| The use of this table for establishing ampacity ratings is an inexact procedure. This table should only be used as a starting point when establishing ratings for any given situation. Values may be lesser or greater than those given in the table because of the influence of installation method, environment, number of conductors, conductor composition and size, ambient temperatures, insulation types, etc. It is recommended that design engineers desiring accurate ampacity data closely study the 1990 National Electrical Code Handbook Article 310-15-310-84. Additional information can be derived from AIEE, paper number 57-660, “The calculation of the temperature rise and load capability of cable systems” by J. H. Neher and M. H. McGrath. This paper was presented to the AIEE general meeting in Montreal, Quebec, Canada on June 24-28,1956 and was published in the “AIEE transactions,” part 3 (power apparatus and systems), Volume 76, October, 1957, pp. 752-772. |
|
Conductor Types:
tc = tinned copper
npc = nickel plated copper
npi = nickel plated iron
A-nickel = Type ‘A” 100% nickel
Current Carrying Capacity Base Temperature at 40°C (Values tabulated are In Amperes)
| Wire Gage AWG | Conductor Type | |||||
| 200°C | 250°C | 250°C | 250°C | 450°C | 450°C | |
| tc,npc | npc-7% | A-nickel | npi | npc-27% | A-nickel | |
|
24
|
7.2
|
8.0
|
4.0
|
3.3
|
9.0
|
4.3
|
|
22
|
9.6
|
10.8
|
5.0
|
4.4
|
12.0
|
5.6
|
|
20
|
14.0
|
15.0
|
7.0
|
6.0
|
18.0
|
8.0
|
|
18
|
18.0
|
20.0
|
9.4
|
8.0
|
23.0
|
11.0
|
|
16
|
24.0
|
26.0
|
12.0
|
11.0
|
30.0
|
14.0
|
|
14
|
36.0
|
39.0
|
18.0
|
16.0
|
45.0
|
21.0
|
|
12
|
45.0
|
49.0
|
23.0
|
20.0
|
56.0
|
26.0
|
|
10
|
60.0
|
66.0
|
31.0
|
27.0
|
75.0
|
35.0
|
|
8
|
83.0
|
91.0
|
-
|
-
|
104.0
|
49.0
|
|
6
|
110.0
|
121.0
|
-
|
-
|
138.0
|
65.0
|
Temperature Correction Factors For ambient temperatures other than 40°C (104°F), multiply the ampacities shown above by the appropriate factor shown below
| Ambient | Temperature | Wire Temperature Rating | ||
| °C | °F | 200°C | 250°C | 450°C |
|
41-50
|
106-122
|
0.97
|
0.98
|
0.99
|
|
51-60
|
124-140
|
0.94
|
0.95
|
0.99
|
|
61-70
|
142-158
|
0.90
|
0.93
|
0.96
|
|
71-80
|
160-176
|
0.87
|
0.90
|
0.95
|
|
81-90
|
177-194
|
0.83
|
0.87
|
0.90
|
|
91-100
|
195-212
|
0.72
|
0.85
|
0.92
|
|
101-120
|
213-248
|
0.71
|
0.79
|
0.89
|
|
121-140
|
249-284
|
0.61
|
0.71
|
0.86
|
|
141-160
|
285-320
|
0.50
|
0.65
|
0.84
|
|
161-180
|
321-356
|
0.35
|
0.58
|
0.81
|
|
181-200
|
357-392
|
-
|
0.49
|
0.78
|
|
201-225
|
393-437
|
-
|
0.35
|
0.74
|
|
226-250
|
439-482
|
-
|
-
|
0.69
|
|
251-275
|
483-527
|
-
|
-
|
0.65
|
|
276-300
|
528-572
|
-
|
-
|
0.60
|
|
301-325
|
573-617
|
-
|
-
|
0.55
|
|
326-350
|
618-662
|
-
|
-
|
0.49
|
|
351-375
|
663-707
|
-
|
-
|
0.42
|
|
376-400
|
708-752
|
-
|
-
|
0.34
|
Copyright 2003,
NEWPORT Electronics, Inc. All rights reserved.