Article 352
Rigid Polyvinyl Chloride Conduit: Type PVC
Part I. General
- Scope. This article covers the use, installation, and construction specifications for rigid polyvinyl chloride conduit (PVC) and associated fittings.Informational Note: Refer to Article 353 for High Density Poly‐ ethylene Conduit: Type HDPE, and Article 355 for Reinforced Thermosetting Resin Conduit: Type RTRC.
- Definition.
Rigid Polyvinyl Chloride Conduit (PVC). A rigid nonmetallic raceway of circular cross section, with integral or associated couplings, connectors, and fittings for the installation of elec‐ trical conductors and cables.
352.6 Listing Requirements. PVC conduit, factory elbows, and associated fittings shall be listed.
Part II. Installation
352.10 Uses Permitted. The use of PVC conduit shall be permitted in accordance with 352.10(A) through (I).
Informational Note: Extreme cold may cause some nonmetallic conduits to become brittle and, therefore, more susceptible to damage from physical contact.
- Concealed. PVC conduit shall be permitted in walls, floors, and ceilings.
- Corrosive Influences. PVC conduit shall be permitted in locations subject to severe corrosive influences as covered in300.6 and where subject to chemicals for which the materials are specifically approved.
- Cinders. PVC conduit shall be permitted in cinder fill.
- Wet Locations. PVC conduit 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.
- Dry and Damp Locations. PVC conduit shall be permitted for use in dry and damp locations not prohibited by 352.12.
- Exposed. PVC conduit shall be permitted for exposed work. PVC conduit used exposed in areas of physical damage shall be identified for the use.Informational Note: PVC Conduit, Type Schedule 80, is identi‐ fied for areas of physical damage.
- Underground Installations. For underground installa‐ tions, PVC shall be permitted for direct burial and under‐ ground encased in concrete. See 300.5 and 300.50.
- Support of Conduit Bodies. PVC conduit shall be permit‐ ted to support nonmetallic conduit bodies not larger than thelargest trade size of an entering raceway. These conduit bodies shall not support luminaires or other equipment and shall not contain devices other than splicing devices as permitted by 110.14(B) and 314.16(C)(2).
- Insulation Temperature Limitations. Conductors or cables rated at a temperature higher than the listed temperature rating of PVC conduit shall be permitted to be installed in PVC conduit, provided the conductors or cables are not operated at a temperature higher than the listed temperature rating of the PVC conduit.
352.12 Uses Not Permitted. PVC conduit shall not be used under the conditions specified in 352.12(A) through (E).
- Hazardous (Classified) Locations. In any hazardous (clas‐ sified) location, except as permitted by other articles of this Code.
- Support of Luminaires. For the support of luminaires or other equipment not described in 352.10(H).
- Physical Damage. Where subject to physical damage unless identified for such use.
- Ambient Temperatures. Where subject to ambient temperatures in excess of 50°C (122°F) unless listed otherwise.
- Theaters and Similar Locations. In theaters and similar locations, except as provided in 518.4 and 520.5.
352.20 Size.
- Minimum. PVC conduit smaller than metric designator 16 (trade size 1∕2) shall not be used.
- Maximum. PVC conduit larger than metric designator 155 (trade size 6) shall not be used.
Informational Note: The trade sizes and metric designators are for identification purposes only and do not relate to actual dimensions. See 300.1(C).
352.22 Number of Conductors. The number of conductors shall not exceed that permitted by the percentage fill specified in Table 1, Chapter 9.
Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.
352.24 Bends — How Made. Bends shall be so made that the conduit will not be damaged and the internal diameter of the conduit will not be effectively reduced. Field bends shall be made only with identified bending equipment. The radius of the curve to the centerline of such bends shall not be less than shown in Table 2, Chapter 9.
352.26 Bends — Number in One Run. There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes.
352.28 Trimming. All cut ends shall be trimmed inside and outside to remove rough edges.
352.30 Securing and Supporting. PVC conduit shall be instal‐ led as a complete system as provided in 300.18 and shall be fastened so that movement from thermal expansion or contrac‐ tion is permitted. PVC conduit shall be securely fastened and supported in accordance with 352.30(A) and (B).
ARTICLE 352 — RIGID POLYVINYL CHLORIDE CONDUIT: TYPE PVC 352.100
- Securely Fastened. PVC conduit shall be securely fastened within 900 mm (3 ft) of each outlet box, junction box, device box, conduit body, or other conduit termination. Conduit listed for securing at other than 900 mm (3 ft) shall be permit‐ ted to be installed in accordance with the listing.
- Supports. PVC conduit shall be supported as required in Table 352.30. Conduit listed for support at spacings other than as shown in Table 352.30 shall be permitted to be installed in accordance with the listing. Horizontal runs of PVC conduit supported by openings through framing members at intervals not exceeding those in Table 352.30 and securely fastened within 900 mm (3 ft) of termination points shall be permitted.
352.44 Expansion Fittings. Expansion fittings for PVC conduit shall be provided to compensate for thermal expan‐ sion and contraction where the length change, in accordance with Table 352.44, is expected to be 6 mm (1∕4 in.) or greater in a straight run between securely mounted items such as boxes, cabinets, elbows, or other conduit terminations.
