Engineering

 Wire and Cable Ampacities**

Copper
Size AWG or kcmil
Aluminum
TW, NM-B,
UF (60°C)
RHW, THW, THWN, XHHW, USE (75°C)
RHH, THHN, THWN- 2, XHHW-2, SE, RHW-2, USE-2 (90°C)
TW, NM-B, UF
(60°C)
RHW, THW, THWN, XHHW, USE (75°C)
RHH, THHN, THWN-2, XHHW-2, SE, RHW-2, USE-2 (90°C)
15
15
15
14**
-
-
-
20
20
20
12**
15
15
15
30
30
30
10**
25
25
25
40
50
55
8
30
40
45
55
65
75
6
40
50
60
70
85
95
4
55
65
75
85
100
110
3
65
75
85
95
115
130
2
75
90
100
110
130
150
1
85
100
115
125
150
170
1/0
100
120
135
145
175
195
2/0
115
135
150
165
200
225
3/0
130
155
175
195
230
260
4/0
150
180
205
215
255
290
250
170
205
230
240
285
320
300
190
230
255
260
310
350
350
210
250
280
280
335
380
400
225
270
305
320
380
430
500
260
310
350
355
420
475
600
285
340
385
385
460
520
700
310
375
420
400
475
535
750
320
385
435
410
490
555
800
330
395
450
435
520
585
900
355
425
480
455
545
615
1000
375
445
500
       

* Ampacity is based upon the National Electrical Code® (NEC®), 2008, Table 310.16.  Allowable Ampacities of insulated conductors rated 0 through 2000 Volts, 60°C to 90°C (140°F to 194°F) and not more than three current-carrying conductors in raceway or cable or earth. Based on ambient temperature of 30°C (86°F).

**Small conductor (14-10 AWG) ampacities shown are per National Electrical Code® (NEC®) 240.4(D).

 

Single Conductors
 
Multiple Conductors
Cerrowire® single conductor types (excluding TFFN) are pulled through conduit for use in branch circuits, feeders, or service entrance conductors as specified in the NEC®. The voltage rating for all Cerrowire® single conductor type is 600V. Cerrowire® multiple conductor cables are recommended for use as specified in the NEC®. The voltage rating for all Cerrowire® single conductor type is 600V.
THHN
Type THHN or THWN - may be used in wet or dry locations at conductor temperatures not to exceed 90°C. If marked MTW it may be used as machine tool wiring at conductor temperatures not to exceed 60°C. AWM marking signifies appliance wiring material at conductor temperatures not to exceed 105°C. Sizes 1/0 and larger is suitable for use in cable trays. 
NM-B
Type NM-B is primarily used in residential wiring as branch circuits for outlets, switches, and other loads. NM-B may be used for both exposed and concealed work in dry locations at conductor temperatures not to exceed 90°C. Ampacity limited to 60°C for conductors.
USE
Type USE-2, RHH and RHW-2 can be used for underground service entrance, including direct burial. It may be used in wet or dry locations at conductor temperatures not to exceed 90°C. 
UF-B
Type UF-B may be used underground, including direct burial, for supplying power to outside lamp posts, well pumps, workshops, etc. May be used for interior branch circuit wiring in dry, wet, or corrosive locations at conductor temperatures not to exceed 90°C Ampacity limited to 60°C for conductors.
XHHW-2
Type XHHW-2 may be used in wet or dry locations where conductor temperatures do not exceed 90°C.  
SEU
Service Entrance Cable,Type SEU, is typically used in residential buildings to transfer power from the service drop to the panel box. Each phase conductor is type THHN or THWN which is suitable for use where conductor temperatures do not exceed 90°C.
TFFN
Type TFFN can be used as fixture wire where conductor temperatures do not exceed 90°C. It may also be used as MTW at conductor temperatures not to exceed 60°C or as AWM at 105°C. 
SER
Service Entrance Cable, Type SER, is normally used in multi-family residential housing to take power from meter base to panel box in an individual apartment. Each phase conductor is type THHN or THWN for use where conductor temperatures do not exceed 90°C.
 
  
Mobile Home Feeder
Mobile Home Feeder is used to connect a mobile home to an electrical supply where permanent wiring is required as specified in the NEC®. Each conductor is Type USE-2, RHH and RHW-2 which is suitable for direct burial at conductor temperatures not to exceed 90°C.