Q. A contractor installed a 2,000A, 480V, 3-phase feeder in six separate raceways, consisting of a total of six 500kcmil XHHW insulated conductors per phase. Four of the raceways are 3-inch trade size EMT. The other two raceways are 3½-inch RMC. All conductors are exactly the same length, per paralleled phase, and feature the same insulation type and conductor material. In addition, all are terminated in the same manner and have the same cross-sectional area. The inspector has turned this installation down. What could possibility make this installation non-Code compliant?

  1. Nothing. This installation is Code compliant.
  2. The raceways are not the same. You must change all raceway sizes to either 3½-inch EMT or 3½-inch RMC.
  3. The raceways are not the same. You must change all raceways to either EMT or RMC of the proper trade size.
  4. The installation has an incorrect number of conductors paralleled. Change the number of conductors per phase from six to five.
Answer: C

Where run in separate raceways or cables, the raceways or cables shall have the same physical characteristics (i.e., same type conduit) [310.4]. In addition, the installation shall meet these five requirements:

  1. All conductors shall be exactly the same length per paralleled phase.
  2. All conductors shall have the same insulation type.
  3. All conductors shall be made of the same material.
  4. All conductors shall have the same cross-sectional area.
  5. All conductors shall be terminated in the same manner.

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.