How many 12 gauge wires fit in 1/2 inch EMT?

9 THHN. In 3/4 in. EMT, 16. Those are the fill limits; ampacity is a separate limit, and nine current-carrying 12 AWG conductors already cost 30 % of their ampacity (Table 310.15(C)(1)).

How many 14 AWG THHN in 1/2 EMT, and 10 AWG in 3/4 EMT?

12 × 14 AWG THHN in 1/2 in. EMT; 10 × 10 AWG THHN in 3/4 in. EMT.

Why does PVC Schedule 80 hold fewer wires than Schedule 40?

Same outside diameter, thicker wall, so a smaller inside area: 3/4 in. Schedule 40 takes 15 × 12 AWG THHN, Schedule 80 only 12.

Why do XHHW wires fit fewer than THHN?

XHHW insulation is thicker in the small sizes: 3/4 in. EMT takes 16 × 12 AWG THHN but 11 × 12 AWG XHHW-2. From 4 AWG up the two are closer, and the chart shows the exact figure for each.

Do ground wires count in conduit fill?

Yes. Chapter 9 Table 1 Note 3 counts equipment grounding and bonding conductors, insulated or bare, at their actual size. Add them in the conduit fill calculator; this chart covers one size only.

Table 1 sets 40 % of the conduit’s internal area for three or more conductors, 31 % for two and 53 % for one, so cables can be pulled without damage and heat can leave. Nipples of 24 in. or less may be filled to 60 % (Note 4).

How is a count like 16 decided when the division gives 16.01?

Note 7: when all conductors are the same size, a result with a decimal of 0.8 or more rounds up to the next whole number; anything below rounds down. The same rule decides the two-conductor and one-conductor cells, which is why some small conduits show 2 where the 31 % arithmetic alone gives 1.85.

Conduit fill chart: how many wires fit

The maximum number of conductors of one size in each conduit type and trade size. 1/2 in. EMT holds 9 × 12 AWG THHN and 3/4 in. EMT holds 16. Every count is computed from NEC Chapter 9 Table 4 (conduit internal area), Table 5 (conductor area) and Table 1 (the 53 / 31 / 40 % limits and the Note 7 rounding). For a mix of sizes, or to include the ground, use the conduit fill calculator.

Jump to: EMT · ENT · FMC · IMC · LFNC-A · LFNC-B · LFMC · RMC · PVC 80 · PVC 40 · PVC A · PVC EB · EMT XHHW-2 · PVC 40 XHHW-2

EMT: maximum THHN / THWN-2 conductors

Electrical metallic tubing (Art. 358). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″
14 AWG	12	22	35	61	84	138	241	364	476	608
12 AWG	9	16	26	45	61	101	176	266	347	443
10 AWG	5	10	16	28	38	63	111	167	219	279
8 AWG	3	6	9	16	22	36	64	96	126	161
6 AWG	2	4	7	12	16	26	46	69	91	116
4 AWG	1	2	4	7	10	16	28	43	56	71
3 AWG	1	1	3	6	8	13	24	36	47	60
2 AWG	1	1	3	5	7	11	20	30	40	51
1 AWG	1	1	1	4	5	8	15	22	29	37
1/0 AWG	1	1	1	3	4	7	12	19	25	32
2/0 AWG	0	1	1	2	3	6	10	16	20	26
3/0 AWG	0	1	1	1	3	5	8	13	17	22
4/0 AWG	0	1	1	1	2	4	7	11	14	18
250 kcmil	0	0	1	1	1	3	6	9	11	15
300 kcmil	0	0	1	1	1	3	5	7	10	13
350 kcmil	0	0	1	1	1	2	4	6	9	11
400 kcmil	0	0	0	1	1	1	4	6	8	10
500 kcmil	0	0	0	1	1	1	3	5	6	8

ENT: maximum THHN / THWN-2 conductors

Electrical nonmetallic tubing (Art. 362). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

