Q. A cable tray system has been installed to support service entrance conductors. The service entrance conductors consist of six sets of three-conductor 500kcmil interlocked armored cables installed in parallel in a single layer in the tray. An additional feeder, consisting of three sets of parallel three-conductor 500kcmil interlocked armored cables, has been installed in a single layer in the same cable tray. The cable tray is wide open (i.e., no barriers or dividers). Is this installation NEC compliant?

  1. Yes, because all cables are interlocked armored cables.
  2. No, because conductors other than service entrance conductors are not permitted in the same cable tray with service entrance conductors, unless a solid fixed barrier of a material compatible with the cable tray is installed to separate the service entrance conductors from the other conductors.
  3. No, because interlocked armored cables are not permitted to be used as service entrance conductors.
  4. No, because cable trays cannot be used to support service entrance conductors.

Answer: B

In general, you’re permitted to use cable trays to support service entrance conductors as long as other conductors are not placed in the same tray. The only time you’re permitted to place other conductors in a cable tray with service entrance conductors is if you equip the cable tray with a fixed barrier of a material compatible with the cable tray and physically separate the service entrance conductors from the other conductors. [230.44]

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.