voltage drop on multiple feeders

[Grouch1980]

Hey all,
another question!

When I follow the ASHRAE 90.1 2010 energy code, it mentions that feeders shall be sized for a voltage drop not exceeding 2%. Let's say you have the service switchboard, and feeder 'A' runs from the switchboard up to a distribution board on the 25th floor. Then feeder 'B' runs from this distribution board to a panel on the same floor. Then feeder 'C' runs from the panel to a sub-panel (same floor). The sub-panel then feeds branch circuits. The 2% voltage drop applies to the total of feeders 'A', 'B', and 'C'. How do you partition the 2% voltage drop between all three feeders? Or is it 2% per feeder? (which i doubt).

Thanks!

 

[GoldDigger]

It is total voltage drop before the start of the branch circuit, not including voltage drop to the service disconnect.
And how you apportion it is your problem, since the energy code is not a design document.

 

[Grouch1980]

It is total voltage drop before the start of the branch circuit, not including voltage drop to the service disconnect.
And how you apportion it is your problem, since the energy code is not a design document.

So it's voltage drop from the beginning of feeder A to the end of feeder C. I'm free to partition that 2% any way i choose amongst all three feeders?

 

[GoldDigger]

Yes.

 

[Grouch1980]

interesting. thanks!