Connecting the EX9208 to Power
Connect Earth Ground to an EX Series Switch
To ensure proper operation and to meet safety and electromagnetic interference (EMI) requirements, you must connect an EX Series switch to earth ground before you connect power to the switch. You must use the protective earthing terminal on the switch chassis to connect the switch to earth ground (see Figure 2).
You must install the EX Series switch in a restricted–access location and ensure that the chassis is always properly grounded. EX Series switches have a two–hole protective grounding terminal provided on the chassis. See Table 1 for the location of the earthing terminals on various EX Series switches. We recommend that you use the protective grounding terminal as the preferred method for grounding the chassis regardless of the power supply configuration. However, if additional grounding methods are available, you can also use those methods. For example, you can use the grounding wire in the power cord of an AC power supply or use the grounding terminal or lug on a DC power supply. This system was tested to meet or exceed all applicable EMC regulatory requirements with the two-hole protective grounding terminal connected correctly.
Ensure that a licensed electrician has attached an appropriate grounding lug to the grounding cable you supply. Using a grounding cable with an incorrectly attached lug can damage the switch.
Parts and Tools Required for Connecting an EX Series Switch to Earth Ground
Special Instructions to Follow Before Connecting Earth Ground to an EX Series Switch
Parts and Tools Required for Connecting an EX Series Switch to Earth Ground
Before you begin connecting an EX Series switch to earth ground, ensure you have the parts and tools required for your switch.
Table 1 lists the earthing terminal location, grounding cable and lug specifications, and parts needed for connecting an EX Series switch to earth ground.
Table 1: Parts Required for Connecting an EX Series Switch to Earth Ground
Switch | Earthing Terminal Location | Grounding Cable Requirements | Grounding Lug Specifications | Screws and Washers | Additional Information |
---|---|---|---|---|---|
EX2200 | Rear panel of the chassis | 14 AWG (2 mm²), minimum 90° C wire, or as permitted by the local code | Panduit LCC10-14BWL or equivalent— |
| |
EX2300-C | Rear panel of the chassis | 14 AWG (2 mm²), minimum 90° C wire, or as permitted by the local code | Panduit LCC10-14AW-L or equivalent— |
| |
EX2300 | Rear panel of the chassis |
|
|
| |
EX3200, EX3300, and EX3400 | Rear panel of the chassis | 14 AWG (2 mm²), minimum 90° C wire, or as permitted by the local code | Panduit LCC10-14BWL or equivalent— |
| For EX3200 Switches See Special Instructions to Follow Before Connecting Earth Ground to an EX Series Switch. |
EX4200, EX4500, and EX4550 | Left side of the chassis | 14 AWG (2 mm²), minimum 90° C wire, or as permitted by the local code | Panduit LCC10-14BWL or equivalent— |
| See Special Instructions to Follow Before Connecting Earth Ground to an EX Series Switch. |
EX6210 | Rear panel of the chassis (on lower left side) | The grounding cable must be the same gauge as the power feed cables and as permitted by the local code. | Panduit LCD2-14A-Q or equivalent |
| |
EX8208 | Left side of the chassis | 6 AWG (13.3 mm²), minimum 90° C wire, or as permitted by the local code | Panduit LCD2-14A-Q or equivalent |
| |
EX8216 | Two earthing terminals:
Note: You must use only one of the two protective earthing terminals. | 2 AWG (33.6 mm²), minimum 90° C wire, or as permitted by the local code | Panduit LCD2-14A-Q or equivalent |
| |
EX9204, EX9208, and EX9214 | Rear panel of the chassis | One 6 AWG (13.3 mm²), minimum 90° C wire, or one that complies with the local code | Thomas& Betts LCN6-14 or equivalent— |
| See Grounding Cable and Lug Specifications for EX9200 Switches. |
EX9251 | Rear panel of the chassis | 12 AWG (2.5 mm²), minimum 90° C wire,
or one that complies with the local code— | Panduit LCD10-10A-L or equivalent— | Two 10-32 screws— | See Grounding Cable and Lug Specifications for EX9200 Switches. |
EX9253 | Right side of the chassis | 14-10 AWG (2-5.3 mm²), minimum 90° C wire,
or one that complies with the local code— | Panduit LCD10-14B-L or equivalent— | Two M5 Pan Head screws— |
Tools required for connecting an EX Series switch to earth ground:
An electrostatic discharge grounding strap (provided)
A Phillips (+) number 2 screwdriver to tighten the screws.
