Grounding Isolation

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chamolinian

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We are in a project installing Foundry switches for this site. The local Communication support group wants us to isolate the communication ground from the electrical ground. Is this common practice when installing communication equipment? We've done other projects the same as this one but this is the first time we got this request for isolation. Can someone support this question with some explanation that will show the overall picture of the entire grounding pertaining to the question? These particular equipment requires good ground and where we're at presently (Delta Junction, AK.), getting good ground is a challenge in this area. I will appreciate any comments, recommendations, or any technical support on this matter, thank you.
 
Re: Grounding Isolation

I think you might start by defining a "good ground".

Keep in mind that no matter what you do, at some point all of these things have to be tied together. Even so called isolated grounds are not really isolated. They are just tied together at the service point rather than out in the plant somewhere.

You should get some definition of what specific requirements the equipment supplier wants, rather than some vague thing like a "good" or "isolated" ground.
 
Re: Grounding Isolation

You may want to refer to AT&T Standards and Practices (which the telcom industry recognizes as their engineering standard. ATT 803-501-100 Issue date September 1998. They define two different types of grounding systems utilized for telecommunications. Isolated and Integrated. In short (no pun intended) the integrated system is one that ties to building steel or whatever else is utilized in the building as a path to earth. Isolated is where the telecommunications equipment is deliberately seperated from the integrated ground system, building steel or "any other incidental conductive path to ground except at a single point called the GROUND WINDOW. The isolated ground point is utilized with electronic switching systems such as the 5ESS and 4ESS." Basically, unless you are installing a true switch which the 5ESS and 4ESS are, you should use the integrated ground system.
 
Re: Grounding Isolation

Flyersfan, actually the standard is Bellcore TRW-000295, and many more like the one you mentioned is derived from that.

chamolinian, you need to define ISOLATED. If by that you mean there is no planned bonded connection to the electrical earth ground electrode system, that would not comply with 250.4(5) and 250.58, therefore that is all they need to know. It would not fly or pass inspection... Secondly if you did that, the telecom equipment would eventually be destroyed, likely suffer from operational issues like resets, noisy circuits, or not function at all, not to mention how dangerous it would be to personnel.

If by isolated you mean an "Isoalted Ground Plane" or "Isolated Bonding Netowork", or one of the dozen other names it goes by, then I would suggest you are in way over your head and need someone who speicalizes in telecommunication power and grounding design/build.

[ October 20, 2005, 05:52 PM: Message edited by: dereckbc ]
 
Re: Grounding Isolation

Dereckbc,
My AT&T engineering friends beg to differ. Regardless, it's relatively the same information and standards. Chamolinian, it's a worthwhile read if you plan on doing any telecom power work. Also if you're having trouble sleeping :p
 
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