FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 5. Electical Wire Rating | 11-66. General
9/27/01
AC 43.13-1B CHG 1
Where:
T1 = Ambient Temperature
T2 = Estimated Conductor Temperature
TR = Conductor Temperature Rating
I2 = Circuit Current (A=Amps)
Imax = Maximum Allowable Current
(A=Amps) at TR
This formula is quite conservative and will typi
cally yield somewhat higher estimated tempera
tures than are likely to be encountered under actual
operating conditions.
Note: Aluminum wire-From Table 11-9 and
11-10 note that the conductor resistance of
aluminum wire and that of copper wire (two
numbers higher) are similar. Accordingly,
the electric wire current in Table 11-9 can
be used when it is desired to substitute alu-
minum wire and the proper size can be se-
lected by reducing the copper wire size by
two numbers and referring to Table 11-10.
The use of aluminum wire size smaller than
No. 8 is not recommended.
TABLE 11-9. Current carrying capacity and resistance of copper wire.
Wire
Size
Continuous duty current (amps)-Wires in bundles,
groups, harnesses, or conduits. (See Note #1)
Wire Conductor Temperature Rating
105 °C
150 °C
200 °C
Max. resistance
ohms/1000ft@20 °C
tin plated conduc
tor
(See Note #2)
Nominal
conductor
area
circ.mils
24
2.5
4
22
3
5
20
4
7
18
6
9
16
7
11
14
10
14
12
13
19
10
17
26
8
38
57
6
50
76
4
68
103
2
95
141
1
113
166
0
128
192
00
147
222
000
172
262
0000
204
310
5
28.40
475
6
16.20
755
9
9.88
1,216
12
6.23
1,900
14
4.81
2,426
18
3.06
3,831
25
2.02
5,874
32
1.26
9,354
71
0.70
16,983
97
0.44
26,818
133
0.28
42,615
179
0.18
66,500
210
0.15
81,700
243
0.12
104,500
285
0.09
133,000
335
0.07
166,500
395
0.06
210,900
Note #1: Rating is for 70°C ambient, 33 or more wires in the bundle for sizes 24 through 10, and 9
wires for size 8 and larger, with no more than 20 percent of harness current carrying capacity being used,
at an operating altitude of 60,000 feet. For rating of wires under other conditions or configurations see
paragraph 11-69.
Note #2: For resistance of silver or nickel-plated conductors see wire specifications.
Par 11-66
Page 11-23