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Last Login: Monday, March 08, 2010 1:32 PM
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| | I have a client who has been given a design for a bonding and grounding system in a computer room that includes using a 750 MCM to bond the TMGB to the main building electrical ground. They are also specifying that the user run discreet #6 ground wires from EACH cabinet, Rack, cable tray etcs directly back to the TMGB. My interpretation of the J-STD-607-A is: Max size for a BC is 3/0; cannot bond serially, however you can bond to a ground wire run as a bus through a cable tray (for example), and bond each wire coming from a cabinet below to it. Help and thoughts anyone. My client trusts this designer and I believe he means well, however this looks more like a 48V DC ground system and NOT a standard, telecommunications ground system. Furthermore, my clients budget is stretched to the limit and saving him thousands of dollars on the ground system would be very beneficial if possible. Thank you. |
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Last Login: Tuesday, January 03, 2012 12:48 PM
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| I would tend to agree with you on the conductor size. I stop at 3/0 or 250 MCM. As for the cabinets or racks, you can run a backbone past all of them and H-tap down to or up to each rack or cabinet. I have done this on a few projects with good results. I do require they bond that backbone twice to the bar just like is recommended for a floor grid (they have to disconnect two lugs to diconnect all the cabinets). Don't know if the "grounding gods" would approve of this, but it has served well for me. See attached diagram.
Ryan Hall, RCDDMorrissey Engineering rhall@morrisseyengineering.com
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| | | Forum Newbie
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Last Login: Monday, March 08, 2010 1:32 PM
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| | Thank you very much Ryan. Appreciate the time and the sample design. Very helpful. Robert |
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