3-1/2" PVC Sch 40 conduit fill

3-1/2" Rigid PVC conduit, Schedule 40 has an inside area of 9.737 sq in (3.521 in across). Three or more wires may take 40 % of it: 3.8948 sq in.

One wire, 53 %: 5.1606 sq in
Two wires, 31 %: 3.0185 sq in
Three or more, 40 %: 3.8948 sq in
Nipple, 60 %: 5.8422 sq in
Support: Every 7 ft, 3 ft from boxes
Sold in: 10 ft sticks

47 #4 THHN, the most it may hold, drawn to scale

How many wires fit in 3-1/2" PVC Sch 40

All wires the same size and type, by Annex C's method. For a mix of sizes, open the calculator.

Wire size	THHN/THWN-2	XHHW-2	THW/THW-2
14 AWG	401	280	280
12 AWG	293	215	215
10 AWG	184	160	160
8 AWG	106	89	89
6 AWG	77	66	53
4 AWG	47	48	40
3 AWG	40	40	34
2 AWG	33	34	29
1 AWG	25	25	20
1/0 AWG	21	21	17
2/0 AWG	17	17	15
3/0 AWG	14	14	12
4/0 AWG	12	12	10
250 kcmil	10	10	8
300 kcmil	8	8	7
350 kcmil	7	7	6
400 kcmil	6	6	6
500 kcmil	5	5	5
600 kcmil	4	4	4
700 kcmil	4	4	3
750 kcmil	3	3	3
800 kcmil	3	3	3
900 kcmil	3	3	3
1000 kcmil	3	3	2

Smaller: 3" PVC Sch 40 Bigger: 4" PVC Sch 40

Other 3-1/2" conduit

Conduit	Inside area	#14	#12	#10	#8	#6
Rigid PVC conduit, Schedule 40	9.737	401	293	184	106	77
Electrical metallic tubing	11.545	476	347	219	126	91
Intermediate metal conduit	10.584	436	318	200	115	83
Rigid metal conduit (RMC, GRC)	10.010	412	301	189	109	79
Rigid PVC conduit, Schedule 80	8.688	358	261	164	95	68
Flexible metal conduit (FMC, Greenfield)	9.621	396	289	182	105	76
Liquidtight flexible metal conduit (LFMC)	9.731	401	292	184	106	76

About PVC Sch 40

Schedule 40 is the standard PVC wall. Support spacing gets wider as the size goes up (Table 352.30), and long runs in the sun need expansion fittings (352.44). See strap spacing and the fill rules.