Conduit

Rigid Conduit, Fittings, and Accessories – Frequently Asked Questions
25701 Science Park Drive
Cleveland, Ohio 44122
216-464-3400
1-800-3CARLON (322-7566)
www.carlon.com
I'm trying to deal with a Government spec that speaks in terms of thick wall and
thin wall PVC. Can you tell me what these terms mean as they relate to your
products?
We refer to Schedule 40 conduit as heavy wall EPC (electrical plastic conduit)
and our Schedule 80 conduit as Extra Heavy Wall EPC. There is no official
definition of thin wall vs. thick wall as it is relative. I'm sure there is more
information in the government spec, such as a reference to a NEMA spec or
perhaps a UL standard.
Is nonmetallic rigid schedule 80 conduit approved for use in a class 1 division 1
area?
501.4(A)(1)(a) Exception, either Schedule 40 or 80 PVC conduit can be used if
the conduit is encased in concrete a minimum of 2" thick (all the way a round)and
buried a minimum of 24". Threaded rigid conduit has to be used on both ends for
the last 24" of underground to emergence or point of connection to the
aboveground raceway.
This is the only acceptable way to use RNC in Class 1 Div 1 (with the exception
of gas stations, fuel storage and other fuel dispensing).
Article 347 of the 1999 NEC Handbook states that PVC conduit must be
"marked" for 90 degree C conductors. Your literature states that Plus 40 and 80
is "rated for use with 90 C conductors". Is your Plus 40 and 80 actually UL listed
for 90 degree C conductors? What is UL E35297, and does it relate to the use of
90 degree C conductors? This same question applies to type DB raceway. Is it
UL listed for 90 C cable?
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