Download Best Practices

Best Practices
Attachment Bracket Bonding
The equipment attachment brackets or “ears” must have good electrical contact
with the rack mounting rails. If the rails are painted, best bonding will be
achieved by carefully and neatly scraping away the paint where the ears butt
against the rails. To make a neat job use tape to mask off the rail where you do
not want paint removed. The prime purpose of ensuring a good electrical contact
between the radio and the rack is to minimize resistance to ground in the event of
a lightning strike.
• A satisfactory alternative is to rely on the grounding provided by the rack
fastening screws, but only if the rail holes are directly threaded and are clean of
any paint, and the rack screws are used without insulating washers under their
heads so that there is direct ground bonding via the rack screw between the
equipment and the rack rails.
IDU and Rack Grounding
All rack-mount equipment should be fitted with a grounding stud or bolt-hole for
ground wire attachment. This may be on the equipment chassis or on one of its
attachment brackets.
IDU Grounding - 4 Simple Rules
Follow these four rules when installing ground wires within a rack:
1. Each rack-mounted item of indoor equipment must be separately grounded to
the rack ground bar. Do not daisy-chain indoor equipment grounds.
• Figure 7-1 shows incorrect grounding practice.
• Figure 7-2 shows correct grounding practice.
2. The ground leads should be green or green/yellow, PVC insulated copper
stranded wire.
3. The ground leads must have a minimum wire size of 4 sq mm/14 AWG.
4. Only use the correct size ground terminals or lugs for the ground-wire size.
280-200019-001 Rev 005a June 2007
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