Ask yourself this…
Is your data cabinet electrically safe? I would guess that most of you would say yes, but go and check and see if there is an earth cable attached. I would hazard a guess that many are not. If your cabinets are earthed, then good for you. And because of this, you’re surely protected against any legal/safety liability, right?
Have the correct size cables been used? I can almost hear the cry: “The earthing system was designed by the electrical engineers, so it must be right!” The truth is that there are differing standards within Europe and around the world specifically relating to this subject. Sadly, cabinets (when earthed at all) are often earthed with an all-too-small conductor that does not meet local/regional design codes and Standards.
The good news: it is only difficult if you get it wrong the first time and need to fix it.
Over the pond in the US, Carrie Higbie put together a brief overview of earthing/grounding for shielded cabling that also provides the core concepts of earthing cabinets and racks: http://www.siemon.com/us/white_papers/06-07-20-grounding.asp
If you’re based in Europe and looking for more detailed info, try this: http://files.siemon.com/int-download-guides/11-03-04_fb-emea-guide-grounding-bonding-cenelec.pdf