Conditions making wiping over the khuffs invalid
•When taking a bath becomes obligatory.
•If any part of the feet is exposed.
•Taking the khuffs off; and taking one of them off is like taking them both off,
•The lapse of the time limit.
•Taking the khuffs of doesn’t invalidate the wudhu but one can’t wipe over the khuffs again if he puts them on unless he performs a new wudhu with washing the feet.