Isolated Computer Receptacles

[Jim_BE]

I am doing a project for an internet distributor. The spec's call for isolated ground receptacles for all the computer circuits which is not a problem. The question is do I need to truly isolate these grounds through an additional conductor and insulated ground bar in the sub feed panel and then back to the distribution panel? Do I then carry this ground to a separate ground rod(s) without connections to the distribution panel. I know part of the reason for this process is to reduce "noise" in the lines but how far does it need to go? :-? :-? :-?

 

[iwire]

It should be in the job specifications.

The preferred way of people who believe IGs are needed is this.

An isolated ground all the way from the grounding terminal on the IG receptacle all the back to the bonding jumper at the service equipment OR the bonding jumper at a transformer whichever comes first as you follow the circuit conductors back.

If you have panels along the way you install isolated grounding bars and you can consolidate all the branch circuit IGs onto one IG ground bar, from that bar you run one isolated EG back toward the bonding jumper.


Just a question.

Are these servers going to be mounted in racks?

 

[hardworkingstiff]

The preferred way of people who believe IGs are needed ....

You can count me out of this crowd. I would love for someone to explain how an IG is any better than a good solid ground. It seems to me to be a coverup for poor electronic circuits.

 

[Jim_BE]

Thanks I wire for the response...yes..as far as I know they are all rack mounted... this network guy is a little "aloof" .... as to the details of his installation....

 

[iwire]

yes..as far as I know they are all rack mounted...

That rack mounting pretty much makes the IGs meaningless.

(Of course that assumes they where of value to start with)

 

[dbuckley]

I would love for someone to explain how an IG is any better than a good solid ground. It seems to me to be a coverup for poor electronic circuits.

Add me to the list.

Is there anyone here willing to vote that there is a place in IT for IG sockets?

Bearing in mind that the rest of the world has never heard of an isolated ground socket, it's pretty much an American phenomenon, and given the rest of the world uses the same IT kit (HP, Cisco etc) that you guys do, why it works in the rest of the world on normal sockets but needs IG in its country of origin. And especially given the state of the electrical systems in many parts of the world...

Call me baffled...

 

[iwire]

As I understand it it did have a place when the interconnections between equipment included a ground reference like when coax was used or the original IBM type interconnections where used.

But that is just hearsay.

 

[yrman123]

Part of a job I'm doing iincludes running a #6 ground to data cabinets or racks. Some of the cabinets have a built in grd bar; when I connect to this bar and I test I get a poor reading(600-900). When I go to the frame I get a good reading(usually less than 1 ohm). What's the point of the bar in the cabinet? Could it be a defect of some sort?

 

[dereckbc]

Thanks I wire for the response...yes..as far as I know they are all rack mounted... this network guy is a little "aloof" .... as to the details of his installation....

Well take it from a engineer, and tell your IT guy as soon as he installs his first piece of equipment in a rack and plugs the cord in, all that expensive IGR he paid for just got thrown in the trash can and compromised.:roll:

 

[dereckbc]

Part of a job I'm doing iincludes running a #6 ground to data cabinets or racks. Some of the cabinets have a built in grd bar; when I connect to this bar and I test I get a poor reading(600-900). When I go to the frame I get a good reading(usually less than 1 ohm). What's the point of the bar in the cabinet? Could it be a defect of some sort?

You should read almost 0, if not something is wrong.

 

[ItsHot]

isolaters

isolaters

Well take it from a engineer, and tell your IT guy as soon as he installs his first piece of equipment in a rack and plugs the cord in, all that expensive IGR he paid for just got thrown in the trash can and compromised.:roll:

You have to mount the equipment on approved "isolaters"!

 

[dereckbc]

You have to mount the equipment on approved "isolaters"!

Well this is true, but I have built a lot of data centers, and in everyone of them folks install equipment without the isolators, or intercoonect I/O ports with coax or someother ground referenced signal medium. There is no way to Police it. In fact the two biggest Telephone companies who build data centers refuse to use IGR for that very reason and only use SGR fed from a PDU. There is no better mehod for eliminating Common Mode Noise than a PDU with SGR.

 

[noonan]

.. this network guy is a little "aloof" .... as to the details of his installation....

Hmmm, an IT guy that is aloof? Surely an "isolated" case!

 

[jrclen]

There is no better mehod for eliminating Common Mode Noise than a PDU with SGR.

That's for darn sure. (what's a pdu with sgr?) I don't care what it is, with your permission, I'm using that line down at the bar later. :grin:

 

[dereckbc]

(what's a pdu with sgr?)

PDU = Power Distribution Unit. Basically a self contained isolation tranformer that has built-in distribution, alarms, bells, and whistles used in data centers fed via delta from a UPS or service.

SGR = Solid or standard Grounded Receptacles, vs IGR = Isolated Ground Receptacles

 

[jrclen]

PDU = Power Distribution Unit. Basically a self contained isolation tranformer that has built-in distribution, alarms, bells, and whistles used in data centers fed via delta from a UPS or service.

SGR = Solid or standard Grounded Receptacles, vs IGR = Isolated Ground Receptacles

Got it, thanks. I have no experience with a PDU as far as I know. I have installed a couple 20 KVA (208v) UPS units for data centers. Both jobs had me connect a 480 delta to 208 wye transformer which then supplied the UPS unit. That fed a 3 phase 208 panel for the data equipment in the room. One of those jobs called for isolated grounds and the other didn't. One had a grounded tile floor which I found interesting. I had to connect copper straps from the floor to an EGC to the panel. In these cases all the bells whistles and alarms were in the UPS units.

 

[Jim_BE]

Thank you Dereck for the input .... you have just repeated what I have been trying to explain to this IT guy from the beginning of the project ... but he wants the racks grounded and insists that we install IG receptacles ... so be it .. that is what we are doing ... :grin: The funny thing is that he has not spec'd any surge protection on the sub panel feeding all these computer circuits but is putting a power strip (over the Best Buy counter of unknown joule rating ):-? :-? :-? type in each rack. I have more protection on the CCTV, Fire and security panels. I am having him sign off on our installation when we are finished for obvious reasons...Thanks again

 

[iwire]

but he wants the racks grounded and insists that we install IG receptacles ... so be it .. that is what we are doing ... :grin:

The customer is the customer, as long as what they want is not unsafe I just do it and charge them for it.

 

[ghostbuster]

A properly designed I.G. system can solve a multitude of problems,especially in high end audio/video studios.

 

[dbuckley]

A proper non-isolated grounding system will also work just fine for A/V, and does so in the rest of the world; audio rarely gives problems (all balanced) but analog video with all its unbalanced connections can be a total nightmare...