Article 386 of the National Electrical Code (NEC) 2023 addresses the requirements for surface metal raceways. Surface metal raceways are electrical enclosures used to protect and contain conductors on the surface of walls, ceilings, and other structures. These raceways can be used in commercial, industrial, and residential applications, and provide a convenient solution for installing electrical wiring without the need for embedded conduits or access to interior walls.
The NEC defines surface metal raceways as enclosures that are designed to be mounted directly on surfaces, and that are made of metal with a length of 6 feet or less. These raceways are typically installed in areas where the installation of conduit is not feasible, such as on concrete walls or ceilings. They can also be used in areas where aesthetics are important, as they can be painted to match the surrounding surface.
Article 386 sets out the requirements for surface metal raceways, including their installation, size, and materials. One of the key requirements is that surface metal raceways must be securely fastened to the surface on which they are installed, and must be designed to withstand the weight of the conductors they contain. The NEC also requires that the raceway be properly supported and secured to prevent it from moving or becoming dislodged, which could cause damage to the conductors inside.
The size of surface metal raceways is also regulated by the NEC. The minimum size of a raceway is determined by the size of the conductors that it contains. The NEC provides guidelines for the maximum number of conductors that can be installed in a given size of raceway, which helps to ensure that the raceway does not become overcrowded and that the conductors are not subject to excessive heat or electromagnetic interference.
The materials used to manufacture surface metal raceways are also regulated by the NEC. The code specifies that raceways must be made of metal, such as steel or aluminum, and that they must be free of sharp edges or burrs that could damage the conductors. The use of plastic or other non-metallic materials for surface metal raceways is not allowed under the NEC.
Article 386 also sets out the requirements for bends and changes in direction in surface metal raceways. The code specifies the maximum angle of bend allowed, which is typically 90 degrees. Any changes in direction greater than 90 degrees must be made using fittings designed for that purpose. The use of conduit bodies or other devices to change direction in a surface metal raceway is not allowed under the NEC.
Finally, Article 386 addresses the requirements for grounding and bonding of surface metal raceways. The NEC requires that all surface metal raceways be properly grounded to prevent the buildup of static electricity and to protect against electrical shocks. The raceway must also be bonded to any adjacent metal surfaces, such as pipes or ductwork, to prevent the buildup of electrical potential between them.
In summary, Article 386 of the NEC 2023 provides guidance on the installation, size, materials, bends, and grounding of surface metal raceways. By following these requirements, electrical contractors and installers can ensure that their installations are safe, secure, and comply with the latest electrical safety standards.