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	2	4	7	9	16
3 AWG	1	1	3	6	8	13
2 AWG	1	1	3	5	7	11
1 AWG	1	1	1	3	5	8
1/0 AWG	1	1	1	3	4	7
2/0 AWG	0	1	1	2	3	6
3/0 AWG	0	1	1	1	3	5
4/0 AWG	0	1	1	1	2	4
250 kcmil	0	0	1	1	1	3
300 kcmil	0	0	1	1	1	3
350 kcmil	0	0	1	1	1	2
400 kcmil	0	0	0	1	1	1
500 kcmil	0	0	0	1	1	1

FMC: maximum THHN / THWN-2 conductors

Flexible metal conduit (Art. 348). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	3/8″	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″
14 AWG	4	13	22	33	52	76	135	202	291	396	518
12 AWG	3	9	16	24	38	56	98	147	212	289	378
10 AWG	1	6	10	15	24	35	62	93	134	182	238
8 AWG	1	3	6	9	14	20	35	53	77	105	137
6 AWG	1	2	4	6	10	14	25	38	55	76	99
4 AWG	0	1	2	4	6	9	16	24	34	46	61
3 AWG	0	1	1	3	5	7	13	20	29	39	51
2 AWG	0	1	1	3	4	6	11	17	24	33	43
1 AWG	0	1	1	1	3	4	8	12	18	24	32
1/0 AWG	0	1	1	1	2	4	7	10	15	20	27
2/0 AWG	0	0	1	1	1	3	6	9	12	17	22
3/0 AWG	0	0	1	1	1	2	5	7	10	14	18
4/0 AWG	0	0	1	1	1	1	4	6	8	12	15
250 kcmil	0	0	0	1	1	1	3	5	7	9	12
300 kcmil	0	0	0	1	1	1	3	4	6	8	11
350 kcmil	0	0	0	1	1	1	2	3	5	7	9
400 kcmil	0	0	0	0	1	1	1	3	5	6	8
500 kcmil	0	0	0	0	1	1	1	2	4	5	7

IMC: maximum THHN / THWN-2 conductors

Intermediate metal conduit (Art. 342). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″
14 AWG	14	24	39	68	91	149	211	326	436	562
12 AWG	10	17	29	49	67	109	154	238	318	410
10 AWG	6	11	18	31	42	69	97	150	200	258
8 AWG	3	6	10	18	24	39	56	86	115	149
6 AWG	2	4	7	13	17	28	40	62	83	107
4 AWG	1	3	4	8	11	17	25	38	51	66
3 AWG	1	2	4	6	9	15	21	32	43	56
2 AWG	1	1	3	5	7	12	17	27	36	47
1 AWG	1	1	2	4	5	9	13	20	27	35
1/0 AWG	1	1	1	3	4	8	11	17	23	29
2/0 AWG	1	1	1	3	4	6	9	14	19	24
3/0 AWG	0	1	1	2	3	5	7	12	16	20
4/0 AWG	0	1	1	1	2	4	6	9	13	17
250 kcmil	0	0	1	1	1	3	5	8	10	13
300 kcmil	0	0	1	1	1	3	4	7	9	12
350 kcmil	0	0	1	1	1	2	4	6	8	10
400 kcmil	0	0	1	1	1	2	3	5	7	9
500 kcmil	0	0	0	1	1	1	3	4	6	7

LFNC-A: maximum THHN / THWN-2 conductors

Liquidtight flexible nonmetallic conduit, Type A (Art. 356). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	3/8″	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″
14 AWG	8	13	22	35	62	83	138
12 AWG	5	9	16	25	45	60	100
10 AWG	3	6	10	16	28	38	63
8 AWG	1	3	6	9	16	22	36
6 AWG	1	2	4	6	12	16	26
4 AWG	1	1	2	4	7	9	16
3 AWG	1	1	1	3	6	8	13
2 AWG	1	1	1	3	5	7	11
1 AWG	0	1	1	1	4	5	8
1/0 AWG	0	1	1	1	3	4	7
2/0 AWG	0	0	1	1	2	3	6
3/0 AWG	0	0	1	1	1	3	5
4/0 AWG	0	0	1	1	1	2	4
250 kcmil	0	0	0	1	1	1	3
300 kcmil	0	0	0	1	1	1	3
350 kcmil	0	0	0	1	1	1	2
400 kcmil	0	0	0	0	1	1	1
500 kcmil	0	0	0	0	1	1	1

