The way I read the sections you are citing, if a non metallic box has built in clamps, I fasten within 12" down the sheath, but, if the non metallic box does not have built in clamps (or some other cable clamping means), then I fasten within 8" down the sheath.
Al
[This message has been edited by ElectricAL (edited 07-23-2003).]
