Was there a change in the NEC code concerning the wire color of # 8 THHN? In the past you would apply colored tape to black # 8 THHN. It is my understanding that we now are required to use #8 wires that are colored the full length, similar to #12 and #10 THHN.
Use of white or green tape on a black 8 AWG conductor is a common code violation. The rules for this have not been clhanged in intent, but the language for the 2011 NEC was revised a bit, but same intent.