Which method is NOT acceptable for identifying different systems in combination surface metallic raceways?

The method that is not acceptable for identifying different systems in combination surface metallic raceways is textured finishes. Textured finishes may be aesthetically pleasing or beneficial for grip but do not provide clear, consistent, and easily understood identification of different raceway systems. Identification methods such as color coding, labeling, and tagging are widely accepted practices because they enhance visibility and understanding concerning which systems are being referenced, thus minimizing the risk of confusion during installation, maintenance, or troubleshooting. They offer a standardized approach that can be identified and understood quickly, which is essential for safety and effectiveness in electrical systems. Therefore, textured finishes do not fulfill the criteria for clear identification like the other methods do.