Table 352.30 Support of Rigid Polyvinyl Chloride Conduit (PVC)
352.46 Bushings. Where a conduit enters a box, fitting, or other enclosure, a bushing or adapter shall be provided to protect the wire from abrasion unless the box, fitting, or enclo‐ sure design provides equivalent protection.
Informational Note: See 300.4(G) for the protection of conduc‐ tors 4 AWG and larger at bushings.
352.48 Joints. All joints between lengths of conduit, and between conduit and couplings, fittings, and boxes, shall be made by an approved method.
352.56 Splices and Taps. Splices and taps shall be made in accordance with 300.15.
352.60 Grounding. Where equipment grounding is required, a separate equipment grounding conductor shall be installed in the conduit.
Exception No. 1: As permitted in 250.134(B), Exception No. 2, for dc circuits and 250.134(B), Exception No. 1, for separately run equip‐ ment grounding conductors.
Exception No. 2: Where the grounded conductor is used to ground equipment as permitted in 250.142.
Part III. Construction Specifications
| Metric Designator | Trade Size | mm or m | ft | |
| 16–27 | 1∕2–1 | 900 mm | 3 | |
| 35–53 | 11∕4–2 | 1.5 m | 5 | |
| 63–78 | 21∕2–3 | 1.8 m | 6 | |
| 91–129 | 31∕2–5 | 2.1 m | 7 | |
| 155 | 6 | 2.5 m | 8 |
Conduit Size
Maximum Spacing Between Supports
352.100 Construction. PVC conduit shall be made of rigid (nonplasticized) polyvinyl chloride (PVC). PVC conduit and fittings shall be composed of suitable nonmetallic material that is resistant to moisture and chemical atmospheres. For use aboveground, it shall also be flame retardant, resistant to impact and crushing, resistant to distortion from heat under conditions likely to be encountered in service, and resistant to low temperature and sunlight effects. For use underground, the material shall be acceptably resistant to moisture and corro‐
Table 352.44 Expansion Characteristics of PVC Rigid Nonmetallic Conduit Coefficient of Thermal Expansion = 6.084 × 10–5 mm/mm/°C (3.38 × 10–5 in./in./°F)
Temperature Change (°C) | Length Change of PVC Conduit (mm/m) | Temperature Change (°F) | Length Change of PVC Conduit (in./100 ft) | Temperature Change (°F) | Length Change of PVC Conduit (in./100 ft) | |
| 5 | 0.30 | 5 | 0.20 | 105 | 4.26 | |
| 10 | 0.61 | 10 | 0.41 | 110 | 4.46 | |
| 15 | 0.91 | 15 | 0.61 | 115 | 4.66 | |
| 20 | 1.22 | 20 | 0.81 | 120 | 4.87 | |
| 25 | 1.52 | 25 | 1.01 | 125 | 5.07 | |
| 30 | 1.83 | 30 | 1.22 | 130 | 5.27 | |
| 35 | 2.13 | 35 | 1.42 | 135 | 5.48 | |
| 40 | 2.43 | 40 | 1.62 | 140 | 5.68 | |
| 45 | 2.74 | 45 | 1.83 | 145 | 5.88 | |
| 50 | 3.04 | 50 | 2.03 | 150 | 6.08 | |
| 55 | 3.35 | 55 | 2.23 | 155 | 6.29 | |
| 60 | 3.65 | 60 | 2.43 | 160 | 6.49 | |
| 65 | 3.95 | 65 | 2.64 | 165 | 6.69 | |
| 70 | 4.26 | 70 | 2.84 | 170 | 6.90 | |
| 75 | 4.56 | 75 | 3.04 | 175 | 7.10 | |
| 80 | 4.87 | 80 | 3.24 | 180 | 7.30 | |
| 85 | 5.17 | 85 | 3.45 | 185 | 7.50 | |
| 90 | 5.48 | 90 | 3.65 | 190 | 7.71 | |
| 95 | 5.78 | 95 | 3.85 | 195 | 7.91 | |
| 100 | 6.08 | 100 | 4.06 | 200 | 8.11 |
352.120 ARTICLE 353 — HIGH DENSITY POLYETHYLENE CONDUIT: TYPE HDPE CONDUIT
sive agents and shall be of sufficient strength to withstand abuse, such as by impact and crushing, in handling and during installation. Where intended for direct burial, without encase‐ ment in concrete, the material shall also be capable of with‐ standing continued loading that is likely to be encountered after installation.
352.120 Marking. Each length of PVC conduit shall be clearly and durably marked at least every 3 m (10 ft) as required in the first sentence of 110.21(A). The type of material shall also be included in the marking unless it is visually identifiable. For conduit recognized for use aboveground, these markings shall be permanent. For conduit limited to underground use only, these markings shall be sufficiently durable to remain legible until the material is installed. Conduit shall be permitted to be surface marked to indicate special characteristics of the mate‐ rial.
Informational Note: Examples of these markings include but are not limited to “limited smoke” and “sunlight resistant.”