Main Breaker size Calculation (Feeding several VFD's)

[spaarky2002]

I have a system which is comprised of a main breaker feeding several smaller breakers, each circuit breaker feeds 1-5 VFD's, each VFD feeds one motor varying in size from 3-15HP. These VFD's do have a bypass circuit as well, and if I understand the code correctly this also makes a difference. I would like a clear understanding of the proper method to calculate the main breaker size. We are a UL panel shop, so if that changes anything please let me know. System is a 3PH/480VAC. Below is a spreadsheet which shows the VFD loads, and the percent of the individual breakers used each.

 

[petersonra]

UL508a tells you how to size the main CB.