ENT Conduit Fill Chart

Electrical Nonmetallic Tubing — NEC Article 362. Corrugated pliable plastic tubing (“smurf tube”), bent by hand and used inside walls, above suspended ceilings and encased in concrete slabs. Current tables give it the same internal dimensions as Schedule 40 PVC.

1/2-inch ENT holds 8 #12 THHN conductors; 3/4-inch holds 15. Counts assume 40% fill with all conductors the same size.

ENT fill calculator

Conduit type

Trade size

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

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ENT sizes

One page per trade size, with counts for every insulation type side by side.

ENT fill chart — THHN / THWN-2

Thermoplastic insulation with a nylon jacket. The thinnest common building wire, so it gives the highest conductor counts. Nearly all pulled wire sold in North America is dual-rated THHN/THWN-2.

Maximum THHN conductors in ENT — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
14 AWG	11	21	34	60	82	135
12 AWG	8	15	25	43	59	99
10 AWG	5	9	15	27	37	62
8 AWG	3	5	9	16	21	36
6 AWG	1	4	6	11	15	26
4 AWG	1	1	4	7	9	16
3 AWG	1	1	3	6	8	13
2 AWG	1	1	3	5	7	11
1 AWG	—	1	1	3	5	8
1/0 AWG	—	1	1	3	4	7
2/0 AWG	—	1	1	2	3	6
3/0 AWG	—	1	1	1	3	5
4/0 AWG	—	—	1	1	1	4
250 kcmil	—	—	1	1	1	3
300 kcmil	—	—	—	1	1	3
350 kcmil	—	—	—	1	1	1
400 kcmil	—	—	—	1	1	1
500 kcmil	—	—	—	1	1	1
600 kcmil	—	—	—	—	1	1
700 kcmil	—	—	—	—	1	1
750 kcmil	—	—	—	—	1	1
800 kcmil	—	—	—	—	—	1
900 kcmil	—	—	—	—	—	1
1000 kcmil	—	—	—	—	—	1

ENT fill chart — XHHW / XHHW-2

Cross-linked polyethylene (XLPE) insulation, no nylon jacket. Standard for aluminum feeders and common for larger copper feeders. Slightly fatter than THHN in small sizes, slightly thinner above 4 AWG.

Maximum XHHW conductors in ENT — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
14 AWG	8	14	24	42	57	94
12 AWG	6	11	18	32	44	72
10 AWG	4	8	13	24	32	54
8 AWG	2	4	7	13	18	30
6 AWG	1	3	5	10	13	22
4 AWG	1	1	4	7	9	16
3 AWG	1	1	3	6	8	13
2 AWG	1	1	3	5	7	11
1 AWG	—	1	1	3	5	8
1/0 AWG	—	1	1	3	4	7
2/0 AWG	—	1	1	2	3	6
3/0 AWG	—	1	1	1	3	5
4/0 AWG	—	—	1	1	1	4
250 kcmil	—	—	1	1	1	3
300 kcmil	—	—	—	1	1	3
350 kcmil	—	—	—	1	1	1
400 kcmil	—	—	—	1	1	1
500 kcmil	—	—	—	1	1	1
600 kcmil	—	—	—	—	1	1
700 kcmil	—	—	—	—	1	1
750 kcmil	—	—	—	—	—	1
800 kcmil	—	—	—	—	—	1
900 kcmil	—	—	—	—	—	1
1000 kcmil	—	—	—	—	—	1

ENT fill chart — THW / THHW / TW

Older thick-wall thermoplastic insulation without a nylon jacket. Rarely installed new, but it is what you will find in many existing conduits, and it takes considerably more room than THHN.

Maximum THW conductors in ENT — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
14 AWG	8	14	24	42	57	94
12 AWG	6	11	18	32	44	72
10 AWG	4	8	13	24	32	54
8 AWG	2	4	7	13	18	30
6 AWG	1	2	4	8	11	18
4 AWG	1	1	3	6	8	13
3 AWG	1	1	3	5	7	11
2 AWG	1	1	1	4	6	10
1 AWG	—	1	1	3	4	7
1/0 AWG	—	1	1	2	3	6
2/0 AWG	—	1	1	1	3	5
3/0 AWG	—	—	1	1	1	4
4/0 AWG	—	—	1	1	1	3
250 kcmil	—	—	—	1	1	3
300 kcmil	—	—	—	1	1	1
350 kcmil	—	—	—	1	1	1
400 kcmil	—	—	—	1	1	1
500 kcmil	—	—	—	—	1	1
600 kcmil	—	—	—	—	1	1
700 kcmil	—	—	—	—	—	1
750 kcmil	—	—	—	—	—	1
800 kcmil	—	—	—	—	—	1
900 kcmil	—	—	—	—	—	1
1000 kcmil	—	—	—	—	—	1

