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M320 DC Power Cable Specifications


The accessory box shipped with the router includes the cable lugs that attach to the terminal studs of each power supply (see Figure 1). (The cable lug shown in is also used for the grounding the chassis.)

Figure 1: DC Power Cable Lug
DC Power Cable Lug

Before router installation begins, 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 router.

Table 1 summarizes the specifications for the power cables, which you must supply.

Table 1: DC Power Cable Specifications

Cable Type

Quantity and Specification

Connector Specification


Eight 4-AWG (21.2 mm2 ) (minimum) copper conductor, or as permitted by the local code.

Cable lug; dual hole, sized to fit 1/4-20 UNC terminal studs at 15.86-mm (0.625-in.) center line.


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.

Figure 2 shows a typical DC source cabling arrangement.

Figure 2: Typical DC Source Cabling to the Router
Typical DC Source Cabling
to the Router

For field-wiring connections, use copper conductors only.

For other electrical safety information, see M320 General Electrical Safety Guidelines and Electrical Codes, M320 DC Power Electrical Safety Guidelines, and DC Power Electrical Safety Warnings for Juniper Networks Devices.


Power cords and cables must not block access to router components or drape where people could trip on them.

For a description of the DC power supply, see , as opposed to the DC power configuration (see M320 DC Power Supplies Description for more information). For instructions on connecting the DC power and grounding cables during initial installation, see Connecting Power to a DC-Powered M320 Router. For instructions on replacing a DC power cable, see Replacing an M320 DC Power Supply Cable.