Lengths of flexible metal conduit longer than ___ feet are not acceptable as an equipment grounding conductor.

Flexible metal conduit (FMC) is used for electrical wiring in various applications due to its flexibility and ease of installation. However, when it comes to its use as an equipment grounding conductor, there are specific limitations to ensure safety and reliability. The National Electrical Code (NEC) specifies that FMC should not exceed a certain length to be effective as an equipment grounding conductor.

When FMC lengths exceed 6 feet, the resistance can increase, potentially compromising its effectiveness as a ground. This is due to the inherent nature of flexible conduits, which may introduce higher resistive properties over longer distances. Therefore, when the length of FMC exceeds six feet, it may not provide a sufficient path for ground fault current, which is crucial for the protection of equipment and personnel.

Hence, FMC longer than six feet is not recognized as an acceptable equipment grounding conductor because it may not fulfill the necessary safety and operational requirements in electrical installations. This clarification is essential for ensuring compliance with the NEC and enhancing safety in electrical systems.