An AC–powered EX Series switch gains additional grounding when you plug the power supply in the switch into a grounded AC power outlet by using an AC power cord appropriate for your geographical location.
Special Instructions to Follow Before Connecting Earth Ground to an EX Series Switch
Table 2 lists the special instructions that you might need to follow before connecting earth ground to a switch.
Table 2: Special Instructions to Follow Before Connecting Earth Ground to an EX Series Switch
Switch | Special Instructions | ||||
---|---|---|---|---|---|
EX3200 and EX4200 | Some early variants of EX3200 and EX4200 switches for which the Juniper Networks model number on the label next to the protective earthing terminal is from 750-021xxx through 750-030xxx require 10-24x.25 in. screws. | ||||
EX4200, EX4500, and EX4550 | If you plan to mount your switch on four posts of a rack or cabinet, mount your switch in the rack or cabinet before attaching the grounding lug to the switch. Note: The protective earthing terminal on switches mounted on four posts of a rack is accessible through the slot on the left rear bracket only if the rack is 27.5 in. (69.85 cm) through 30.5 in. (77.47 cm) deep for a switch mounted flush with the rack front and 29.5 in. (74.93 cm) through 32.5 in. (82.55 cm) deep for a switch mounted 2 in. (5.08 cm) recessed from the rack front. See Figure 1. ![]()
Note: The brackets must be attached to the chassis before the grounding lug is attached. (The brackets are shown pulled away from the chassis so that the protective earthing terminal is seen.) |
Connecting Earth Ground to an EX Series Switch
To connect earth ground to an EX Series switch:
- Verify that a licensed electrician has attached the cable lug to the grounding cable.
- Connect one end of the grounding cable to a proper earth ground, such as the rack in which the switch is mounted.
- Attach an ESD grounding strap to your bare wrist, and connect the strap to the ESD grounding point on the switch.
- Place the grounding lug attached to the grounding cable
over the protective earthing terminal. See Figure 2.
Figure 2: Connecting a Grounding Cable to an EX Series Switch - Secure the grounding lug to the protective earthing terminal with the washers and screws.
- Dress the grounding cable and ensure that it does not touch or block access to other switch components and that it does not drape where people could trip over it.
Connecting AC Power to an EX9208 Switch
EX9208 switches can be configured with up to four AC power supplies.
Mixing AC and DC power supplies in the same chassis is not supported.
Each power supply must be connected to a dedicated AC power source outlet.
Before you begin to connect power to the switch:
Ensure you understand how to prevent electrostatic discharge (ESD) damage. See Prevention of Electrostatic Discharge Damage.
Ensure that you have connected the device chassis to earth ground, if required by your site guidelines or installation. A ground connection to the protective earthing terminal is not required for an AC-powered switch. The AC power cords provide adequate grounding when you connect the power supply in the switch to a grounded AC power outlet by using the AC power cord appropriate for your geographical location (see AC Power Cord Specifications for an EX9208 Switch).
Caution For installations that require a separate grounding conductor to the chassis, have a licensed electrician complete this connection before you connect the switch to power. For instructions on connecting earth ground, see Connect Earth Ground to an EX Series Switch.
Install power supplies in the switch. See Installing an AC Power Supply in an EX9208 Switch.
Ensure that you have the following parts and tools available to connect power to the switch:
ESD grounding strap (provided)
Power cords appropriate for your geographical location (not provided)
Ensure that the power cords do not block access to switch components or drape where people can trip on them.
To connect AC power to an EX9208 switch (see Figure 3):
- Attach the ESD grounding strap to your bare wrist, and connect the strap to the ESD point on the chassis.
