Juniper EX9214 Hardware Manual page 192

3. On the power supply, rotate the metal cover away from the input mode switch to expose the
switch.
4. Move the input mode switch to position 0 for one feed or position 1 for two feeds.
NOTE: For a fully redundant configuration in two-feed mode, sixteen feeds are required.
5. Set the power switch of the power supply to the OFF (0) position.
6. Verify that the power cables are labeled before making connections to the power supply. In a
typical power distribution scheme where the return (RTN) is connected to chassis ground at the
battery plant, you can use a multimeter to verify the resistance of the –48 V and RTN DC cables to
chassis ground.
• Cable with large resistance (indicating an open circuit) to chassis ground is –48 V.
• Cable with low resistance (indicating a closed circuit) to chassis ground is RTN.
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. The color coding used by
the external DC power source at your site determines the color coding for the leads
on the power cables that attach to the terminal studs on each power supply.
7. Install heat-shrink tubing insulation around the power cables.
To install heat-shrink tubing:
a. Slide the tubing over the portion of the cable where it is attached to the lug barrel. Ensure that
tubing covers the end of the wire and the barrel of the lug attached to it.
b. Shrink the tubing with a heat gun. Ensure that you heat all sides of the tubing evenly so that it
shrinks around the cable tightly.
Figure 54 on page 182 shows the steps to install heat-shrink tubing.
181