Feeder Tap Rules
10-Foot Feeder Tap Rule [240.21(B)(1)]
Feeder tap conductors can be run not over 10 ft without overcurrent protection at the point they receive their supply, but they must be installed in accordance with the following requirements: Figure 1
(1) The ampacity of the tap conductor is:
1 Not less than the computed load in accordance with Article 220, and
2 Not less than the rating of the device supplied by the tap conductors or the overcurrent protective device at the termination of the tap conductors.
(2) The tap conductors do not extend beyond the equipment they supply.
(3) The tap conductors are installed in a raceway if they leave the enclosure.
(4) The tap conductors have an ampacity of no less than 10 percent of the ampacity of the overcurrent protection device from which the conductors are tapped.

25-Foot Feeder Tap Rule [240.21(B)(2)
Feeder tap conductors can be run not over 25 ft without overcurrent protection at the point they receive their supply, but they must be installed in accordance with the following requirements: Figure 2
(1) The ampacity of the tap conductors is not less than 1/3 the ampacity of the overcurrent protection device protecting the feeder.
(2) The tap conductors terminate in a single circuit breaker, or set of fuses having a rating no greater than the conductor ampacity as listed in Table 310.16.
(3) The tap conductors are suitably protected from physical damage or are enclosed in a raceway.