- Ensure that the power supply is fully inserted and latched securely in the chassis. See Installing an AC Power Supply in an EX9208 Switch.
- If needed, move the AC input switch next to the appliance
inlet on the power supply faceplate, to the off (
O
) position. - Insert the coupler end of the power cord into the AC appliance inlet on the AC power supply faceplate.
- If the AC power source outlet has a power switch, set
it to the off (
O
) position. - Insert the power cord plug into an AC power source outlet.
- If the AC power source outlet has a power switch, set
it to the on (
|
) position. - Move the AC input switch next to the appliance inlet on
the power supply to the on
( | )
position and observe the status LEDs on the power supply faceplate. If the power supply is correctly installed and functioning normally, theAC OK
andDC OK
LEDs glow steady green, and thePS FAIL
LED is not lit. - Repeat steps 2 through 9 for the remaining power supplies.

Powering On an AC-Powered EX9200 Switch
Before you power on the switch, ensure that:
You have installed all required switch components.
You have installed the required number of power supplies to support redundant operation for the switch configuration.
You understand how to protect the switch from electrostatic discharge (ESD) damage . See Prevention of Electrostatic Discharge Damage.
Ensure that you have the following parts and tools available:
An ESD wrist strap
An external management device such as a PC
A cable to connect the external management device to the
CONSOLE
port or the Ethernet management<...>
port on the primary Routing Engine module (RE module).For connecting a management device to the console port, see Connecting an EX9200 Switch to a Management Console or an Auxiliary Device. For connecting a management device to the Ethernet management port, see Connecting an EX9200 Switch to a Network for Out-of-Band Management.
To power on the switch:
- Wrap and fasten one end of the ESD wrist strap around your bare wrist, and connect the other end of the strap to the ESD point on the switch.
- Connect the external management device to the Ethernet
management (
<...>
) port on the primary RE module. - Turn on the power to the external management device.
- Ensure that the power supplies are fully inserted in the chassis and that each of their handles is flush against the faceplate.
- Ensure that the source power cord is inserted securely into the appliance inlet for each AC power supply.
- Switch on the dedicated customer site circuit breakers for the power supplies. Follow the ESD and safety instructions for your site.
- Flip the AC input switch on the power supply to the On
(
|
) position. Observe the power supply faceplate LEDs. If the power supply is installed correctly and functioning normally, theAC OK
andDC OK
LEDs glow steady green. ThePS FAIL
LED does not glow. - Repeat Step 7 for the remaining power supplies installed
in the switch.
If any of the status LEDs indicates that the power supply is not functioning normally, repeat the installation and cabling procedures. See Connecting AC Power to an EX9204 Switch, Connecting AC Power to an EX9208 Switch, or Connecting AC Power to an EX9214 Switch.
- On the external management device, monitor the startup process to ensure that the system boots properly.
After you power on a power supply, wait for at least 60 seconds before you turn it off. After you power off a power supply, wait for at least 60 seconds before you turn it back on.
If the system is completely powered off when you switch on a power supply, the RE module boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power off the system again, first issue the CLI request system halt command.
After you power on a power supply, it can take up to 60 seconds for status indicators such as power supply LEDs and the show chassis operational mode CLI command display to indicate that the power supply is functioning normally. Ignore any error indicators that might appear during the first 60 seconds.
Connecting DC Power to an EX9208 Switch
An EX9208 switch can be configured with up to four DC power supplies.
Before performing DC power procedures, ensure that
power is removed from the DC circuit. To ensure that all power is
off, locate the circuit breaker on the panel board that services the
DC circuit, switch the circuit breaker to the OFF
position, and tape the switch handle of the circuit breaker in the OFF
position.
Before you connect power to the switch, a licensed electrician must attach a cable lug to the grounding and power cables that you supply. A cable with an incorrectly attached lug can damage the switch (for example, by causing a short circuit).
Mixing AC and DC power supplies in the same chassis is not a supported configuration.
Each power supply input feed must be connected to a dedicated DC power source outlet.
