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Total Building Load in KVA

Michael Brennan
Hi All,


I have been asked to provide the total electrical load of a building.  The max load per phase is 426.3A, on a 3-phase supply.  The majority of this is made up of 1-phase (230V) loads, with a few 3-phase loads mixed in there.  I have designed the electrical distribution such that the loads are split as equally as possible, but I have a question on how to calculate the total KVA value for this supply.  I'm getting a little confused with the information provided online and thought I would check this with a reliable source (you guys!).  Can someone confirm which of the following is the correct calculation, please?


1) I = 426.3A (per phase).  V = 400V (per phase).  Therefore: (426.3 * 400 * 1.732) / 1000 = (426.3 * 692.8) / 1000 = 295.34KVA


2) I = 426.3A (per phase).  V = 230V (per phase).  Therefore: (426.3 * 230 * 1.732) / 1000 = (426.3 * 398.36) / 1000 = 169.82KVA


Many thanks in advance,


MJB
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    Thank you Broadgage, I really appreciate your comments.  The loads I have considered are total current of the socket circuits (20A radials mostly), and everything else I have looked at installed equipment data and taken the FLC's of the actual equipment (plus a little more for tolerance) as you mention above.  Your comment about the kitchen sockets is very appreciated, I will make sure to take this into consideration.


    Ultimately, the building has many different uses as the spaces are diverse within it, and as such it is hard to define the exact times of use etc.  I.e. offices, meeting rooms, commercial kitchen & cafe, auditorium, dance studio, etc.


    Many thanks for your comments though, I appreciate everyone on these forums who is able to offer support!!
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  • 0
    Thank you Broadgage, I really appreciate your comments.  The loads I have considered are total current of the socket circuits (20A radials mostly), and everything else I have looked at installed equipment data and taken the FLC's of the actual equipment (plus a little more for tolerance) as you mention above.  Your comment about the kitchen sockets is very appreciated, I will make sure to take this into consideration.


    Ultimately, the building has many different uses as the spaces are diverse within it, and as such it is hard to define the exact times of use etc.  I.e. offices, meeting rooms, commercial kitchen & cafe, auditorium, dance studio, etc.


    Many thanks for your comments though, I appreciate everyone on these forums who is able to offer support!!
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