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Hi all,

This is my first post on this forum. I'm currently doing my C&G 2365 and I've found myself completely stumped on a problem that's probably quite simple, but which I've had a lot of conflicting answers for from various people, which has left me a little confused.

I'm working on a design assignment and I'm calculating my maximum demand for a sub-board and distributing it across phases so that I can select a fuse and an armored cable to feed it from the main board. Two of my circuits on the sub-board are 3-phase.

Anyway, the thing that had me stumped was this. One of my three phase loads is described as "pool & sauna equipment that requires a 32A 400V 3-phase and neutral supply."

A classmate of mine has told me that this means 32A per phase, whereas someone I know in the industry has read it as meaning 32A across phases.

From what I understand, from a star-wound configuration IL=IP, so there is 32A in each phase and this does not change between lines (only voltage). So in my head, they're both correct. However, my classmate has tripled this value to add to his demand (a figure later to be divided into three phases) to a a big old 96A. Others that have chimed in have divided 32A into 3 to get 10.66A. I'm assuming that the rule IL=IP still applies even though the feed is technically not coming from a star-wound transformer, so wouldn't both these approaches be incorrect? Shouldn't we just be adding the 32A to max demand and be done with it?

I really appreciate any clarification I can get on this.

Happy Saturday!
 

buzzlightyear

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