Where is communication flat cable (CFC) permitted to be used?

Communication flat cable (CFC) is designed with specific installations in mind to ensure safety and functionality. Its use under carpet squares is permitted because it allows for flexible installation in a variety of indoor environments while minimizing exposure to potential damage. This location provides protection from physical contact and maintains the integrity of the cable, as CFC is typically low-voltage and intended for use where it is less likely to be disturbed.

In contrast, using CFC inside walls may pose risks concerning accessibility and potential damage to the cable from structural movements or renovations. Applications above ceiling tiles can expose the cable to environmental conditions that could affect its performance and safety, especially in areas where moisture or dust could accumulate. Outdoor applications are generally not suitable for CFC as it is not designed to withstand weather elements, which can lead to degradation and eventual failure of the cable.

Thus, the correct context where CFC is permitted is under carpet squares, where it is protected and serves its intended communication function effectively.