LFNC-B: maximum THHN / THWN-2 conductors

Liquidtight flexible nonmetallic conduit, Type B (Art. 356). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	3/8″	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″
14 AWG	8	13	22	36	63	81	134
12 AWG	5	9	16	26	46	59	97
10 AWG	3	6	10	16	29	37	61
8 AWG	1	3	6	9	16	21	35
6 AWG	1	2	4	7	12	15	25
4 AWG	1	1	2	4	7	9	15
3 AWG	1	1	1	3	6	8	13
2 AWG	1	1	1	3	5	7	11
1 AWG	0	1	1	1	4	5	8
1/0 AWG	0	1	1	1	3	4	7
2/0 AWG	0	0	1	1	2	3	6
3/0 AWG	0	0	1	1	1	3	5
4/0 AWG	0	0	1	1	1	2	4
250 kcmil	0	0	0	1	1	1	3
300 kcmil	0	0	0	1	1	1	3
350 kcmil	0	0	0	1	1	1	2
400 kcmil	0	0	0	0	1	1	1
500 kcmil	0	0	0	0	1	1	1

LFMC: maximum THHN / THWN-2 conductors

Liquidtight flexible metal conduit (Art. 350). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	3/8″	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″
14 AWG	8	13	22	36	63	81	134	201	308	401	523
12 AWG	5	9	16	26	46	59	97	146	225	292	381
10 AWG	3	6	10	16	29	37	61	92	141	184	240
8 AWG	1	3	6	9	16	21	35	53	81	106	138
6 AWG	1	2	4	7	12	15	25	38	59	76	100
4 AWG	1	1	2	4	7	9	15	23	36	47	61
3 AWG	1	1	1	3	6	8	13	20	30	40	52
2 AWG	1	1	1	3	5	7	11	17	26	33	44
1 AWG	0	1	1	1	4	5	8	12	19	25	32
1/0 AWG	0	1	1	1	3	4	7	10	16	21	27
2/0 AWG	0	0	1	1	2	3	6	8	13	17	23
3/0 AWG	0	0	1	1	1	3	5	7	11	14	19
4/0 AWG	0	0	1	1	1	2	4	6	9	12	15
250 kcmil	0	0	0	1	1	1	3	5	7	10	12
300 kcmil	0	0	0	1	1	1	3	4	6	8	11
350 kcmil	0	0	0	1	1	1	2	3	5	7	9
400 kcmil	0	0	0	0	1	1	1	3	5	6	8
500 kcmil	0	0	0	0	1	1	1	2	4	5	7

RMC: maximum THHN / THWN-2 conductors

Rigid metal conduit (Art. 344). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″	5″	6″
14 AWG	13	22	36	63	85	140	200	309	412	531	833	1202
12 AWG	9	16	26	46	62	102	146	225	301	387	608	877
10 AWG	6	10	17	29	39	64	92	142	189	244	383	552
8 AWG	3	6	9	16	22	37	53	82	109	140	221	318
6 AWG	2	4	7	12	16	27	38	59	79	101	159	230
4 AWG	1	2	4	7	10	16	23	36	48	62	98	141
3 AWG	1	1	3	6	8	14	20	31	41	53	83	120
2 AWG	1	1	3	5	7	11	17	26	34	44	70	100
1 AWG	1	1	1	4	5	8	12	19	25	33	51	74
1/0 AWG	1	1	1	3	4	7	10	16	21	27	43	63
2/0 AWG	0	1	1	2	3	6	8	13	18	23	36	52
3/0 AWG	0	1	1	1	3	5	7	11	15	19	30	43
4/0 AWG	0	1	1	1	2	4	6	9	12	16	25	36
250 kcmil	0	0	1	1	1	3	5	7	10	13	20	29
300 kcmil	0	0	1	1	1	3	4	6	8	11	17	25
350 kcmil	0	0	1	1	1	2	3	5	7	10	15	22
400 kcmil	0	0	1	1	1	2	3	5	7	8	13	20
500 kcmil	0	0	0	1	1	1	2	4	5	7	11	16

