Flexible Cord Ampacities

The following data is taken from the 1981 National Electrical Code. Newer versions of the code exist, but the numbers should be pretty much the same. These ratings apply to thermoset types of insulation like SJ, SJO, SV, SVO, as well as thermoplastic types like SVT, and so forth. They are also based on an ambient temperature of 30C (86F), and would be derated for higher ambient temperatures.

Size (AWG)
"Column A"
3 current carrying conductors
"Column B"
2 current carrying conductors
18
7
10
16
10
13
14
15
18
12
20
25
10
25
30
8
35
40
6
45
55
4
60
70
2
80
95

 

There are two columns, A and B: A is for 3 or more conductor cords where all three conductors are current carrying (i.e. 3 phase power). B is for 2 or more conductor cords where only 2 conductors are current carrying (i.e. usual single phase case). If the number of current carrying conductors is greater than 3, derate according to the following table:

Number of Conductors
Percentage of value in table above
4 to 6
80
7 to 24
70
25 to 42
60
42 and above
50

Copyright 1998, Jim Lux / cordamp.htm / 20 September 1999 / Back to HV Home / Back to home page / Mail to Jim