Just want to double check how I'm doing this. Can anyone tell me if I am missing something or is this right? I'm finding the existing load on an 800 amp 480V service to a building to consider different expansion options.
convert all 120/208 & 277/480V loads to VA.
480 3phase 100 HP motor with RLA 90 amps:
480 x 90 x 1.732 = 74,822.4 VA
277v 400watt MH high bays at 1.75 amps each:
277 x 1.75 = 484.75 VA each
208 3 phase well RLA 24 amps
208 x 24 x 1.732 = 8646 VA
208 1 phase heater 3.75 Kw = 3,750 VA
misc. 115V loads total 65 amps
115 x 65 = 7475 VA
I guess the main thing I'm looking for some confirmation on is the treatment of the 3-phase loads. when going from RLA to VA I do V x A x 1.732 = VA. then all my 1-phase loads I just do V x A = VA.
To get total load on the service, then I add all my VA together and do VA / (480 x 1.732) or the same as VA / 480 / 1.732 as entered in to calculator.
Does changing all the different loads into VA this way and then dividing them by the service voltage and use the 3-phase fixed value (1.732) account for everything? Do I need to consider anything else for the loads that convert from 480 to 208 within the space?
I think it is this simple, but I just want to know, am I overlooking anything. Thanks y'all.
