Which material is NOT suitable for raceway installation?

The material identified as not suitable for raceway installation is plastic, specifically when referring to certain types of plastic materials that may not meet the durability or protective requirements outlined in the National Electrical Code (NEC). While some plastics, such as PVC, are widely accepted and used in raceway system installations due to their insulating properties and resistance to corrosion, other forms of plastic may not provide the necessary mechanical protection or may be susceptible to environmental degradation.

On the other hand, materials like steel, fiberglass, and PVC are authorized for raceway installations because they are recognized for their strength, durability, and ability to protect electrical conductors. Steel raceways offer excellent physical protection and grounding capabilities, fiberglass provides a lightweight alternative that is resistant to corrosion, and PVC is commonly used for its non-conductive and moisture-resistant qualities. Each of these materials adheres to the safety and performance standards established in the NEC, making them suitable choices for raceway systems.