Voltage determining factor for Table 110.34 A

[indy1808]

What determines the correct voltage when using table 110.34 (A)???
for example I have a 15kv switchboard being installed in a 13.8 Y/ 8 kv distribution system.

I must chose between 15,13.8 or 8kv.
So, if I use the secondary is (8KV) which would reference Table 110.34 A, col. 2 and condition 2?

If so what determined that the 8KV was used?
Please repy with a reference. Thank You in advance.

 

[LarryFine]

You always use the higher (line-to-line) voltage when discussing voltage class, so 13.8kv.