The present disclosure relates to a fiber optic telecommunications cable
assembly including a main fiber optic cable and a tether cable that
branches from the main fiber optic cable at a breakout location. The
fiber optic telecommunications cable assembly also includes a breakout
block mounted to the main fiber optic cable at the breakout location, and
an over-mold that covers the breakout block and at least a portion of the
main fiber optic cable. The breakout block defines a straight-through
channel in which the main fiber optic cable is received and a breakout
channel that branches out from the straight-through channel. The breakout
block includes seams with overlap configurations that prevent the
over-mold from entering the breakout block through the seams. The
breakout block also includes barrier dams for preventing bonding material
from entering the breakout channel.