The instructions that came with your fixture will tell you.
Which Wire Is Black/wire (both Are Clear)?
1.)The wire with writing down the entire length is the black.
2.) Or the wire with three raised ridges is not the black.
The reasoning behind this is because the code reads as follows:
The neutral wire or grounded conductor shall be either white, or have three lines marked down its entire length, or three raised lines down it entire length.
Green or bare is reserved for ground; Therefore all other conductors are reserved for ungrounded conductors( For example: Black)
2.) Or the wire with three raised ridges is not the black.
The reasoning behind this is because the code reads as follows:
The neutral wire or grounded conductor shall be either white, or have three lines marked down its entire length, or three raised lines down it entire length.
Green or bare is reserved for ground; Therefore all other conductors are reserved for ungrounded conductors( For example: Black)