PVC 80: maximum THHN / THWN-2 conductors

Rigid PVC conduit, Schedule 80 (Art. 352). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″	5″	6″
14 AWG	9	17	28	51	70	118	170	265	358	464	736	1055
12 AWG	6	12	20	37	51	86	124	193	261	338	537	770
10 AWG	4	7	13	23	32	54	78	122	164	213	338	485
8 AWG	2	4	7	13	18	31	45	70	95	123	195	279
6 AWG	1	3	5	9	13	22	32	51	68	89	141	202
4 AWG	1	1	3	6	8	14	20	31	42	54	86	124
3 AWG	1	1	3	5	7	12	17	26	35	46	73	105
2 AWG	1	1	2	4	6	10	14	22	30	39	61	88
1 AWG	0	1	1	3	4	7	10	16	22	29	45	65
1/0 AWG	0	1	1	2	3	6	9	14	18	24	38	55
2/0 AWG	0	1	1	1	3	5	7	11	15	20	32	46
3/0 AWG	0	1	1	1	2	4	6	9	13	17	26	38
4/0 AWG	0	0	1	1	1	3	5	8	10	14	22	31
250 kcmil	0	0	1	1	1	3	4	6	8	11	18	25
300 kcmil	0	0	0	1	1	2	3	5	7	9	15	22
350 kcmil	0	0	0	1	1	1	3	5	6	8	13	19
400 kcmil	0	0	0	1	1	1	3	4	6	7	12	17
500 kcmil	0	0	0	1	1	1	2	3	5	6	10	14

PVC 40: maximum THHN / THWN-2 conductors

Rigid PVC conduit, Schedule 40, and HDPE (Art. 352, 353). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″	5″	6″
14 AWG	11	21	34	60	82	135	193	299	401	517	815	1178
12 AWG	8	15	25	43	59	99	141	218	293	377	594	859
10 AWG	5	9	15	27	37	62	89	137	184	238	374	541
8 AWG	3	5	9	16	21	36	51	79	106	137	216	312
6 AWG	1	4	6	11	15	26	37	57	77	99	156	225
4 AWG	1	2	4	7	9	16	22	35	47	61	96	138
3 AWG	1	1	3	6	8	13	19	30	40	51	81	117
2 AWG	1	1	3	5	7	11	16	25	33	43	68	98
1 AWG	1	1	1	3	5	8	12	18	25	32	50	73
1/0 AWG	1	1	1	3	4	7	10	15	21	27	42	61
2/0 AWG	0	1	1	2	3	6	8	13	17	22	35	51
3/0 AWG	0	1	1	1	3	5	7	11	14	18	29	42
4/0 AWG	0	1	1	1	2	4	6	9	12	15	24	35
250 kcmil	0	0	1	1	1	3	4	7	10	12	20	28
300 kcmil	0	0	1	1	1	3	4	6	8	11	17	24
350 kcmil	0	0	1	1	1	2	3	5	7	9	15	21
400 kcmil	0	0	0	1	1	1	3	5	6	8	13	19
500 kcmil	0	0	0	1	1	1	2	4	5	7	11	16

