iL Series User Manual
12
Rev B
California Instruments
2.7.3 Wire Considerations
Current Ratings
Fire Hazard:
To satisfy safety requirements, load wires must be large
enough not to overheat when carrying the maximum short-
circuit current of the AC source. If there is more than one load,
then any pair of load wires must be capable of safely carrying
the full-rated current of the AC source.
Table 6 lists the characteristics of AWG (American Wire Gage) copper wire.
Stranded Copper Wire Capacity and Resistance
AWG No.
Ampacity Resistance
(
Ω
Ω
/m)
AWG No.
Ampacity Resistance
(
Ω
Ω
/m)
14
25
0.0103
6
80
0.0016
12
30
0.0065
4
105
0.0010
10
40
0.0041
2
140
0.00064
8
60
0.0025
1/0
195
0.00040
Table 6 : American Wire Gage (AWG) characteristics
NOTES:
1. Ampacity is based on 30 ºC ambient temperature with conductor rated at 60 ºC.
For ambient temperature other than 30 ºC, multiply the above ampacities by the
following constants:
Temp (ºC)
Constant
Temp (ºC)
Constant
21 to 25
1.08
41 to 45
0.71
26 to 30
1.00
46 to 50
0.58
31 to 35
0.91
51 to 55
0.41
36 to 40
0.82
Table 7 : AWG temperature coefficients
2. Resistance is nominal at 75 ºC wire temperature.
Voltage Drops
The load wires must also be large enough to avoid excessive voltage drops due to
the impedance of the wires. In general, if the wires are heavy enough to carry the
maximum short circuit current without overheating, excessive voltage drops will not
be a problem. The voltage drops across the load wires should be limited to less than
2% of the output voltage.
Refer to Table 6 if you need to calculate the voltage drop for some commonly used
AWG copper wire.
Summary of Contents for 3000iL
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