How Many 6 AWG THHN Wires Fit in 1" PVC Schedule 40 Conduit? (NEC Chart)

Per NEC Chapter 9 Table 4 and Table 5, 1" PVC Schedule 40 has a total internal area of 0.832 sq. in. (40% allowed fill = 0.333 sq. in.), allowing up to 6 6 AWG THHN conductors.

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Direct NEC Chapter 9 Answer: 6 Conductors Maximum (40% Fill)

6 Wires

Max 6 AWG THHN in 1" PVC Schedule 40

Standard Run (NEC 40% Fill = 0.333 sq in)

9 Wires

Nipple ≤ 24 Inches (60% Fill)

NEC Chapter 9 Note 4 Nipple Allowance

0.0507 sq in

Single 6 AWG THHN Area

Total 1" PVC Schedule 40 Area: 0.832 sq in

→ Open Interactive NEC Conduit Fill Calculator to mix wire gauges and grounds

1. NEC Conduit Fill Calculator (Chapter 9, Tables 1, 4 & 5)

Conduit Material

Conduit Trade Size

Conduit Nipple ≤ 24" (60% Fill)

Primary Wire Insulation

Primary Wire Gauge

Primary Wire Count

Secondary / Ground Insulation

Secondary / Ground Gauge

Secondary Wire Count

Recommended Job-Site Materials & Tools for This Run

Trade Size	Internal Dia.	Total Area	Bundle Fill %	Max Primary Wires	NEC Status