Technology Notebook

Grounding and Bonding Datacom Systems: "Telecommunications main grounding busbar (TMGB). The TMGB is the dedicated extension of the building grounding electrode system for the datacom infrastructure. Because it's the central attachment point for TBBs and equipment, it should have easy access by datacom personnel.
The TMGB is a predrilled copper bus bar with standard NEMA bolt-hole sizing and spacing for the particular lug connection used. It should be large enough to satisfy today's applications and accommodate future growth. The TMGB should have a minimum thickness of 6 mm and width of 100 mm. You'll find varieties of ground bars available, and some come as a kit you can customize to meet specific requirements of the application. Pre-welded exothermic pigtails are available in a variety of conductor sizes and lengths, insulated or bare, ready for your attachment to the building ground.
Electrotin plating results in reduced resistance. However, you must completely clean any mating surfaces if they're not plated. If you have datacom panelboards located with the TMGB, you must bond the alternating current equipment ground bus (or metallic enclosure) of each to the TMGB/TGB. Make sure you maintain appropriate clearances when locating TMGBs as close as possible to the panelboards."