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Total Building Load in KVA

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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0 Former Community Member over 5 years ago

OMS:

As a quick sanity check, and using 240V, we know 1kw is 4A at 240V

Regards

OMS

Hi OMS, Has your account been hacked? 1 kW is 4A at 250 V?
0 Former Community Member over 5 years ago

weirdbeard:
OMS:

As a quick sanity check, and using 240V, we know 1kw is 4A at 240V

Regards

OMS

Hi OMS, Has your account been hacked? 1 kW is 4A at 250 V?

True - but we tend not to talk about the single phase voltage being 250, we usually say it's 240V when discussing single phase

Much the same as we tend to say "ohh, that's a 415Volt Dist Boad"

None are strictly correct, just that it's an Old Skool way, to rapidly sanity check something where the engineer is focusing on the third decimal place and perhaps not seeing the big picture

For the OP, it would be enough to suggest you need a 400A TP&N service, providing 300kVA - which may just suggest for a particular project, that more diversity may need to be applied - particularly in comparison to other similar facilities

Best Regards

OMS

Total Building Load in KVA

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