3 phase transformer bank impedance when 120V windings are paralleled

[Distribution Grid Don]

I hope when the transformers are wired for 120V output for wye banks the impedance doesn't change, if it does me and a lot of other people have been calculating wrong values for years

I agree! Same for me, though its only been recently that I have had to review a large number of arcflash studies, and when I was explaining to some junior engineers how a 208 bank is set up, I started to wonder...