Computer room Ground Bus Question

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detroitelectrician

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Anyone have any experience installing ground buses? Yesterday I got a call to install a ground bus for a computer room. They have no prints, specs, or any Idea what they need. Someone told them they need a ground bus to protect the computers. It is a small ccomputer room with only four computer racks. The computer room is on the second floor of a office building. I have a limmited knowledge of computer rack system grounding. So I ask , if I bond the racks to a ground bus and cadweld the bus to building stell would that give them the protection they need? And is that how it is normally done?

Thanks for any comments, Mike
Michigan Master Electrician
 
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That is a very open question in my opinion, with out drawings they are relying on your expertise, which you admit is limited in this field.

Did a manufacture request this?

Did the end user expierence problems?

Did the data center manager just return from a seminar?

There is a fair amout of literature availiable on the web regarding.

I did not review this site just included it for a starting point for you.

http://www.panduit.com/enabling_technologies/102200.asp
 
This is a new install

This is a new install

Thanks Brian, this is a room under constrution now. The data guy has seem ground buses at other locations so hey thought it was a neccessary part of a computer room. The racks are not even installed yet.
 
Most small computer rooms I'm seeing don't have a ground bus at all (heck, some of them are converted offices, with carpet). The racks might have a #6 insulated lead from rack to rack to the nearest panel. If they're using proper power distribution equipment (not plastic plug strips), the EGC in them grounds the the equipment frames.

That said, it woulnd't hurt to install a proper ground bus at this point.
Here's another one http://www.smccd.net/accounts/itwirespecs/cable/riser.htm
 
petersonra said:
Just what constitutes a proper ground bus?
Click to expand...

I just love easy questions. Electrical Protection of Digital and Lightwave Telecommunications Equipment (PDF 560K), from the US Department of Agriculture (of all people), start with the illustrations on pages 30 and 35.

The benefits are the reduction of ground induced noise and spikes in the data centre, so elimination of buzzing on phones, and equipment doesn't get fritzed when lightning does its thing. Plus, and this may be the most important thing, it adds to your bottom line.

Of course very few installations do this properly, so it's just as well that modern computers are fairly forgiving beasts.
 
Thanks you guys for the excellent references. Dbuckley's USDA may seem strange, but is a great resource for many electrification and telecom loans in addition to the technical RUS specification given. For an overview of both main frame and small office network computer grounding, the page 35 Grounding diagram is worth looking at for the different bonding classifications used. rbj
 
detroit:
Another good source is Cisco grounding-bonding rack, chassis and building bonding network systems at http://www.cisco.com/en/US/products/hw/switches/ps3873/prod_installation_guide0 and note that Panduit is a technical partner with cisco in computer network technology. rbj

edit note: the word ...llation is supposed to be installation. Why doesn't the url spell this out correctly?
edit 2: Google up cisco MGX 8800/8900 installation guide if the url is capuut.
 
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Refer to 250.64(C)(3) in the 2005 NEC. This may give you an indication of what they are requesting. This has been used in network installation for some time and gives you a convenient centralized point to connect grounding conductors for cabinets, etc along with the GEC.
 
The best place to land computer room GEC

The best place to land computer room GEC

I received my computer room ground bus in the mail today from Newton instrument. Thanks for your help guys but I have more questions.
The computer room is on the second floor of a 8 story office building. My question is will it be okay to run a #6 to the closest building steel to ground my ground bus? Or do I have to run all the way to the basement (150 ft away) to attach to the incomming water supply . Someone from Newton instrument company told me if you use building steel and the building is hit by lightning it might fry the computer equipment. There is a large ground bus in the transformer room (13.2v x 480v) in the basement which is already connected to the water supply pipe, can I connect to that?

Really, what I am asking is what is the best way to do it?
 
Look to see if there is a ground buss riser. If so bond it to the riser and to building steel as close as possible on the same floor where it will be used.
 
dereckbc said:
Look to see if there is a ground buss riser. If so bond it to the riser and to building steel as close as possible on the same floor where it will be used.
Click to expand...

There is no ground bus riser, would it be okay to just go to building steel and be done? And still be protected from lightning?
 
Yes bond to BS as it is the best in a multi-story occupancy to prevent lightning damage to equipment and personnel. Mount it on or near as possible to a steel column or beam to facilitate keeping the bonding jumper as short as possible.

Purpose is to have a strategic location to bond SDS Xo terminations like those found in PDU?s, isolation transformers, and origination of signal grounds (antiquated), and equipment/racks/frames grounds.
 
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