Actually when transformer is manufactured  winding
insulation have major role.That is the number of
turn,insulation strength
and many other factor does remain same in both
winding.dielectric strength mainly depend upon
voltage(p.d).As potential difference is increased
,electrostatic stress on insulator is increase and at
certain voltage insulation rapture.Dielectrc strength of
insulator used in high tension side is high compare to low
tension side.
 When low tension side of transformer is connected with high
voltage then there is chance of insulation failure.Because
dielectrc strength of low tension side is small as compare
to high tension side.
 Theoretically it is possible.