Connecting Earth Ground to a QFX3008-I Interconnect Device

To meet safety and electromagnetic interference (EMI) requirements and to ensure proper operation, we recommend that the QFX3008-I Interconnect device be adequately grounded before it is connected to power.

Two pairs of threaded inserts (PEM nuts) are provided on the QFX3008-I Interconnect device for connecting the device to earth ground. The first pair is sized for M6 screws and is located below the wiring tray on the bottom left corner at the rear of the chassis. The second pair is sized for UNC ¼-20 screws and is located below the second wiring tray on the bottom right corner at the rear of the chassis. The grounding points are spaced 0.625 in. (15.86 mm) apart. The grounding lug required is a Panduit LCD2-14A-Q or equivalent.

The accessory box shipped with the device includes a cable lug and two UNC ¼-20 screws with integrated washers. For power cord and grounding cable specifications, see AC Power Cord Specifications for a QFX3008-I Interconnect Device with Single-Phase Wiring Trays, AC Power Cord Specifications for a QFX3008-I Interconnect Device with Three-Phase Delta Wiring Trays, AC Power Cord Specifications for a QFX3008-I Interconnect Device with Three-Phase Wye Wiring Trays, and Grounding Cable and Lug Specifications for a QFX3008-I Interconnect Device.

Before you begin to connect the QFX3008-I Interconnect device to earth ground:

• Ensure that you understand how to prevent ESD damage. See Prevention of Electrostatic Discharge Damage.
• Ensure that a licensed electrician has attached the grounding lug to an appropriate grounding cable (see Grounding Cable and Lug Specifications for a QFX3008-I Interconnect Device).

  Caution: Using a grounding cable with an incorrectly attached lug can damage the device.

Ensure you have the following tools and parts available to connect a QFX3008-I Interconnect device to earth ground:

• Electrostatic discharge (ESD) grounding strap
• Grounding cable (not provided) with attached lug
• Screws and split washers to secure the grounding lug to the protective earthing terminal (two UNC ¼-20 screws with integrated washers are provided)
• Phillips (+) torque screwdriver, number 2

  Caution: You must use an appropriate torque-controlled tool to tighten the screws on the grounding lug. Applying excessive torque damages the grounding lug or chassis. Ground lugs should be installed with SAE Grade 5 screws or better at no more than 72 in-lb (8 Nm).

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to the approved ESD site grounding point.
2. Connect one end of the grounding cable to a proper earth ground, such as the rack in which the device is installed.
3. Detach the ESD grounding strap from the site ESD grounding point.
4. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to the ESD point on the chassis.
5. In a four-post rack, place the grounding lug attached to the grounding cable over one of the rear support anchors, as shown in Figure 1.

   In a two-post rack, place the grounding cable lug over the grounding points on the bottom rear of the chassis below the wiring trays.

   The left pair is sized for M6 screws, and the right pair is sized for UNC ¼-20 screws.

6. Using the torque screwdriver, secure the grounding lug to the protective earthing terminal.

Figure 1: Connecting a Grounding Cable to a QFX3008-I Interconnect Device