When installing a flexible cable drop to a machine that requires frequent moving, can the cable be installed directly connected to the overhead busway plug-in device (i.e., busway switch) using appropriate tension take-up support devices without an attachment plug? Assume the machine is in an industrial facility that uses qualified persons to maintain the installation. The length of the cable drop from the busway plug-in device to the tension take-up device is 12 ft, and cable drop is supported at a distance of 8 ft.

  1. Yes, per the requirements of 400.7(A) and (B) — including the exception.
  2. No. The connection to the supply of power must be through an attachment plug.
  3. No. Flexible cable may not be used in this application.
  4. Yes, but only when permitted by written permission from the authority having jurisdiction.

Answer: A

Sections 400.7(A) and (B) outline the permitted uses of flexible cords and cables. An exception to 400.7(B) makes reference to "as permitted in 368.56." This section of the NEC outlines the requirements for the branches from busways. Furthermore, an exception to 368.56(B)(2) notes that for industrial installations with qualified personnel, it is permitted to install a flexible cable drop that is connected without an attachment plug, with no length limitation from the busway plug-in device to the tension take-up support, provided the cable is supported at intervals not exceeding 8 ft. Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.