When installing 30-amp circuits for electric dryers, water heaters, or small air conditioning units, proper PVC conduit sizing for 10 AWG wire is critical for code compliance and safe operation. Understanding conduit fill requirements ensures your electrical installation meets National Electrical Code (NEC) standards while preventing wire damage and overheating issues.
This focused guide provides complete PVC conduit fill charts specifically for 10 AWG wire, including both Schedule 40 and Schedule 80 conduit, with practical examples for common residential and commercial applications.
Physical Properties:
Electrical Ratings (Copper):
Common Uses:
Based on NEC Chapter 9, Table 4 (40% fill for 3+ conductors):
| Conduit Size | Max 10 AWG THHN Conductors | Max 10 AWG THWN-2 Conductors | 40% Fill Area (sq in) |
|---|---|---|---|
| 1/2 inch | 6 | 6 | 0.114 |
| 3/4 inch | 10 | 10 | 0.203 |
| 1 inch | 16 | 16 | 0.333 |
| 1-1/4 inch | 29 | 29 | 0.581 |
| 1-1/2 inch | 40 | 40 | 0.794 |
| 2 inch | 65 | 65 | 1.316 |
Schedule 80 has thicker walls, reducing interior capacity:
| Conduit Size | Max 10 AWG THHN Conductors | Max 10 AWG THWN-2 Conductors | 40% Fill Area (sq in) |
|---|---|---|---|
| 1/2 inch | 4 | 4 | 0.087 |
| 3/4 inch | 8 | 8 | 0.164 |
| 1 inch | 13 | 13 | 0.275 |
| 1-1/4 inch | 24 | 24 | 0.495 |
| 1-1/2 inch | 33 | 33 | 0.677 |
| 2 inch | 56 | 56 | 1.127 |
info
💡 Key Insight: Schedule 80 PVC is typically used only where physical protection is required (exposed locations, direct burial without additional protection). For most residential installations, Schedule 40 is sufficient and provides greater wire capacity.
Circuit Requirements:
Step 1: Identify Wire Count Total conductors = 4 (2 hots + 1 neutral + 1 ground)
Step 2: Determine 10 AWG Area Each 10 AWG THHN = 0.00815 sq in Total area = 4 × 0.00815 = 0.0326 sq in
Step 3: Calculate Required Conduit Size Need conduit with 40% fill ≥ 0.0326 sq in
From chart:
Step 4: Apply Derating (if applicable) With 4 conductors, ampacity adjustment = 80% 30A × 0.80 = 24A (still adequate for 30A breaker protection)
Selection: 3/4 inch Schedule 40 PVC (provides margin for easier pulling)
warning
⚠️ Wire Pulling Tip: While 1/2 inch conduit is technically sufficient for 4 conductors of 10 AWG, using 3/4 inch conduit makes wire pulling significantly easier and reduces damage risk during installation. The minimal cost difference is worthwhile.
NEC Chapter 9, Table 4:
NEC 300.17:
NEC 310.15(C)(1):
When multiple conductors share a conduit:
| Number of Current-Carrying Conductors | Adjustment Factor |
|---|---|
| 4-6 | 80% |
| 7-9 | 70% |
| 10-20 | 50% |
| 21-30 | 45% |
Example Calculation:
| Application | Wire Configuration | Conductor Count | Minimum PVC Size |
|---|---|---|---|
| Electric Dryer | 10/3 w/ ground | 4 | 3/4 inch |
| Water Heater | 10/2 w/ ground | 3 | 1/2 inch |
| 30A Sub-panel Feed | 10/3 w/ ground | 4 | 3/4 inch |
| AC Disconnect | 10/2 w/ ground | 3 | 1/2 inch |
| Multiple Circuits | (2) 10/2 w/ ground | 6 | 3/4 inch |
Proper PVC conduit sizing for 10 AWG wire ensures NEC compliance, safe installation, and easy maintenance. For typical residential 30-amp circuits using 10/3 or 10/2 cable configurations, 3/4 inch Schedule 40 PVC conduit provides adequate capacity with comfortable pulling clearance.
Remember these key points:
For comprehensive conduit fill information including other wire sizes and detailed calculations, see our Complete Conduit Fill Chart and Calculator Guide.
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