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Monday, March 27, 2017
Question:
Charlie,
Could you give me some examples of permissible and non-permissible applications for Triplex or Quadruplex XLPE cables and any other information with respects to if it is or is not listed and compliance with 310.10?
For example, would it be acceptable for use in a temporary wiring application used outside, underground, for direct burial for 480 V three phase feeders?
Thanks for providing the service,
Derrick Atkins
A
Answer:
Hey Derrick thanks for your question and you are welcome. Section 310.10 has rules for conductors and specific provisions for insulated conductors such as those in wet locations or exposed to direct sunlight. Insulated conductors must also comply with Table 310.104 as stated in 310.104 but are not specifically required to be listed. As defined in Article an insulated conductor (Conductor, Insulated) is "encased within material of composition and thickness that is recognized by this Code as electrical insulation". Notice that XLPE is not one of the Types included in Table 310.104.
A new insulated conductor definition has been added to 396.2 in the 2017 NEC that includes overhead service conductors encased in a polymeric material with an Informational Note. As defined in Article 100 service conductors, overhead are on the "load side" of the service point so are owned by the customer. With this additional definition triplex and quadraplex cables are now specifically allowed but only for overhead service conductors, not feeders.