Delete comment from: Ken Shirriff's blog
On the ipod/ipad charger, I don't think the metal post is for grounding. The original version of the charger had the post made of plastic and it kept snapping off. Apple eventually changed to a metal post.
Joe
Oct 19, 2013, 12:49:01 PM
Posted to A dozen USB chargers in the lab: Apple is very good, but not quite the best