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Underground Conduit - Encase or Direct Burial? (NEC 300.5)

Question asked by kedwindominguez on May 22, 2017
Latest reply on May 22, 2017 by jhren1

Design scenario:

Conduit has to be installed from a pad mount transformer secondary to a electrical room (MCC).  In between has no traffic and is a industrial location.  



Applicable Code (NEC 2014)


According to 300.5 

(C) Underground Cables and Conductors Under Buildings.
Underground cable and conductors installed under a building
shall be in a raceway.


According to Table 300.5 Note 2

2. Raceways approved for burial only where concrete encased shall require concrete envelope not less than
50 mm (2 in.) thick.


My questions is:

  • If conduit is installed underground, is it safe to assume the conduit will always be concrete encased? if not, when would be the exception?



A colleague came up with the following response:


NEC 2014


Raceway An enclosed channel of metallic or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code.

 Enclosed Surrounded by a case, housing, fence, or wall(s) that prevents persons from accidentally contacting energized parts.

His interpretation is that conduits are not considered raceways therefore you can do direct burial, unless the client has site specific standards


Thank you for your assistance,


Kedwin Dominguez