6 hours on for all the lights. Generally I suspect not, but not fully staggered either -  I  suspect that nearly all the lights will be on at certain times of day say as folk are rushing around breakfast time... Certainly they will all be off at once - 3 AM probably?

    Then we are into the dark arts of how long each day can you run things at 200% load for without actually having a problem - usually in practice, longer than you think, but it would be 'brave' to design to that.

    Is this a real example ? Unless the area is massive,  one 16A 3 phase supply covers a lot of modern lights, and is normally set so you can isolate zones that are far from fully loaded, to ensure thta the effect of any one trip is not too serious. After all you do not want to shut down large chunks of the building after water gets into a single fitting from the room above. Having half a restaurant lit is far better than  no restaurant or kitchen... I assume you already use the true loading - so many hundred 25 watt LEDs or whatever, not the old 'assume 100W per lamp holder'.

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  • 0
    Well it depends if it is the same 6 hours on for all the lights. Generally I suspect not, but not fully staggered either -  I  suspect that nearly all the lights will be on at certain times of day say as folk are rushing around breakfast time... Certainly they will all be off at once - 3 AM probably?

    Then we are into the dark arts of how long each day can you run things at 200% load for without actually having a problem - usually in practice, longer than you think, but it would be 'brave' to design to that.

    Is this a real example ? Unless the area is massive,  one 16A 3 phase supply covers a lot of modern lights, and is normally set so you can isolate zones that are far from fully loaded, to ensure thta the effect of any one trip is not too serious. After all you do not want to shut down large chunks of the building after water gets into a single fitting from the room above. Having half a restaurant lit is far better than  no restaurant or kitchen... I assume you already use the true loading - so many hundred 25 watt LEDs or whatever, not the old 'assume 100W per lamp holder'.

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