grounding/bonding IT equipment

[torledo]

Hi All

We're in the UK, and we've been looking into best practice regarding earthing and bonding of our equipment...i understand most of the components of a telecomms earthing system, well atleast i think i do...

but i'm not sure which equipment needs to be bonded, and whether to bond at equipment level or at rack level....

For example, should we be connecting our servers to a grouning busbar...there is no ground point on dell, hp servers etc. so does that mean they don't need to be grounded ?

Similarly some of our AC powered Cisco kit have grounding points e.g PIX, IDS but our newer switches don't..and the cisco docs only refer to grounding DC-powered 3750, no reference to the grounding of AC switches.

 

[SYQUEST]

If you can get a copy of the PANDUIT® Pan-Net® Network Solutions catalogue, they have examples of wiring and hardware for data centers, racks, cabinets, etc. They show some good pictures too. I don't know if that catalogue can be downloaded, but their website is

http://www.panduit.com

or contact the UK distributor.

I know there are other companies that make similar hardware, but I am familiar with Panduit and have used their products.

Also, if the switch or router, etc. does not have a ground/bond lug you might contact the company and ask if they have any suggestions that might apply to your installation.

....JIM....

 

[franklin97355]

Most equipment will be grounded through the chassis and needs no other ground. You do need to make sure that your racks and ladders are bonded to earth either through another piece of structure or directly. In the US we have the National Electrical Code and state and local rules that specify how things are to be done but I don't know how it is addressed over there. Also most manufacturers of racks and data center structure will have info on their websites about connecting and bonding their devices.

The answer is "42"

 

[torledo]

@syquest, franklin

i've managed to download an image from the panduit website illustrating applications of their bonding products.

They have a cabinet ground strip that runs vertically on both sides of the rack to bond the bare metal rack rails of servers to the busbar connection point at the bottom of the rack.

I'm just wondering if this is necessary for servers whose chassis are already grounded as franklin has said.

Unfortunately manufacturers don't tend to provide any information on grounding the equipment unless it's DC....i assume this is becuase the chassis are grounded internally.

My last question is in regards to a device like my pix515...it is an AC device and yet has a ground point on the chassis. Cisco don't provide any info on whether it needs to be grounded at the ground point.

Does bonding racks and cable ladders to the common grounding busbar mean that all equipment inside the racks need to be at equipotential...in which case is a ground strip like the one on the panduit website essential for use in server racks ?

 

[SYQUEST]

You will probably get some yeses and noes about whether you should bond to that level. The main things are safety, EMI/RFI, and TVSS - equipotenial. Having all the racks and major items, like servers, U.P.S., etc. bonded/grounded provides that extra "surface area" for keeping everything at the same level. Items like the PIX, if it has a terminal provided, then use it if you feel so inclined. If the history of the facility shows problems with power quality, then things need to be scrutinized much more carefully.

I think the most important thing is making sure all the major wiring for the bond/ground system is tight, secure and maintained.

....JIM....

 

[RikRodgers]

Usually if equipment has a ground lug out of the box, I ground it. If it doesn't, I don't.

Grounding your equipment is not just important for surges, but for a clean ground referrence for the circuits in the equipment you're installing. Improper grounding can lead to some really weird issues in your network.

In my opinion, I don't rely on the NEC's "good enough". If the equipment manufacturer's engineers felt strongly enough about grounding to put a ground lug on the hardware, then I'll go the extra mile, and run wire.

My opinion is the product of training I received as a 29M. Thanks, Uncle Sam.

 

[torledo]

rik, thanks for the advice.

We're a small facility where we don't have a raised floor in either of our server and comms rooms, all cabling must go over head.

We're in a position at the moment where we intend to purchase a three phase UPS from which all rack pdu's will be connected....all electrical distribution boards in the facility are grounded, and we have a ground point at the entrance facility where water, ceiling grid, vent systems ground wires meet.

When we get round to having the ups and pdu's installed and when we have new overhead mesh cable baskets and ladder racks installed what advice can you guys give as to how far we should take the process of bonding our racks/equipment...

if the equipment racks are to be bonded would we need to implement some sort of cbn overhead....all the examples of cbn i've read about reference the raised floor tile structure not overhead.

I've read that ladder rack sections should be bonded, but what to we bond to if we don't have a common bonding network....i would imagine it's not best practice to connect to other grounding networks such as the ceiling grid or ventilation system ground network.

 

[RikRodgers]

The other department of the company I work for installs bays for Telco's. (ATT, etc...) They're required to strap each rack they install to an adjacent rack that's connected to earth ground. It's a good practice.

If there are no racks in place, run ground wire to a cold water pipe,(and make sure the pipe is ground jumpered at the meter- otherwise your ground could actually have 6vdc on it rather than 0vdc) or to structural steel (an I beam).

If grounding is a paramount concern for you, I'd call a local electrician to provide you a ground bus. This puts the responsibility on their shoulders, and they shouldn't charge you a lot for this, anyway.