Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.
In general a tap conductor is a conductor where the line side overcurrent protective device exceeds the ampacity of the conductor. However there are other sections of the NEC that do permit oversized overcurrent protective devices to be used on conductors that are not tap conductors. The most common example is a motor circuit conductor.