Talk:Kennen/@comment-3213627-20120218232524/@comment-2095407-20120219123455

There is no fixed duration. Ulti lasts as long as there is not hit bolts left (Number of Bolts: 6 / 10 / 15; max 3 per enemy champion) and there is new targets (enemy champions) to hit.

One can hold this ulti quite some time in convenient circumstances. That is really scary for the enemy to be in its range or to join teamfight while it is up.