ENT fill chart — RHH / RHW-2

Thermoset rubber-type insulation with an outer covering. The bulkiest of the common types; counts drop to roughly half of THHN in small conduit.

Maximum RHW conductors in ENT — 40% fill (53% for one wire, 31% for two)
Wire size	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"
14 AWG	4	7	11	20	27	45
12 AWG	3	5	9	16	22	37
10 AWG	2	4	7	13	18	30
8 AWG	1	1	4	7	9	15
6 AWG	1	1	3	5	7	12
4 AWG	1	1	1	4	6	10
3 AWG	—	1	1	4	5	8
2 AWG	—	1	1	3	4	7
1 AWG	—	1	1	1	3	5
1/0 AWG	—	—	1	1	2	4
2/0 AWG	—	—	1	1	1	3
3/0 AWG	—	—	1	1	1	3
4/0 AWG	—	—	—	1	1	2
250 kcmil	—	—	—	1	1	1
300 kcmil	—	—	—	1	1	1
350 kcmil	—	—	—	—	1	1
400 kcmil	—	—	—	—	1	1
500 kcmil	—	—	—	—	1	1
600 kcmil	—	—	—	—	—	1
700 kcmil	—	—	—	—	—	1
750 kcmil	—	—	—	—	—	1
800 kcmil	—	—	—	—	—	1
900 kcmil	—	—	—	—	—	1
1000 kcmil	—	—	—	—	—	—

ENT internal diameter and area

ENT internal dimensions and allowable fill area
Trade size	Metric designator	Internal dia. (in)	Total area (in²)	1 wire — 53%	2 wires — 31%	Over 2 — 40%	Nipple — 60%
1/2"	16	0.602	0.285	0.151	0.088	0.114	0.171
3/4"	21	0.804	0.508	0.269	0.157	0.203	0.305
1"	27	1.029	0.832	0.441	0.258	0.333	0.499
1-1/4"	35	1.360	1.453	0.770	0.450	0.581	0.872
1-1/2"	41	1.590	1.986	1.053	0.616	0.794	1.192
2"	53	2.047	3.291	1.744	1.020	1.316	1.975

Fill limits that apply

Allowable conduit fill (Chapter 9, Table 1 and its notes)
Conductors in the raceway	Maximum fill	Why
1	53%	A single conductor cannot jam, so more of the area can be used.
2	31%	Two conductors lie side by side and wedge easily in bends, so the limit is lowest.
3 or more	40%	The everyday limit. Leaves room to pull and for heat to escape.
Nipple ≤ 24 in.	60%	Short sections between boxes or enclosures; derating for conductor count does not apply either.

Frequently asked questions

How many #12 wires can I put in 1/2-inch ENT?

8 conductors of 12 AWG THHN/THWN-2, or 6 of the thicker THW. In 3/4-inch ENT the count rises to 15 THHN.

How many #10 wires fit in 1/2-inch ENT?

5 conductors of 10 AWG THHN in 1/2-inch, and 9 in 3/4-inch.

What is the inside diameter of 3/4-inch ENT?

0.804 inches, giving a total internal area of 0.508 in² and 0.203 in² of usable area at 40% fill.

What is the largest wire that fits in 2-inch ENT?

2-inch ENT holds 1 conductors of 500 kcmil THHN or 1 of 1000 kcmil.

NECTables.com is an independent reference and is not affiliated with, endorsed by, or a substitute for the National Fire Protection Association (NFPA). NEC® and National Electrical Code® are registered trademarks of the NFPA. Values shown are commonly published engineering data and independent calculations based on the methods of NFPA 70; they are not a reproduction of the Code. Always confirm against the edition adopted in your jurisdiction, including local amendments, and consult a licensed electrician or engineer before doing electrical work.