Nonmetallic Conduit below/above ground

[steelbuster]

Schedule 40 below ground and Schedule 80 above (exterior) right? Where is that code reference? I'm looking at 347 and I don't really see a spec for rigid. This is for an overhead service entrance on a building.

 

[wbalsam1]

Re: Nonmetallic Conduit below/above ground

Hi: You can check out 347-1 and 347-17. Also look at 300-5(d)where the code indicates sch. 80 where subject to physical damage. The "subject to physical damage" term is to be judged by the AHJ. It's a little hard to imagine a sch. 40 nm conduit being subject to physical damage above the meter channel, but not below, where it might be subject to contact with autos, weed-eaters, etc.

[ August 15, 2005, 06:52 PM: Message edited by: wbalsam1 ]

 

[augie47]

Re: Nonmetallic Conduit below/above ground

Art 352 in the 2005 Code

The UL White Book("General Information for Electrical Equipment"), (DZYR) identifies Sch 40 Non-metallic for above ground use when not subject to physical damage. Sch 80 is suitable for use where exposed to physical damage.

 

[steelbuster]

Re: Nonmetallic Conduit below/above ground

Thanks...The physical damage phrase is the catch-all.

 

[redfish]

Re: Nonmetallic Conduit below/above ground

352.10 Uses Permitted
The use of RNC shall be permitted in accordance with 352.10(A) through (H).
FPN: Extreme cold may cause some nonmetallic conduits to become brittle and therefore more susceptible to damage from physical contact.
(A) Concealed RNC shall be permitted in walls, floors, and ceilings.
(B) Corrosive Influences RNC shall be permitted in locations subject to severe corrosive influences as covered in 300.6 and where subject to chemicals for which the materials are specifically approved.
(C) Cinders RNC shall be permitted in cinder fill.
(D) Wet Locations RNC shall be permitted in portions of dairies, laundries, canneries, or other wet locations and in locations where walls are frequently washed, the entire conduit system including boxes and fittings used therewith shall be installed and equipped so as to prevent water from entering the conduit. All supports, bolts, straps, screws, and so forth, shall be of corrosion-resistant materials or be protected against corrosion by approved corrosion-resistant materials.
(E) Dry and Damp Locations RNC shall be permitted for use in dry and damp locations not prohibited by 352.12.
(F) Exposed RNC shall be permitted for exposed work where not subject to physical damage if identified for such use.
(G) Underground Installations For underground installations, see 300.5 and 300.50.
FPN: Refer to Article 353 for High Density Polyethylene Conduit: Type HDPE.
(H) Support of Conduit Bodies Rigid nonmetallic conduit shall be permitted to support nonmetallic conduit bodies not larger than the largest trade size of an entering raceway. These conduit bodies shall not support luminaires (fixtures) or other equipment and shall not contain devices other than splicing devices as permitted by 110.14(B) and 314.16(C)(2)

Rigid Nonmetallic Schedule 40 and Schedule 80 PVC Conduit (DZYR)
Rigid nonmetallic Schedule 40 PVC conduit is suitable for underground use by direct burial or encasement in concrete. Unless marked ``Underground Use Only'' or equivalent wording, Schedule 40 conduit is also suitable for above ground use indoors or outdoors exposed to sunlight and weather where not subject to physical damage.
Schedule 80 conduit has a reduced cross-sectional area available for wiring space and is suitable for use wherever Schedule 40 conduit may be used. The marking ``Schedule 80'' identifies the conduit as suitable for use where exposed to physical damage and for installations on poles to comply with Section 352.10(F) and 352.12(C).

Hope this helps.