Before you begin connecting DC power to an EX9208 switch:
Ensure that you have taken the necessary precautions to prevent electrostatic discharge (ESD) damage (see Prevention of Electrostatic Discharge Damage).
Ensure that you have connected the switch chassis to earth ground.
Caution To meet safety and electromagnetic interference (EMI) requirements and to ensure proper operation, you must connect EX9208 switches to earth ground before you connect them to power. For installations that require a separate grounding conductor to the chassis, use the protective earthing terminal on the switch chassis to connect to earth ground. For instructions on connecting an EX9208 switch to ground using a separate grounding conductor, see Connect Earth Ground to an EX Series Switch.
Install the power supply in the chassis. See Installing a DC Power Supply in an EX9208 Switch.
Ensure that you have the following parts and tools available to connect DC power to an EX9208 switch:
ESD grounding strap
DC power source cables (not provided) with the cable lugs (provided) attached.
The provided cable lugs in an EX9208 switch are sized for 6 AWG (13.3 mm2) power source cables. The DC power source cables that you provide must be 6 AWG (13.3 mm2), minimum 60°C wire. We recommend that you install heat-shrink tubing insulation around the power cables and lugs.
3/8-in. (9.5-mm) nut driver or socket wrench
Phillips (+) screwdriver, number 1 and 2
Multimeter
Ensure that the power cords do not block access to switch components or drape where people can trip on them.
To connect DC power to an EX9208 switch:
- Switch off the dedicated customer site circuit breakers. Ensure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cable leads might become active during installation.
- Attach the ESD grounding strap to your bare wrist, and connect the strap to the ESD point on the chassis.
- Move the power switch on the power supply faceplate to
the off (
O
) position. - Using a screwdriver, loosen the captive screw holding the metal cover over the DIP input mode switch. Remove the metal cover from the DIP input mode switch to expose the switch.
- Check the setting of the DIP input mode switch. Use a
sharp, nonconductive object to slide the switch to the desired position.
Set the input mode switch to position
0
for 60 A input and position1
for 70 A input (see Figure 4). This setting is used by the power management software and needs to be set before you switch on the power supply.Figure 4: DIP Input Mode Switch - Install the metal cover over the DIP input mode switch, and use a screwdriver to tighten the captive screw.
- Remove the plastic cable cover from the DC power input terminals.
- Verify that the DC power cables are correctly labeled
before making connections to the power supply. In a typical power
distribution scheme where the return is connected to chassis ground
at the battery plant, you can use a multimeter to verify the resistance
of the
–48V
andRTN
DC cables to chassis ground:The cable with very large resistance (indicating an open circuit) to chassis ground is
–48V
.The cable with very 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.
- Remove the washers and nuts from each DC power input terminal, using a 7/16-in. [11-mm] nut driver or socket wrench.
- Secure each power cable lug to the terminal studs, first
with the flat washer, then with the split washer, and then with the
nut (see Figure 5).
Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm)
of torque to each nut. Do not overtighten the nut. (Use a 7/16-in.
[11-mm] torque-controlled driver or socket wrench.)
Secure the positive (+) DC source power cable lug to the
RTN
(return) terminal.Secure the negative (–) DC source power cable lug to the
–48V
(input) terminal.
Caution Ensure that each power cable lug seats flush against the surface of the terminal block as you are tightening the nuts. Ensure that each nut is properly threaded onto the terminal stud. You must be able to spin the nut freely with your fingers when it is first placed onto the terminal stud. Applying installation torque to the nut when improperly threaded may result in damage to the terminal stud.
Caution The maximum torque rating of the terminal studs on the DC power supply is 36 lb-in. (4.0 Nm). The terminal studs may be damaged if excessive torque is applied. Use only a torque-controlled driver or socket wrench to tighten nuts on the DC power supply terminal studs.
Caution The DC power supplies in
PEM0
andPEM1
must be powered by dedicated power feeds derived from feedA
, and the DC power supplies inPEM2
andPEM3
must be powered by dedicated power feeds derived from feedB
. This configuration provides the commonly deployedA/B
feed redundancy for the system.For information about connecting to DC power sources, see DC Power Supply Specifications for EX9208 Switches.
