[anodyne33]

Having never seen the guts of one before I was surprised to see the difference in wire gauge between the high and low sides of the transformer. In my mind the only difference between the two sides was the number of turns. Huh.

[smcameron]

The latest Electroboom video is relevant: https://www.youtube.com/watch?v=LMT1sn1bKRY

[irrelative]

The low voltage side of a transformer needs to handle more current. You could use the same gauge on both sides and get the same voltage, but you'd experience more losses.

[kragen]

if you used the thin wire on both sides you'd get the same voltage but experience more losses

if you used the thick wire on both sides you'd get the same voltage but have a much heavier and more expensive transformer for an almost undetectable performance improvement