Thank you for your question regarding low & medium voltage grounding systems within a telecommunications data center. It is our pleasure to help.
The primary concern with inter-mixing grounding systems between low-voltage & medium-voltage (or high-voltage) systems, is that the medium-voltage systems can generate electrical noise, transients, and harmonics that are far more intense than those generated by low-voltage systems; and introducing those intense & interfering signals onto the low-voltage side could cause problems. ANSI-TIA-EIA-J-STD-607-A is currently one of the more prominent grounding and bonding standards in use for data centers, and while it does not specifically call out for the separation of low & medium voltage systems, it does ask for some logical separations.
The basics of the ANSI-TIA-EIA-J-STD-607-A standard calls for a Main Telecommunications Ground Bar (MTGB) to be properly installed in the building with multiple Telecommunication Ground Bars (TGB) installed in logical order such as rooms or subsystems. The MTGB and the TGB’s are to be bonded together via a looped ground conductor called the Grounding Equalizer (GE) or sometimes called the Telecommunications Bonding Backbone (TBB). There are many rules and requirements regarding how these ground bars are bonded, what they are bonded too, and how the GE is routed and sized. This includes bonding to a grounding (earthing) electrode, building steel, water-main, and the main electrical panel; all tied to the MTGB. You should refer to the ANSI-TIA-EIA-J-STD-607-A for more details.
It is important to note that there are numerous standards that may apply to your situation, which will add additional requirements for your system. Often this includes having a dedicated 5-ohm or less grounding (earthing) electrode, lightning protections systems, and Human-Safety studies to protect personnel and equipment from hazardous Step & Touch Voltages from back-up generators.
It is of course hard to advise without looking at the plans, but for your situation you could install a Low-Voltage Telecommunications Ground Bar (LV-TGB) and a Medium-Voltage Telecommunications Ground Bar (MV-TGB) in the same room (labeled appropriately of course). These two separate ground bars, the LV-TGB & MV-TGB, would then be simply bonded to the Grounding Equalizer (GE) conductor loop. This would allow you to keep the two systems separated, without having to make massive additional conductor runs back to the MTGB. Of course, it is also possible to run two separate GE loops, one dedicated for low-voltage and the other for Medium-voltage, depending on how serious the level of protection is needed. Of note, the lower the resistance-to-ground of the ground (earthing) electrode, the more effective the entire system will be in removing the unwanted electrical transients.
If you should have any further questions, feel free to call us and one of our engineers will be happy to discuss your project with you free of charge.
The Engineering Team at E&S Grounding Solutions
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