- Route the power cables along the cable restraint toward the left or right corner of the chassis. If needed, thread plastic cable ties, which you must provide, through the openings on the cable restraint to hold the power cables in place.
- Replace the clear plastic cover over the terminal studs on the faceplate.
- Verify that the power cabling is correct, that the cables are not touching or blocking access to switch components, and that they do not drape where people could trip on them.
- Switch on the dedicated customer site circuit breakers.
Follow your site's procedures for safety and ESD.
Verify that the
INPUT OK
LED on the power supply glows green. - On each of the DC power supplies, switch the DC circuit
breaker to the center position before moving it to the on (
|
) position.Note The circuit breaker may bounce back to the off (
O
) position if you move the breaker too quickly.Observe the status LEDs on the power supply faceplate. If the power supply is correctly installed and functioning normally, the
PWR OK
,BRKR ON
, andINPUT OK
LEDs glow steady green. - Repeat Steps 2 through 15 for the remaining power supplies.
A Switch Fabric module must be installed for the PWR OK
LED to function.

Powering On a DC-Powered EX9200 Switch
Before you power on the switch, ensure that:
You have installed all required switch components.
You have installed the required number of power supplies to support redundant operation for the switch configuration.
Ensure you understand how to prevent electrostatic discharge (ESD) damage. See Prevention of Electrostatic Discharge Damage.
Ensure that you have the following parts and tools available:
An ESD wrist strap
An external management device such as a PC
A cable to connect the external management device to the console (
CONSOLE
) port or the Ethernet management (<...>
) port on the primary Routing Engine module (RE module).For connecting a management device to the console port, see Connecting an EX9200 Switch to a Management Console or an Auxiliary Device. For connecting a management device to the management port, see Connecting an EX9200 Switch to a Network for Out-of-Band Management.
To power on the switch:
- Connect the external management device to the primary
RE module's Ethernet management (
<...>
) port. - Turn on the power to the external management device.
- Wrap and fasten one end of the ESD wrist strap around your bare wrist, and connect the other end of the strap to the ESD point on the switch.
- Verify that the power supplies are fully inserted in the chassis and that each of their handles is flush against the faceplate.
- Verify that the source power cables are connected to the
appropriate terminal: the positive (+) source cable to the return
terminal (labeled
RTN
) and the negative (–) source cable to the input terminal (labeled–48V
). - Switch on the dedicated customer site circuit breakers to provide power to the DC power cables.
- Check the
INPUT OK
LED is lit steadily green to verify that power is present. - If power is not present:
Verify that the fuse is installed correctly and turn on the breaker at the battery distribution fuse board or fuse bay.
Check the voltage with a meter at the terminals of the power supply for correct voltage level and polarity.
- On each of the DC power supplies, switch the DC circuit
breaker to the center position before moving it to the On (
—
) position.Note The circuit breaker might bounce back to the Off
O
) position if you move the breaker too quickly.If any of the status LEDs indicates that the power supply is not functioning normally, repeat the installation and cabling procedures. See Connecting DC Power to an EX9204 Switch, Connecting DC Power to an EX9208 Switch, or Connecting DC Power to an EX9214 Switch.
- Verify that the
BREAKER ON
LED glows steady green. - Verify that the
PWR OK
LED glows steady green, indicating the power supply is correctly installed and functioning normally.If the power supply is not functioning normally, repeat the installation and cabling procedures.
Note After powering off a power supply, wait for at least 60 seconds before turning it back on. After powering on a power supply, wait for at least 60 seconds before turning it off.
If the system is completely powered off when you power on the power supply, the Routing Engine boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power off the system again, first issue the CLI request system halt command.
After a power supply is powered on, it can take up to 60 seconds for status indicators—such as the status LEDs on the power supply and the show chassis command display—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds.
- On the external management device connected to the Routing Engine, monitor the startup process to verify that the system has booted properly.