transformer primary wire size

[sluis]

I am hooking up 75 kva transformer from buss duct, located 150 feet away, with # 3 wire and 125 amp fuse. there is no disconnect at transformer, since buss switch is lockable. secondary is 230 volt 3 phase, with disconnect and 200 amp fuses. Am I supposed to run 130 amp wire all the way from buss switch because i have 130 primary fuses, even though max load would be 100 amp/

 

[Smart $]

Primary fuses... which is it? 130A or 125A. 125A is a standard size. May make a difference because you can run wires with any ampacity greater than the next lower standard fuse rating (and calculated load). That's 125A if you use 130A fuses... but 110A if using 125A fuses. With the latter, that'd be #2 copper... provided you do not have to derate below 111A.