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NEC Chapter 3 Wiring Methods & Materials
About Lesson

Raceways are enclosed channels that are used to protect and support electrical cables and conductors. They come in various types, each designed for specific applications and installation requirements. In this lesson, we will discuss the different types of raceways and their installation requirements.

  1. Rigid metal conduit (RMC): RMC is a thick-walled metal conduit that is used for high-impact applications and where additional protection is required. It is typically made of galvanized steel or stainless steel and is installed with threaded fittings. RMC is suitable for both indoor and outdoor applications and is resistant to moisture, chemicals, and physical damage.

  2. Electrical metallic tubing (EMT): EMT is a thin-walled metal conduit that is used for light-duty applications where flexibility is required. It is typically made of galvanized steel or aluminum and is installed with compression fittings. EMT is suitable for both indoor and outdoor applications and is resistant to moisture, chemicals, and physical damage.

  3. Intermediate metal conduit (IMC): IMC is a medium-weight metal conduit that is used for intermediate applications between RMC and EMT. It is typically made of galvanized steel and is installed with threaded fittings. IMC is suitable for both indoor and outdoor applications and is resistant to moisture, chemicals, and physical damage.

  4. Flexible metal conduit (FMC): FMC is a flexible metal conduit that is used for applications where flexibility is required. It is typically made of steel or aluminum and is installed with fittings designed for flexible conduit. FMC is suitable for both indoor and outdoor applications and is resistant to moisture, chemicals, and physical damage.

  5. Non-metallic conduit (PVC): PVC is a plastic conduit that is used for low-voltage applications where physical protection is required. It is typically installed with fittings designed for PVC conduit. PVC is suitable for both indoor and outdoor applications and is resistant to moisture, chemicals, and physical damage.

Installation requirements for raceways include:

  1. Bends: Raceways should be installed with bends where necessary to accommodate changes in direction. The NEC specifies minimum bend radiuses for each type of raceway.

  2. Supports: Raceways should be installed with adequate supports to prevent sagging or stress on the raceway or cables. The NEC specifies the minimum spacing and maximum weight of cables that can be supported by each type of raceway.

  3. Joints and couplings: Joints and couplings between raceway sections should be installed according to the manufacturer’s instructions and the NEC requirements.

  4. Bonding and grounding: Raceways should be bonded and grounded to prevent electrical hazards. The NEC specifies the requirements for bonding and grounding for each type of raceway.

  5. Environmental factors: Raceways should be selected and installed based on the specific environmental conditions in which they will be used.

In summary, the selection and installation of raceways requires consideration of several factors, including the type of raceway, the installation requirements, bending radius, support, joints and couplings, bonding and grounding, and environmental factors. By following the guidelines outlined in the NEC and considering these factors, electrical professionals can ensure that their work is safe, efficient, and compliant with industry standards.

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