My reference to rule 26-254 with regard to sub.(5)a and b is up to date and was to show what the reference was that the Bussman catalogue used. The text from the NEC 450.3 was almost the same as the Canadian code 25th edition 2012. The are saying that if the primary and secondary do not have thermal protection use 250% and if the primary and secondary do have thermal protection and the impedance of the transformer is 6 ohms or less use 125% of the FLA. There chart shows for the primary max fuse, use 250% and for secondary use 167% or 125% depending on the more or less 9 amp rule. My point is that for dry type less than 750v the 9 amp rule does not apply and their pecentages for protecton is wrong.
26-254 once dealt with all transformers and 26-256 dealt with wire size for transformers. Or, are you saying that the Bussman catalogue refers directly to 26-254(5)? Anyway, if you don't like their catalogue, throw it away.