What is flexible conduit for?

Electrical conduit is a raceway or piping system that protects wires and cables from impact, moisture, and vapors. It is a path for either power or communication (low voltage) electrical wiring. It is usually tubular and made of metal (galvanized steel, stainless steel, aluminum) or non-metallic materials (plastics) and is either rigid or flexible. Special types of conduit are required for wet areas and hazardous areas.

Flexible metal conduit (FMC) is typically available in diameters between 3/8" and 3", but larger sizes can sometimes be found. It is made by coiling self-interlocked aluminum or steel strips, which forms a hollow tube that wires can be pulled through. FMC comes in a standard wall (sometimes called full wall) thickness or a reduced wall thickness. Most manufacturers also produce an extra-flexible FMC for tighter bend radiuses, but this is generally not UL approved.

Standard FMC is recommended in dry areas where it would be impractical to install EMT or other non-flexible conduit, yet where metallic strength to protect conductors is still required. Because of its flexibility, the FMC can help reduce vibrations from passing from motor to structure through the conduit.

Liquid-Tight Flexible Metal Conduit (LFMC) is FMC covered by a plastic waterproof coating. Its interior is similar to FMC, but it is suitable for wiring in wet or damp locations. It can also be buried in the ground or embedded in concrete. There are many types of LFMC on the market depending on the type of resistance needed, including extreme temperatures, oil resistant, anti-bacteria, flame resistant, and reinforced. It also comes in various jacket colors for easy identification. LFMC used for computer wires is usually blue.

It is important to note that Flexible Metal Conduit is NOT the same as metal clad (MC) cable or armored cable (AC). MC cable and armored cable include permanently integrated conductors in the flexible metal armor. However, flexible metal conduit is a raceway that the conductors are pulled through after installation.