3-1/2" PVC Sch 80 conduit fill

3-1/2" Rigid PVC conduit, Schedule 80 has an inside area of 8.688 sq in (3.326 in across). Three or more wires may take 40 % of it: 3.4752 sq in.

One wire, 53 %: 4.6046 sq in
Two wires, 31 %: 2.6933 sq in
Three or more, 40 %: 3.4752 sq in
Nipple, 60 %: 5.2128 sq in
Support: Every 7 ft, 3 ft from boxes
Sold in: 10 ft sticks

42 #4 THHN, the most it may hold, drawn to scale

How many wires fit in 3-1/2" PVC Sch 80

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	358	250	250
12 AWG	261	192	192
10 AWG	164	143	143
8 AWG	95	79	79
6 AWG	68	59	48
4 AWG	42	42	35
3 AWG	35	36	30
2 AWG	30	30	26
1 AWG	22	22	18
1/0 AWG	18	19	15
2/0 AWG	15	16	13
3/0 AWG	13	13	11
4/0 AWG	10	11	9
250 kcmil	8	9	7
300 kcmil	7	7	6
350 kcmil	6	6	6
400 kcmil	6	6	5
500 kcmil	5	5	4
600 kcmil	4	4	3
700 kcmil	3	3	3
750 kcmil	3	3	3
800 kcmil	3	3	3
900 kcmil	3	3	1
1000 kcmil	1	1	1

Smaller: 3" PVC Sch 80 Bigger: 4" PVC Sch 80

Other 3-1/2" conduit

Conduit	Inside area	#14	#12	#10	#8	#6
Rigid PVC conduit, Schedule 80	8.688	358	261	164	95	68
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 40	9.737	401	293	184	106	77
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 80

Schedule 80 has a thicker wall for where it can be hit, so it holds fewer wires than Schedule 40 of the same trade size. Support is the same as Schedule 40 (Table 352.30). See strap spacing and the fill rules.