What should spare or unused raceways be sealed with?

Spare or unused raceways should be sealed with sealants that are specifically identified for use with the cable insulation. This is important because using the correct type of sealant ensures compatibility with the materials used in the raceway and the cables that may be present. Sealants designed for this purpose help prevent the ingress of moisture, dust, and other contaminants, which can lead to corrosion or damage to the insulation and ultimately to the cables installed in those raceways.

This choice addresses safety and preservation of the electrical system's integrity. Additionally, the correct sealant can help to maintain the overall effectiveness of any firestopping or smoke control systems in place, ensuring that raceways do not compromise fire-rated barriers. Utilizing sealants that are specifically identified for use helps guarantee compliance with the NEC and manufacturer recommendations, promoting best practices in maintaining electrical installations.