All questions and answers are based on the 2014 NEC.
Q. Please explain the 10-ft tap rules?
A. Except as permitted by Sec. 240.21(A) through (H), overcurrent devices must be placed at the point where the branch circuit or feeder conductors receive their power. Taps and transformer secondary conductors aren’t permitted to supply another conductor (tapping a tap isn’t permitted) (see Fig. 1).