Cisco Systems WSUPOE12VPSPL, 4500 E-Series manual Preventing Electrostatic Discharge Damage

Chapter 2 Preparing for Installation

Electrostatic Discharge

Note See the Site-Planning Checklist at the end of this chapter to help ensure that you complete all site-planning activities before you install the switch.

Electrostatic Discharge

Electrostatic discharge is common on Category 5E and Category 6 cabling systems.

Category 5E and Category 6 cables have higher capacitance than Category 5 cables. As a result, Category 5E and Category 6 cables can store higher voltages than Category 5 cables and are more prone to damaging networking equipment if a differential discharge event occurs.

Unshielded twisted-pair cables can store high voltages. When these charged cables are connected to networking equipment, energy is discharged into the networking equipment; this is known as electrostatic discharge (ESD). Networking equipment is commonly designed and tested to withstand common mode ESD events of up to 2000 V. The design for the common mode event is based on the expectation that the discharge is delivered to all pins of a port at once. Sometimes, voltage is discharged to some of the pins of the connector and not others, or to some pins on the connector before others. This is known as a differential discharge event, which can damage the networking equipment being connected.

You can take the following measures to prevent ESD cable damage:

•Ground the cable before connecting the networking equipment. You can create a grounding cable using an RJ-45 patch cable by doing the following:

–Bare the wires on one end

–Connect the wires to a suitable and safe earth ground

–Connect the RJ-45 cable to a female RJ-45 connector

•Briefly connect all cables to the grounded cable before connecting to networking equipment.

•Leave cables from the networking equipment in the distribution closet connected to ports at user desktops. After you make connections on either side of the cable to networking equipment, the cable will not build up charge.

Preventing Electrostatic Discharge Damage

Electrostatic discharge (ESD) damage, which can occur when electronic cards or components are improperly handled, results in complete or intermittent failures. Port adapters and processor modules consist of printed circuit boards that are fixed in metal carriers. Electromagnetic interference (EMI) shielding and connectors are integral components of the carrier. Although the metal carrier helps to protect the board from ESD, use a preventive antistatic strap during handling.

Following are guidelines for preventing ESD damage:

•Always use an ESD wrist or ankle strap and ensure that it makes good skin contact.

•Connect the equipment end of the strap to an unfinished chassis surface.

•When installing a component, use any available ejector levers or captive installation screws to properly seat the bus connectors in the backplane or midplane. These devices prevent accidental removal, provide proper grounding for the system, and help to ensure that bus connectors are properly seated.

Catalyst 4500 E-Series Switches Installation Guide

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