Panelboard placement based on voltage drop

[Defenestrator]

How do you guys place panelboards around a facility to ensure adequate coverage?

Are there any rules of thumb used to place panelboards? What do power factor do you use for voltage drop calcs, 0.85? What percentage of max load for a circuit would you use to calculate the voltage drop? 80% of the derated continuous load? do you always assume the smallest allowable conductor according to the ampacity tables in section 310.15 of the NEC?

Some people draw a circle with a certain radius with the panelboard centered on the equipment, but to me that seems kinda lazy because circuits don't travel in a straight line, they run orthogonal to the lines of the building. Others place a panelboard centrally for a certain amount of square footage, but im not sure where they get those numbers

my situation is that i need to place 120/208v and 277/480v panelboards but the circuits have to go up 25ft and then back down 25ft. Its new construction, not renovation, so i have some leeway with where i want to place the panelboards. The engineer I'm working with told me to draw a diamond, whose size is determined my the max circuit length based on vdrop, minus vertical offset

i know im overthinking this and there must be some easier way to do it. Any advice would be appreciated

 

[electrofelon]

Honestly, I hardly ever think about or calculate any voltage drops. Typically I lay out a building to have panel boards conveniently located for less branch circuit wiring and wire pulling and VD on the branch just isn't an issue 99.3% of the time.

 

[Fred B]

Unless you are dealing with numbers in the 100's+ realm for your circuit runs, voltage drop would be minimal. Most time VD can be accommodated by conductor size increases. Putting panel boards to convenient location to service connection or utilization points is my normal.
If runs are long what is gained by limiting circuit VD would need to be accommodated in the feeder runs. Most times cost of bumping a branch circuit wire size less than bumping a feeder size.