# Computer equipment grounding?



## griz (Nov 26, 2009)

Can any of you Sparkies tell me why computer server racks, MDF's & IDF's would need to be grounded by a #6 wire to the building bus? All are plugged into 110v grounded outlet. This is pretty much how the spec is written & it is in a school.


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## SLSTech (Sep 13, 2008)

What happens if a wire falls down from the ceiling, or something else touches that rack & energizes it?


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## griz (Nov 26, 2009)

SLSTech said:


> What happens if a wire falls down from the ceiling, or something else touches that rack & energizes it?


Server racks are in secured closets/rooms. IDF's & MDF's are in locked cabinets in classrooms. Not sure where a wire would fall from or where anything would touch a cabinet. They are also min. of 5' off the floor.


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## rselectric1 (Sep 20, 2009)

Not sure of the logic on that one. (I'm just a lowly residential guy)

I think you need to shine the bat-signal (err 480) signal on that one!:clap:


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## griz (Nov 26, 2009)

rselectric1 said:


> Not sure of the logic on that one. (I'm just a lowly residential guy)
> 
> I think you need to shine the bat-signal (err 480) signal on that one!:clap:


Yup, that's what I am hoping for. :thumbup:


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## s.kelly (Mar 20, 2009)

There is often a grounding grid in the raised floor in computer rooms to keep potential the same for noise issues etc. If I am understanding you correctly this sounds like a similar situation.


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## griz (Nov 26, 2009)

s.kelly said:


> There is often a grounding grid in the raised floor in computer rooms to keep potential the same for noise issues etc. If I am understanding you correctly this sounds like a similar situation.


No raised floor. Racks are to be installed on a slab. IDF's/MDF's bolted to walls.


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## Kgmz (Feb 9, 2007)

It is required by NEC code.

And that is why all racks have a ground attachment point usually at the bottom of rack. And also the electrical noise issue that s.kelly mentioned.

And here is a brief article on why and how.
http://redigitaleditions.com/Olive/...pageno=MTA.&entity=QXIwMTAwMQ..&view=ZW50aXR5


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## griz (Nov 26, 2009)

Kgmz, Thank you for the article link.


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## mwhafner (Oct 19, 2008)

> Server racks are in secured closets/rooms. IDF's & MDF's are in locked cabinets in classrooms. Not sure where a wire would fall from or where anything would touch a cabinet. They are also min. of 5' off the floor.


That is not an accurate statement.



> Can any of you Sparkies tell me why computer server racks, MDF's & IDF's would need to be grounded by a #6 wire to the building bus? All are plugged into 110v grounded outlet. This is pretty much how the spec is written & it is in a school.


The reason is really a "normalized" ground potential and noise drain, and has more to do with the structured cabling than the servers and equipment.



> It is required by NEC code.
> 
> And that is why all racks have a ground attachment point usually at the bottom of rack. And also the electrical noise issue that s.kelly mentioned.
> 
> ...


Great article, thank you for posting.


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## griz (Nov 26, 2009)

mwhafner said:


> ...That is not an accurate statement....


What's not accurate?


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## elkhornsun (Jul 9, 2008)

Actually the goal is to have an isolated ground for the computer equipment which is easily damaged if there is current on the ground and in some cases it will also with a floating ground prevent low voltage equipment from operating properly as the on/off state difference in voltage can be reduced by 40% quite easily. You can pretty much walk into any building, old or brand new and find problems with voltage on the ground line. No big deal if a refrigerator or hot plate is plugged into the wall but another story if it is server rack that is going to cost many thousands to replace.


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