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PVC Conduit (Schedule 40 and 80)

Rigid PVC conduit comes in Schedule 40 and the thicker-wall Schedule 80. Schedule 80 is the type used where the conduit is exposed to physical damage, and long runs need expansion fittings.

Ref EL-0022NEC 352UL 651NEMA TC 2NEMA TC 3

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

Rigid polyvinyl chloride conduit (PVC) is a nonmetallic raceway covered by NEC Article 352. It is listed to UL 651 and made to NEMA TC 2. Fittings are made to NEMA TC 3. Schedule 40 has a standard wall. Schedule 80 has the same outside diameter with a thicker wall, so the inside diameter is smaller. PVC is light, does not rust and is joined with solvent cement.

How to identify

Electrical PVC is usually gray and printed along its length with "Schedule 40" or "Schedule 80", trade size, sunlight resistance where marked, and the UL listing. Plumbing pipe is usually white and is not listed as electrical conduit. Belled ends on one end of each length are common.

Schedule 40 vs Schedule 80

Feature	Schedule 40	Schedule 80
Wall	Standard	Thicker
Outside diameter	Same as Schedule 80	Same as Schedule 40
Inside diameter	Larger	Smaller
Conductor fill	Use Schedule 40 row in Chapter 9	Use Schedule 80 row, less fill
Physical damage locations	Not for locations subject to damage	Identified for physical damage
Fittings	Same fittings fit both	Same fittings fit both

Expansion fittings

PVC grows and shrinks much more than metal with temperature. NEC 352.44 calls for expansion fittings where the expected length change is 6 mm (1/4 in) or more in a straight run between secured points. Table 352.44 gives the change in length for each temperature range. Common places are rooftop runs, long exterior runs and runs on walls that see sun.

Key points

Schedule 80 is needed where the conduit is subject to physical damage, such as risers from grade where exposed.
PVC is not a grounding path. Pull a separate equipment grounding conductor.
Supports, bend limits and permitted trade sizes are in Article 352. Bends between pull points may not total more than 360°.
Use PVC cement and follow joint cure times, especially in cold weather.
Heat-bending needs a proper bender that warms the conduit evenly without scorching it.

Common mistakes

Using Schedule 40 in a parking lot riser or another exposed damage location.
Leaving out expansion fittings on long sunny runs, which then bow or pull apart.
Using plumbing pipe as conduit.
Filling Schedule 80 as if it had Schedule 40 inside diameter.

Governing standards: NEC Article 352 and Table 352.44; NEC Chapter 9 tables; UL 651; NEMA TC 2 (conduit); NEMA TC 3 (fittings).

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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