I have a 480V three-phase system that has 42 slots. There is an A/C unit connected to one of the slots available. The specifications of the A/C unit are the following.

Voltage: 460[v]/3[phase]/60[hz]

HP(Horse Power): 2.4

MCA(Minimum Circuit Amps): 30 [amps]

FLA(Full Load Amps): 2.6 [amps]

MOCP(Maximum Overcurrent Protection): 50 [amps]

Heat: 25 [kw]

As far as I understand, my boss has been using MCA as the operating current for the A/C unit, and he has been calculating the total current per phase using MCA. In order to find amperes on a three-phase system, I have been using the following fomula.

amperes = (kilowatts x 1000) / (volts x power-factor x 1.73) based on Ugly's Electrical References

Using the equation above, I have ameres = (25 x 100)/(480 x 1 x 1.73) = 30.106 [amps].

Question: Would it be safe to say that the amperes per phase is 30.106 [amps]? If so, would it also be safe to say that phase-B & phase-C have the exact amperes with different phase (radian or degree)?

Let's say that there are three more circuits with the same specifications of the A/C unit above on circuit number 1, 2, 3, and the one above is on 4. Would the total amperes per phase be 120 [amperes] per phase?

I have a client, Senior Electrical Engineer, who wants to divide the current by three. I am thinking that she considers a three-phase system as a parallel circuit with the same resistance. Do you think she is right, or we (my boss & I) are right?

This will cause a big problem because if our client is right, we may have oversized our wire size and breaker size (they are already installed on the rig). But, if we are right, then we need to tell our client that she is wrong. If we install wire and breaker based on her calculation, it will burn out the panel (worst-case-senario).

If I can prove whether she is right or wrong with proof, that would be a relief.

Thank you,

Jason