Which type of coupling is used with flexible metal conduit (FMC)?

When working with flexible metal conduit (FMC), the coupling type specifically designed for this application is known as the FMC coupling. This type of coupling provides a secure connection between sections of FMC, allowing for flexibility and movement while maintaining protection against environmental factors. FMC couplings are designed to accommodate the unique properties of flexible metal conduit, which is intended to bend and follow the contours of a space while still offering electrical grounding and physical protection for wiring. Their design ensures that they can handle the movement and mechanical stress of installations where flexibility is required.

Other coupling types, while useful in different electrical applications, do not provide the same level of functionality and compatibility with FMC. Rigid couplings, for instance, are meant for use with rigid conduits, and a compression coupling typically connects rigid tubing but is not appropriate for flexible metal conduit. Split couplings can have their applications, but again, they do not serve the specialized needs of FMC installations in terms of ensuring secure, flexible connections that meet regulatory standards.