PVC A: maximum THHN / THWN-2 conductors

Rigid PVC conduit, Type A (Art. 352). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″
14 AWG	16	27	44	73	96	150	225	338	441	566
12 AWG	11	19	32	53	70	109	164	246	321	412
10 AWG	7	12	20	33	44	69	103	155	202	260
8 AWG	4	7	12	19	25	40	59	89	117	150
6 AWG	3	5	8	14	18	28	43	64	84	108
4 AWG	1	3	5	8	11	17	26	39	52	66
3 AWG	1	2	4	7	9	15	22	33	44	56
2 AWG	1	1	3	6	8	12	19	28	37	47
1 AWG	1	1	2	4	6	9	14	21	27	35
1/0 AWG	1	1	2	4	5	8	11	17	23	29
2/0 AWG	1	1	1	3	4	6	10	14	19	24
3/0 AWG	0	1	1	2	3	5	8	12	16	20
4/0 AWG	0	1	1	1	3	4	6	10	13	17
250 kcmil	0	1	1	1	2	3	5	8	10	14
300 kcmil	0	0	1	1	1	3	4	7	9	12
350 kcmil	0	0	1	1	1	2	4	6	8	10
400 kcmil	0	0	1	1	1	2	3	5	7	9
500 kcmil	0	0	1	1	1	1	3	4	6	7

PVC EB: maximum THHN / THWN-2 conductors

Rigid PVC conduit, Type EB (Art. 352). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	2″	3″	3 1/2″	4″	5″	6″
14 AWG	159	359	468	595	915	1300
12 AWG	116	262	342	434	667	948
10 AWG	73	165	215	274	420	597
8 AWG	42	95	124	158	242	344
6 AWG	30	68	89	114	175	248
4 AWG	19	42	55	70	107	153
3 AWG	16	36	46	59	91	129
2 AWG	13	30	39	50	76	109
1 AWG	10	22	29	37	57	80
1/0 AWG	8	18	24	31	48	68
2/0 AWG	7	15	20	26	40	56
3/0 AWG	5	13	17	21	33	47
4/0 AWG	4	10	14	18	27	39
250 kcmil	4	8	11	14	22	31
300 kcmil	3	7	10	12	19	27
350 kcmil	3	6	8	11	17	24
400 kcmil	2	6	7	10	15	21
500 kcmil	1	5	6	8	12	18

EMT: maximum XHHW-2 conductors

Electrical metallic tubing (Art. 358). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″
14 AWG	8	15	25	43	58	96	168	254	332	424
12 AWG	6	11	19	33	45	74	129	195	255	326
10 AWG	5	8	14	24	33	55	96	145	190	243
8 AWG	2	5	8	13	18	30	53	81	105	135
6 AWG	1	3	6	10	14	22	39	60	78	100
4 AWG	1	2	4	7	10	16	28	43	56	72
3 AWG	1	1	3	6	8	14	24	36	48	61
2 AWG	1	1	3	5	7	11	20	31	40	51
1 AWG	1	1	1	4	5	8	15	23	30	38
1/0 AWG	1	1	1	3	4	7	13	19	25	32
2/0 AWG	0	1	1	2	3	6	10	16	21	27
3/0 AWG	0	1	1	1	3	5	9	13	17	22
4/0 AWG	0	1	1	1	2	4	7	11	14	18
250 kcmil	0	0	1	1	1	3	6	9	12	15
300 kcmil	0	0	1	1	1	3	5	8	10	13
350 kcmil	0	0	1	1	1	2	4	7	9	11
400 kcmil	0	0	0	1	1	1	4	6	8	10
500 kcmil	0	0	0	1	1	1	3	5	6	8

PVC 40: maximum XHHW-2 conductors

Rigid PVC conduit, Schedule 40, and HDPE (Art. 352, 353). Trade sizes across, conductor size down; a 0 means not even one conductor fits.

