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Wire Size
FIRE HAZARD To satisfy safety requirements, load wires must be large enough not to
overheat when carrying the maximum short-circuit output current. 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 unit. Paralleled load wires may be required for larger-ampacity
models.
The following table lists the characteristics of AWG (American Wire Gauge) copper wire.
AWG
18
16
14
12
10
8
6
4
2
Note 1 Ampacity is based on a single conductor in free air, 26-30 °C ambient temperature with the conductor rated at 60 °C. Ampacity
decreases at higher temperatures.
Note 2 Resistance is in ohms/1000 feet, at 20 °C wire temperature.
Along with ampacity, you must also consider voltage drop in the load lead due to wire resistance sizing
wires. The power supply will tolerate a voltage drop of 1 V per lead while maintaining the specified
programming accuracy, measurement accuracy, and load regulation (see specifications). Voltage
drops of up to 25% of the rated output voltage per lead will be tolerated - resulting in an additional 4
mV of voltage regulation for each additional volt dropped per load lead. Of course, any voltage drop in
the load leads reduces the maximum voltage available at the load. Subtract the load lead drop from
the rated output voltage to determine the maximum voltage available at the load.
Single Load Connections
1. As shown in the following figure, terminate all load wires with wire terminal lugs securely attached.
DO NOT use unterminated wires for load connections at the power supply.
2. Route the wires through the safety cover before attaching them to the bus bars. Knockouts are
provided on for larger diameter wires. The figure illustrates the recommended hardware for con-
necting wires to the bus bars. You must provide all cabling. Ensure that the wire-mounting hard-
ware does not short the output terminals.
Keysight RP7970 & RP7980 Series Operating and Service Guide
Equivalent mm 2
Nearest Metric size
1.0 mm 2
0.82
1.5 mm 2
1.31
2.5 mm 2
2.1
3.3
5.3
10 mm 2
8.4
16 mm 2
13.3
25 mm 2
21.2
35 mm 2
33.6
Ampacity (Note 1)
up to 14 A
up to 18 A
up to 25 A
4 mm 2
up to 30 A
6 mm 2
up to 40 A
up to 60 A
up to 80 A
up to 105 A
up to 140 A
2 Installing the Instrument
Resistance (Note 2)
6.385 Ω
4.016 Ω
2.525 Ω
1.588 Ω
0.999 Ω
0.628 Ω
0.395 Ω
0.248 Ω
0.156 Ω
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