2011 NEC
314.28(E) Power Distribution Blocks. Power distribution blocks
shall be permitted in pull and junction boxes over 1650 cm3
(1) Installation. Power distribution blocks installed in
boxes shall be listed.
(2) Size. In addition to the overall size requirement in the
first sentence of 314.28(A)(2), the power distribution block
shall be installed in a box with dimensions not smaller than
specified in the installation instructions of the power distribution
block.
(3) Wire Bending Space. Wire bending space at the terminals
of power distribution blocks shall comply with
312.6.