Juniper EX4300 Series

NOTE: The power supply slots are at the right end of the rear panel on 24-port and 48-port
switches, and at the le end on 32-port switches. Figure 69 on page 204 shows how to
secure ring lugs to the terminals on the DC power supply installed on 24-port or 48-port
EX4300 switches. The procedure is the same for 32-port EX4300 switches.
2. Verify that the DC power cables are correctly labeled before making connecons to the power
supply. In a typical power distribuon scheme where the return is connected to chassis ground at
the baery plant, you can use a mulmeter to verify the resistance of the –48V and RTN DC cables
to chassis ground:
• The cable with very low resistance (indicang a closed circuit) to chassis ground is posive (+)
and will be installed on the V+ (return) DC power input terminal.
• The cable with very high resistance (indicang an open circuit) to chassis ground is negave (–)
and will be installed on the V– (input) DC power input terminal.
CAUTION: You must ensure that power connecons 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 aach to the DC power input terminals on each power
supply.
3. Install heat-shrink tubing insulaon around the power cables.
To install heat-shrink tubing:
a. Slide the tubing over the poron of the cable where it is aached to the lug barrel. Ensure that
tubing covers the end of the wire and the barrel of the lug aached 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 ghtly.
Figure 68 on page 202 shows the steps to install heat-shrink tubing.
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