ok i dont do a whole lot with hooking up transformers outside of control equipment so i am kinda stumped with this little job in our shop, we are getting an axle test stand to run for acouple of weeks and i am currently working on the hookup and we just happen to have a 225kva 240-480 transformer laying around our shop. leftover from the previous tennants i guess. anyway, in the 05 book, table 450.3(b) lists primary protection as 125% and secondary not required, or primary as 250% with 125% on the secondary, which is easy enough to figure out, what is making me scratch my head here is where is secondary required, i plan on having it to cya with the equipment but my boss is trying to save some money and im trying to do this right. thanks, Rob

Rob,
If you have been reading Article 450, that only covers the overcurrent protection for the transformer itself. The secondary conductors will require protection per 240.21(C).
Don

thanks, just what i needed to know

rob