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Q: When I bend a Category cable, it turns white? Why does it do that and is it bad for the cable?

A: Depending on the color of the jacket, when you bend some cables, it turns the jacket white. This is not a defect, nor will it impact the physical or electrical performance of the cable. Plenum and riser rated cables typically have PVC jackets. The PVC material used includes color compounds and flame retardant materials. When you bend the cable, you displace the color molecules and expose the flame retardant material, which is white. The whitening is more pronounced in plenum rated cables because that jacket material has more flame retardant in it than the riser rated versions. If you were to bend a plenum rated cable and see little or no whitening of the jacket, you should verify that the cable has, in fact, passed UL-910 flammability test required for a plenum rating.

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