3Com 3C13701 Installation Manual

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3Com 3C13701 Installation Manual Manual pdf 23 page image

Connecting the PGND Wire 23Connecting thePGND Wire WARNING: The normal connection of the PGND wire is an important guard againstlightning and interference. Therefore, you must correctly connect the PGND wire beforeinstalling and using the device.The power input end of 3Com 5000 Routers is connected to a noise filter. The neutralpoint of the noise filter is directly connected to the chassis and is called protectionground (PGND). The PGND wire must be well grounded, so as to safely conduct thefaradism and leaky electricity to the earth ground, and thereby improve the capability ofthe whole device to guard against the electromagnetic interference. This PGND wire canalso protect the router against the lightning caused by the connection with the externalnetwork lines, such as E1/T1 line, ISDN/PSTN line.The grounding screw of 3Com 5000 Routers, which is marked with grounding label, islocated near the AC power socket and its switch on the rear panel of the chassis, asshown in the following figure:Figure 9 Grounding screw of the routerUse a PGND wire to connect the screw to the earth ground, and the groundingresistance should not be greater than 5-ohm. Likewise, if the router is installed in a19-inch standard rack, this rack is required to be grounded too.CAUTION: When the router is in normal operation, it is required to be well grounded.Otherwise, the router cannot reliably avoid lightning, which may damage the router itselfand even the peer device.(1) Power switch (2) AC input(3) Grounding terminal