I've noticed for a while that my iPad had a tingling sensation when I brushed my hand along the back of the casing. I found out today that it was because the charger is not grounded, and this was intended by design.
I'm curious though, how did we avoid electrocution even though there is no ground? Why do other chargers like Samsung's need a ground, given they are both handheld electronics with probably similar power ratings? Does that mean it's unwise to use an iPad while charging when wet, even if we avoid touching the lightning cable?