COPPER WIRE CURRENT CAPACITY
Single wire in open air, ambient temperature 86oF

Ampacities of Wire Types (w/ Temp Rating) @ 0-2000 Volts

Wire
Size
AWG
TW
UF
(140oF)
FEPW, RH, RHW, THW, THWN, ZW,
THHW, XHHW
(167oF)

USE-2, XHH, XHHW, -2, TA, TBS, SA, SIS, FEP
MI, RHW-2, THHN, ZW-2,
THWN-2, FEPB, RHH,
THHW, THW-2    
                (194oF)

0000
000
00
0
1
2
3
4
6
8
10
12
14
16
20
300
260
225
195
165
140
120
105
80
60
40
30
25
- -
- -
360
310
265
230
195
170
145
125
95
70
50
35
30
- -
- -
405
350
300
260
220
190
165
140
105
80
55
40
35
24
18
Note:  Type TW is the most common for house wiring.  TW is for dry or wet conditions and is covered in a single layer of plastic. 

If the ambient temperature( 1 ) is over 86oF (30oC), then the following corrections should be made by multiplying the above ampacities by the correction factor below.

Ambient( 1 ) Ampacity Correction for above Wire types

Temp oF 140 oF 167 oF 194 oF
96-104
105-113
114-122
123-131
132-140
141-158
159-176
0.82
0.71
0.58
0.41
- - -
- - -
- - -
0.88
0.82
0.75
0.67
0.58
0.35
- - -
0.91
0.87
0.82
0.76
0.71
0.58
0.41
( 1 ) Ambient Temperature is the temperature of the material (air, earth, etc.) surrounding the wire. 

COPPER WIRE CURRENT CAPACITY
Three wires in cable, ambient temperature 86oF

Ampacities of Wire Types (w/ Temp Rating) @ 0-2000 Volts

Wire
Size
AWG
TW
UF
(140oF)
FEPW, RH, RHW
THHW, ZW, THWN
XHHW, THW, USE
(167oF)
   USE-2, XHH,XHHW,-2
   TA, TBS, SA, SIS, FEP
   MI, RHW-2, THHN, ZW-2
   THWN-2, FEPB, RHH
   THHW, THW-2
                 (194oF)
0000
000
00
0
1
2
3
4
6
8
10
12
14
16
18
195
165
145
125
110
95
85
70
55
40
30
25
20
- -
- -
230
200
175
150
130
115
100
85
65
50
35
25
20
- -
- -
260
225
195
170
150
130
110
95
75
55
40
30
25
18
14
Note:  All notes that apply to single wire ambient temperature, apply also to this Three Wire section.

Note:  The information on this page has been taken from the National Electrical Code ®, National Fire Protection Association, Quincy, Massachusetts  02269, Copyright 1993 and does not represent the complete code.

Note:  In all Copper Wire Types listed above (except types: MI, TA, TBS, SA, SIS, RHW-2, THW-2, THWN-2, USE-2, XHH, XHHW-2, & ZW-2) overcurrent protection should not exceed 15 amps for 14 AWG,
20 amps for 12 AWG, and 30 amps for 10 AWG.  This is not true if specifically permitted elsewhere in the Code.