What is PVC Schedule 80 Conduit?
PVC Schedule 80 is heavy-wall rigid PVC raceway required by NEC 352.10(B) where exposed conduit is subject to physical damage. Same OD as Schedule 40.
PVC Schedule 80 conduit is the heavy-wall version of rigid polyvinyl chloride raceway. It shares the same outer diameter as Schedule 40 — so all fittings interchange — but its thicker wall reduces the interior cross-section. NEC Article 352 covers both schedules, and NEC 352.10(B) requires Schedule 80 anywhere exposed conduit is subject to physical damage. Schedule 80 is identified by the "Sch 80" marking and is gray (sunlight-resistant) like Schedule 40.
Construction
- Material: Rigid PVC
- Wall thickness (1"): Approximately 0.179 inch vs Sch 40's 0.133 inch
- Outer diameter: Identical to Schedule 40 at every trade size
- Color: Gray (UV-resistant compound)
- Joining: Solvent-welded with PVC cement
- Length: 10 ft and 20 ft sticks with bell-end couplings
Because the OD is unchanged, the wall thickness has to come from somewhere — the interior bore is smaller. That has direct consequences for conduit fill.
Interior cross-section (NEC Chapter 9 Table 4)
| Trade size | Sch 80 area in² | Sch 40 area in² | Loss vs Sch 40 |
|---|---|---|---|
| 1/2" | 0.217 | 0.285 | -24% |
| 3/4" | 0.409 | 0.508 | -19% |
| 1" | 0.688 | 0.832 | -17% |
| 1-1/4" | 1.237 | 1.453 | -15% |
| 1-1/2" | 1.711 | 1.986 | -14% |
| 2" | 2.874 | 3.291 | -13% |
| 2-1/2" | 4.119 | 4.695 | -12% |
| 3" | 6.442 | 7.268 | -11% |
| 3-1/2" | 8.688 | 9.737 | -11% |
| 4" | 11.258 | 12.554 | -10% |
A 2" Schedule 80 with 12 AWG THHN holds about 86 conductors at 40% fill versus 99 in 2" Schedule 40. Confirm with the PVC conduit fill chart before sizing.
NEC code reference
- NEC 352.10(B) — required where rigid PVC conduit is exposed to physical damage
- NEC 352.10(C) — permitted where Schedule 40 is permitted, with no additional restrictions
- NEC 352.30(B) — same support spacing rules as Schedule 40
- NEC 352.44 — expansion fittings required by length and temperature change
In practice, "physical damage" is interpreted as locations like building exteriors below 8 ft, parking structures, mechanical rooms, and rooftops with traffic. AHJ judgment applies.
Common applications
- Risers from underground to outdoor disconnects and meter sockets
- Wall transitions from grade to first-floor electrical equipment
- Exposed runs in mechanical/equipment rooms
- Site lighting bollards (the lower 8 ft above grade)
- Solar array DC home runs exposed on roof racking
- Pool and spa equipment-pad conduit stub-ups
Trade-offs vs Schedule 40
| Property | Sch 80 | Sch 40 |
|---|---|---|
| Wall thickness | Thicker (~0.179" at 1") | Thinner (~0.133" at 1") |
| Interior area | Smaller | Larger |
| Cost per ft | ~30–40% higher | Lower |
| Physical-damage rating | Required where exposed | Insufficient |
| Underground use | Yes | Yes (standard) |
| Fitting compatibility | Same OD — interchanges | Same OD — interchanges |
A common field shortcut: install Schedule 40 underground, transition to Schedule 80 at the elbow stub-up exposed to grade, then continue in Schedule 80 up to the disconnect. Same fittings, no special couplings needed.
Bending and expansion
Schedule 80 field-bends with a heat box, same as Schedule 40, but takes longer to reach forming temperature due to the extra wall. Expansion characteristics are identical — about 4 inches per 100 ft per 100°F. Use NEC Table 352.44(A) to size expansion fittings.
Quick reference
- Article: NEC 352
- Required by: NEC 352.10(B) for physical damage
- Same OD as Schedule 40: yes
- EGC qualifier: no — pull a separate EGC
- Color: gray
- Joining: solvent weld