28 Wiring Inspection

Tabl e 3 Tabl e 310- 16
Allowable Ampacities of Insulated Conductors Rated 0-2000 Vol ts,6 0° to 90°C (140° to 194°F)1
NotMore than Three Conductorsin Raceway or Cable orEarth (Directly Buried),based on Ambient Temperatureof 30° (86°F)
Size Temperature Ratingof Conductor. See Table 310-13. Size
AWG
kcmil
60°C
(140°F) 75°C
(167°F) 90°C
(194°F) 60°C
(140°F) 75°C
(167°F) 90°C
(194°F)
AWG
kcmil
Types
TW*
UF*
Types
FEPW*,
RH, RHW*,
THHW*,
THW*,
THWN*,
XHHW*,
USE*, ZW*
Types
TBS, SA, SIS
FEP*, FEPB*, MI,
RHH*, RHW-2,
THHN*, THHW*,
THW-2,THWN-2,
USE-2, XHH, XHHW*
XHHW-2, ZW-2
Types
TW*
UF*
Types
RH*, RHW*,
THHW*,
THW*,
THWN*,
XHHW*,
USE*
Types
TBS, SA, SIS,
THHN*, THHW*,
THW-2,THWN-2,
RHH*, RHW-2,
USE-2,
XHH, XHHW*,
XHHW-2, ZW-2

Copper Aluminum or Copper-Clad Aluminum

18
16
14
12
10
8
.......
.......
20†
25†
30
40
.......
.......
20†
25†
35†
50
14
18
25†
30†
40†
55
.......
.......
.......
20†
25
30
.......
.......
.......
20†
30†
40
.......
.......
.......
25†
35†
45
.......
.......
.......
12
10
8
6
4
3
2
1
55
70
85
95
110
65
85
100
115
130
75
95
110
130
150
40
55
65
75
85
50
65
75
90
100
60
75
85
100
115
6
4
3
2
1
1/0
2/0
3/0
4/0
125
145
165
195
150
175
200
230
170
195
225
260
100
115
130
150
120
135
155
180
135
150
175
205
1/0
2/0
3/0
4/0
250
300
350
400
500
215
240
260
280
320
255
285
310
335
380
290
320
350
380
430
170
190
210
225
260
205
230
250
270
310
230
255
280
305
350
250
300
350
400
500
600
700
750
800
900
355
385
400
410
435
420
460
475
490
520
475
520
535
555
585
285
310
320
330
355
340
375
385
395
425
385
420
435
450
480
600
700
750
800
900
1000
1250
1500
1750
2000
455
495
520
545
560
545
590
625
650
665
615
665
705
735
750
375
405
435
455
470
445
485
520
545
560
500
545
585
615
630
1000
1250
1500
1750
2000
CorrectionFactors
Ambient
Temp °C For ambient temperatures otherthan 30°C (86°F), multiply the allowable ampacitiesshown
aboveby the appropriate factor shown below. Ambient
Temp °F
21-25
26-30
31-35
36-40
41-45
46-50
51-55
56-60
61-70
71-80
1.08
1.00
.91
.82
.71
.58
.41
.......
.......
.......
1.05
1.00
.94
.88
.82
.75
.67
.58
.33
.......
1.04
1.00
.96
.91
.87
.82
.76
.71
.58
.41
1.08
1.00
.91
.82
.71
.58
.41
.......
.......
.......
1.05
1.00
.94
.88
.82
.75
.67
.58
.33
.......
1.04
1.00
.96
.91
.87
.82
.76
.71
.58
.41
70-77
78-86
87-95
96-104
105-113
114-122
123-131
132-140
141-158
159-176
* Unless otherwise speci fically permitted elsewhe rei n this Code, the overcurrent prot ection for conductor types ma rked with an
asterisk (*) shall not exce ed 15 amperes for No. 14, 20 amper es for No. 12, and 30 amperes for No. 1 0 copper; or 15 amperes for
No.12and 25 amperes for No. 10aluminum and copper-cladaluminum after any correctionfactors for ambienttemperature and
numberof conductors have beenapplied.
1Reprintedwith permission fromNEC 1999, NFPA 70, the National ElectricalCode®, Copyright 1998, NationalFire Protection
Association, Quincy, M A 02269. This reprinted materi al is not the complete and officia lp osition of the National Fire Pro tection
Association, on the refe renced subject which is repres ented only by the standard in its en tirety.