Classes A, B, C, D, G, and M. 1  Classes A â C permit operation of motor vehicles based on GVW rating and must be renewed every 5 years. 2  Classes D and G are valid for operation of a single motor vehicle with a GVW rating of 26,000 lbs. or less.
Electrical Metallic Tubing (EMT) Electrical metallic tubing (EMT), also commonly called thin-wall, is a listed steel raceway of circular cross section, which is unthreaded, and nominally 10â² long. 20â² lengths are also available. Covered by Article 358 of the NEC, EMT is available in trade sizes 1/2 through 4.
Chapter 14. Duct and Conduit. Introduction. The general purpose of conduit, or duct, is to provide a clear, protected pathway for a cable, or for smaller conduits, sometimes. called innerducts. Advances in cable technologies, as well as the. expense of repairing sensitive cable materials like fiber optic.