jar546
CBO
What it essentially means is that:
Heavy conductors and cables tend to stress the conductor insulation at raceway terminating points. Care must be taken at raceway and cable terminations to reduce the risk of insulation failure at conductor insulation stress points. This is often done by using insulating bushings or fittings with rounded edges; however, there are multiple options to achieve the desired protection of the insulation. The temperature ratings of the insulating bushing must coordinate with the insulation of the conductor to ensure that the conductor is protected for its entire life cycle.
Whether provided separately or as part of a fitting, listed insulating bushings are colored black or brown to indicate a temperature rating of 150°C and any other color to indicate a rating of 90°C unless specifically marked for a higher temperature. The use of a double locknut, with one on the inside and one on the outside of the enclosure with locknuts is necessary because the raceway cannot be secured by the fiber or plastic bushing.
Heavy conductors and cables tend to stress the conductor insulation at raceway terminating points. Care must be taken at raceway and cable terminations to reduce the risk of insulation failure at conductor insulation stress points. This is often done by using insulating bushings or fittings with rounded edges; however, there are multiple options to achieve the desired protection of the insulation. The temperature ratings of the insulating bushing must coordinate with the insulation of the conductor to ensure that the conductor is protected for its entire life cycle.
Whether provided separately or as part of a fitting, listed insulating bushings are colored black or brown to indicate a temperature rating of 150°C and any other color to indicate a rating of 90°C unless specifically marked for a higher temperature. The use of a double locknut, with one on the inside and one on the outside of the enclosure with locknuts is necessary because the raceway cannot be secured by the fiber or plastic bushing.