4-inch PVC Schedule 40 Conduit Fill

Wire capacity of trade size 4 (metric designator 103) Rigid PVC Conduit, Schedule 40, for THHN, XHHW, THW and RHW conductors from 14 AWG to 1000 kcmil.

4-inch PVC Schedule 40 holds 99 × #6, 61 × #4, 43 × #2 or 27 × 1/0 AWG THHN conductors at 40% fill. Internal area: 12.554 in²; usable at 40%: 5.022 in².

Internal diameter

3.998 in · 101.5 mm

Total area

12.554 in² · 8099 mm²

40% fill (3+ wires)

5.022 in²

31% / 53% (2 / 1 wire)

3.892 / 6.654 in²

Maximum conductors in 4-inch PVC Schedule 40
Wire size	THHN	XHHW	THW	RHW	THHN in a nipple (60%)	THHN area (in²)
14 AWG	517	361	361	171	776	0.0097
12 AWG	377	277	277	142	566	0.0133
10 AWG	238	206	206	115	357	0.0211
8 AWG	137	115	115	60	206	0.0366
6 AWG	99	85	69	48	148	0.0507
4 AWG	61	61	51	37	91	0.0824
3 AWG	51	52	44	33	77	0.0973
2 AWG	43	44	37	28	65	0.1158
1 AWG	32	32	26	19	48	0.1562
1/0 AWG	27	27	22	16	40	0.1855
2/0 AWG	22	23	19	14	34	0.2223
3/0 AWG	18	19	16	12	28	0.2679
4/0 AWG	15	15	13	10	23	0.3237
250 kcmil	12	13	11	8	19	0.3970
300 kcmil	11	11	9	7	16	0.4608
350 kcmil	9	9	8	6	14	0.5242
400 kcmil	8	8	7	6	13	0.5863
500 kcmil	7	7	6	5	10	0.7073
600 kcmil	5	5	5	4	8	0.8676
700 kcmil	5	5	4	3	7	0.9887
750 kcmil	4	4	4	3	7	1.0496
800 kcmil	4	4	4	3	6	1.1085
900 kcmil	4	4	3	3	6	1.2311
1000 kcmil	3	3	3	3	5	1.3478

Mixed wire sizes? Calculate it

Conduit type

Trade size

Run length Nipple, 24 in. or shorter (60%)

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4-inch conduit: PVC Schedule 40 vs other types

Trade size is nominal. The real inside diameter, and so the wire count, changes with the wall thickness of each raceway type.

4-inch trade size across conduit types
Conduit type	ID (in)	Area (in²)	40% (in²)	#12 THHN	#10 THHN	#6 THHN
EMT	4.334	14.753	5.901	443	279	116
PVC Schedule 40	3.998	12.554	5.022	377	238	99
PVC Schedule 80	3.786	11.258	4.503	338	213	89
Rigid Metal Conduit	4.050	12.882	5.153	387	244	101
IMC	4.166	13.631	5.452	410	258	107
Flexible Metal Conduit	4.000	12.566	5.026	378	238	99
Liquidtight Flexible Metal Conduit	4.020	12.692	5.077	381	240	100

Other PVC Schedule 40 sizes

Frequently asked questions

How many #12 wires fit in 4-inch PVC Schedule 40?

377 conductors of 12 AWG THHN/THWN-2 at the 40% fill limit. With thicker THW or XHHW insulation the count is 277.

What is the inside diameter and area of 4-inch PVC Schedule 40?

The internal diameter is 3.998 in. (101.5 mm) and the total cross-sectional area is 12.554 in². The usable area is 5.022 in² at 40% fill, 3.892 in² for two wires and 6.654 in² for one.

What is the largest wire I can pull three of in 4-inch PVC Schedule 40?

1000 kcmil THHN: 3 conductors fit at 40% fill. That is three current-carrying conductors with no ground; add the ground’s area and check again with the calculator if you need one.

Can I really load it with that many conductors?

For space, yes. But 377 current-carrying conductors in one raceway means heavy ampacity derating — 10 to 20 conductors are adjusted to 50% of their table ampacity. Fill tells you what fits; derating tells you what it can carry.

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