Size	1/2″	3/4″	1″	1 1/4″	1 1/2″	2″	2 1/2″	3″	3 1/2″	4″	5″	6″
14 AWG	8	14	24	42	57	94	135	209	280	361	568	822
12 AWG	6	11	18	32	44	72	103	160	215	277	436	631
10 AWG	4	8	13	24	32	54	77	119	160	206	325	470
8 AWG	2	4	7	13	18	30	43	66	89	115	181	261
6 AWG	1	3	5	10	13	22	32	49	66	85	134	193
4 AWG	1	2	4	7	9	16	23	35	48	61	97	140
3 AWG	1	1	3	6	8	13	19	30	40	52	82	118
2 AWG	1	1	3	5	7	11	16	25	34	44	69	99
1 AWG	1	1	1	3	5	8	12	19	25	32	51	74
1/0 AWG	1	1	1	3	4	7	10	16	21	27	43	62
2/0 AWG	0	1	1	2	3	6	8	13	17	23	36	52
3/0 AWG	0	1	1	1	3	5	7	11	14	19	30	43
4/0 AWG	0	1	1	1	2	4	6	9	12	15	24	35
250 kcmil	0	0	1	1	1	3	5	7	10	13	20	29
300 kcmil	0	0	1	1	1	3	4	6	8	11	17	25
350 kcmil	0	0	1	1	1	2	3	5	7	9	15	22
400 kcmil	0	0	0	1	1	1	3	5	6	8	13	19
500 kcmil	0	0	0	1	1	1	2	4	5	7	11	16

How the counts were made and checked

For each cell: the count at 40 % of the Table 4 total area, rounded by Note 7; if that is fewer than three, two conductors are tested at 31 % and one at 53 %, with the same rounding. The conduit and conductor areas come from NEC 2017 (NFPA 70-2017), Chapter 9 Tables 1, 4, 5 and 5A; identical to 2011.

Informative Annex C prints the same kind of chart. Every THHN and XHHW cell in the 2017 Annex C Tables C.1 to C.13 (all but C.7, LFNC-C, which this site does not carry), 4,865 in all, was compared with this computation: 4,864 agree. The one that does not is 1/0 XHHW in 1/2 in. ENT, where Annex C prints 0 and the arithmetic gives 1 (one conductor at 53 % is 0.95 of the allowance, which Note 7 rounds to one). Annex C is informative; the Chapter 9 tables are the requirement.

A full conduit is not the only limit. Ten to twenty current-carrying conductors take 50 % of their table ampacity, and the bends between pull points may not exceed 360° in total. Compact-stranded conductors (Table 5A) and fixture wires are not in this chart.

Questions people ask

How many 12 gauge wires fit in 1/2 inch EMT?: 9 THHN. In 3/4 in. EMT, 16. Those are the fill limits; ampacity is a separate limit, and nine current-carrying 12 AWG conductors already cost 30 % of their ampacity (Table 310.15(C)(1)).
How many 14 AWG THHN in 1/2 EMT, and 10 AWG in 3/4 EMT?: 12 × 14 AWG THHN in 1/2 in. EMT; 10 × 10 AWG THHN in 3/4 in. EMT.
Why does PVC Schedule 80 hold fewer wires than Schedule 40?: Same outside diameter, thicker wall, so a smaller inside area: 3/4 in. Schedule 40 takes 15 × 12 AWG THHN, Schedule 80 only 12.
Why do XHHW wires fit fewer than THHN?: XHHW insulation is thicker in the small sizes: 3/4 in. EMT takes 16 × 12 AWG THHN but 11 × 12 AWG XHHW-2. From 4 AWG up the two are closer, and the chart shows the exact figure for each.
Do ground wires count in conduit fill?: Yes. Chapter 9 Table 1 Note 3 counts equipment grounding and bonding conductors, insulated or bare, at their actual size. Add them in the conduit fill calculator; this chart covers one size only.
Why 40 percent?: Table 1 sets 40 % of the conduit’s internal area for three or more conductors, 31 % for two and 53 % for one, so cables can be pulled without damage and heat can leave. Nipples of 24 in. or less may be filled to 60 % (Note 4).
How is a count like 16 decided when the division gives 16.01?: Note 7: when all conductors are the same size, a result with a decimal of 0.8 or more rounds up to the next whole number; anything below rounds down. The same rule decides the two-conductor and one-conductor cells, which is why some small conduits show 2 where the 31 % arithmetic alone gives 1.85.