Please excuse me for my newbe question, but I have not spent much time looking into the actuall enforcement of penalties untill just now. I am not finding anything that tells you when you apply half the distance to the goal. I am going to assume that it is once you can no longer apply the full yardage of a penalty? i.e. Illegal personal contact (0n B) at B's 10 yardline. at this point it would have to be placed at the 5? Thanks!

In NFHS, you enforce half the distance anytime the full penalty would be more than half the distance to the goalline from the point of enforcement -- in other words, inside the 30 on a 15 yard penalty, inside the 20 on a 10-yard penalty, and inside the 10 on a 5-yard penalty.

So to make sure I get this correct. at Illegal Personal contact at B's 8 yard line would then bring the ball to the 4 yrd. line or the same penalty at B's 25 would bring it to the 12 yrd line?

Assuming those are were you enforce the penalty from then yes. 12.5 yard line on the second one to be exact.

NFHS Rule 10-1-5
 

Enforcement of acannot take the ball more than 1/2 the distance to the goal line.

Let's try it again
 

Enforcement of a penalty...

Canadian Philosophy
 

The Canadian equivalent is 8.3.