Juniper QFX10016, Hardware Manual

Page: 300 / 439

the battery plant, you can use a multimeter to verify the resistance of the –48V and RTN DC cables
to chassis ground:
• The cable with very high resistance (indicating an open circuit) to chassis ground is negative (–)
and will be installed on the –48V (input) DC power input terminal.
• The cable with very low resistance (indicating a closed circuit) to chassis ground is positive (+)
and will be installed on the RTN (return) DC power input terminal.
CAUTION: You must ensure that power connections maintain the proper polarity.
The power source cables might be labeled (+) and (–) to indicate their polarity.
There is no standard color coding for DC power cables.
10. Install each power cable lug on the DC power input terminal, securing it with the nut (see Figure
140 on page 290 ). Apply between 23 in.-lb (2.6 Nm) and 25 in.-lb (2.8 Nm) of torque to each nut.
(Use the 13/32 in. [10 mm] nut driver or socket wrench.)
a. Secure each positive (+) DC source power cable lug to the RTN (return) DC power input
terminal.
289