It is a foul if u don't hit the lowest numbered ball , and a rail after contact
But sometimes you can turn a foul into a positive
If u can't hit ur ball
Perhaps create an intentional cluster with the purpose of an intentional foul
Hoping to make a run out less likely
Here's a little something for the thread starter:
http://www.youtube.com/watch?v=Ja9y8Lv_A1s