Flexible metal conduit (FMC) is a versatile electrical conduit used to protect and route electrical wiring in various commercial and industrial applications. This article provides an in-depth examination of FMC, covering its construction, types, applications, compliance, and industry standards.
Construction of Flexible Metal Conduit
FMC is manufactured using a spiral wound strip of heavy gauge, corrosion-resistant, hot-dipped galvanized steel (Southwire, 2023). The core of the conduit is typically constructed with a square locked steel strip with an integral copper-bonding strip enclosed within the steel convolutions. A rugged, flame-retardant, flexible PVC jacket is extruded over the steel core to provide protection from liquids, oil, certain chemicals, temperature, extreme weather, and sunlight (Southwire, 2023).
Types of Flexible Metal Conduit
There are two primary types of FMC: standard FMC and liquidtight flexible metal conduit (LFMC) (NEMA, 2023). Standard FMC is designed for dry indoor locations and is often used for short runs between a wall box and a motor or fixed appliance. LFMC, on the other hand, has a plastic coating and, when used with sealed fittings, it becomes watertight. LFMC is commonly employed in outdoor equipment, such as air conditioner units (NEMA, 2023).
Applications of Flexible Metal Conduit
FMC is widely used in commercial and industrial buildings to protect electrical wiring. It is suitable for both indoor and outdoor installations and can be used in various environments, including areas with exposure to moisture, oil, and chemicals (Southwire, 2023). Some common applications of FMC include:
- Construction of commercial and industrial properties
- Dry indoor locations, often for short runs between a wall box and a motor or fixed appliance (e.g., garbage disposal)
- Outdoor equipment (e.g., air conditioner units)
Compliance and Standards for Flexible Metal Conduit
FMC complies with the National Electrical Code (NEC) and is tested and certified by Underwriters Laboratories (UL) (NEMA, 2023). It also meets the CSA Standard UL 360/CSA C22.2 No. 56-17 for Flexible Metal Conduit and Liquid-Tight Flexible Metal Conduit (NEMA, 2023).
Conclusion
Flexible metal conduit is a versatile and widely used electrical conduit that provides protection and routing for electrical wiring in various commercial and industrial applications. Its construction, types, applications, compliance, and industry standards are essential considerations for electrical professionals working with FMC.
References
- Southwire. (2023). Titan®2 Type HC Liquidtight Flexible Metal Conduit. Retrieved from https://www.southwire.com/wire-cable/flexible-conduit/titan-2-type-hc-liquidtight-flexible-metal-conduit/p/FC20
- NEMA. (2023). Flexible Metal Conduit. Retrieved from https://www.nema.org/membership/products/view/flexible-metal-conduit
FAQs
What is flexible metal conduit?
Flexible metal conduit (FMC) is a type of electrical conduit made from a spiral wound strip of galvanized steel, providing flexibility and protection for electrical wiring in various applications.
What are the different types of FMC?
There are two main types of FMC: standard FMC and liquidtight flexible metal conduit (LFMC). Standard FMC is designed for dry indoor locations, while LFMC has a plastic coating and is watertight when used with sealed fittings.
Where is FMC used?
FMC is commonly used in commercial and industrial buildings to protect electrical wiring in various environments, including areas with exposure to moisture, oil, and chemicals. It is suitable for both indoor and outdoor installations.
What are the advantages of using FMC?
FMC offers several advantages, including flexibility for easy routing, resistance to corrosion and chemicals, and protection of wiring from physical damage. It is also relatively easy to install and maintain.
What are the disadvantages of using FMC?
FMC can be more expensive than other types of conduit, and it is not suitable for high-temperature applications. Additionally, care must be taken during installation to avoid kinking or crushing the conduit, as this can compromise its integrity.
What are the safety considerations when using FMC?
Proper installation and maintenance of FMC are crucial for safety. Ensure that the conduit is securely fastened and properly grounded. Avoid overloading the conduit with too many wires, as this can lead to overheating and potential fire hazards.
What are the industry standards for FMC?
FMC must comply with the National Electrical Code (NEC) and be tested and certified by Underwriters Laboratories (UL). It should also meet the CSA Standard UL 360/CSA C22.2 No. 56-17 for Flexible Metal Conduit and Liquid-Tight Flexible Metal Conduit.
How do I choose the right FMC for my application?
Consider the environment where the FMC will be installed, the type of wiring it will protect, and the desired level of flexibility and protection. Standard FMC is suitable for dry indoor locations, while LFMC is ideal for outdoor or wet areas. Always consult with a qualified electrician to determine the appropriate FMC for your specific needs.