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Thread: Anyone use Isolated Ground receptacles for office or school's?

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    Anyone use Isolated Ground receptacles for office or school's?

    I am wondering if anyone out there still uses isolated ground receptacles in new installations for office/school PC's. Let me know why you do, or why you don't.

    Thanks

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    I can't think of any reason to use them with today's technology except to keep old methods from disappearing.

    Roger
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    Not in about 10-15 years.

    The need for the noise reduction is outweighed by the increased chance of increased noise as a result of attempting the IG installation.

    It went by the weigh-side along with oversized neutrals.
    Ron

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    Quote Originally Posted by Mr. Pickle View Post
    I am wondering if anyone out there still uses isolated ground receptacles in new installations for office/school PC's. Let me know why you do, or why you don't.

    Thanks
    No.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

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    BICSI specifically states not to use isolated ground receptacles.

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    Isolated ground receptacles were used back in the days when data processing equipment was interconnected with RS232 or coax (thinnet). RS232 and of course coax cables have a ground running from end to end which is tied to the frame or chassis ground of the equipment that it connects to. If pieces of equipment were powered from different circuits and/or different panels it was likely that a ground loop would be created that could disrupt data or damage equipment. Today's ethernet networks (and WiFi) isolate the equipment from one another so ground loops can't happen. So except for some audio installations, iso ground receptacles are no longer needed. But unfortunately because of ignorance we still see them specified.

    -Hal

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    Some of the the new 10G/40G CAT6, CAT6a and CAT7 RJ45 cables and connectors that are gaining traction are now shielded and grounded through both ends, though I would expect that the data channels are still galvanically isolated. We were just involved with planning for a high end tech office with IG specified throughout the network equipment rooms.


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    Quote Originally Posted by ccst View Post
    Some of the the new 10G/40G CAT6, CAT6a and CAT7 RJ45 cables and connectors that are gaining traction are now shielded and grounded through both ends, though I would expect that the data channels are still galvanically isolated. We were just involved with planning for a high end tech office with IG specified throughout the network equipment rooms.
    Still a waste of money IMHO. Even in shielded cables the signal wires are balanced differential pairs and isolated at each end, you might get some current flowing over the shield, but very unlikely to affect the data.

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    Isolated Grounds can do more than just provide protection from damaging RF noise.

    Looking at your question, as well as the feedback, got me to thinking about "Objectionable Current" and how the isolated ground assists in dealing with this unplanned current flow on the grounding system. I put it to print-

    The Isolated Ground (IG) typically serves a load or device in the form of an Equipment Grounding Conductor (EGC), which is shielded from excessive RF noise by donning a mandatory insulation for its entire length. On top of that, this Isolated Ground Conductor is required to stay remote (disconnected) from all other grounding splices within the grounding system, until it reaches its target: the EGC terminal bar inside of the panel.
    The purpose: To keep unwanted RF noise from entering our delicate electronics via the EGC.
    By insulating the IG conductor for its entire length, and prohibiting additional splicing on this conductor to boot, we are providing this equipment grounding conductor a path back to the electrical panel, without allowing it to ever touch another conductive metal on its way there; a conductive metal that may be serving as an antenna for RF noise, through its deliberate contact with structural, plumbing, and electrical metal throughout the building. The Isolated Grounding system is well known for its ability to thwart this nuisance "noise" on electronics, when RF is abundantly present.

    But... the Isolated Ground can also serve another purpose. It can function as the equipment grounding conductor (EGC) for a device or load, while providing protection for that load, from any "objectionable current" that may be occurring on the grounding system of that electrical system.
    Objectionable Current
    is not the same as RF Noise. Objectionable current is a measurable current that flows on the EGC system, that ought not be there, but is there due to some improper connection between a grounded conductor (aka white conductor) and a grounded metal surface, or grounding conductor, somewhere else within the system. Objectionable current can also be present because of a failure in a connected-load somewhere on the system, that is letting current bleed through an insulating material and on to the ground of that load, and as a consequence- on to the grounding system of the entire electrical system. This minimal amount of current that is often found on the grounding systems of large and/or older electrical systems, is typically of no consequence to normal inductive/resistive loads, and simply put, doesn't hurt anything. But for delicate Solid-State electronics, this minimal current on the equipment ground, can wreak electrical havoc.
    By using an Isolated Grounding conductor, andthen it (by default) not touching any portion of the potentially "charged" equipment grounding system metal, you have greatly reduced the possibility of that small electrical charge being redirected "upwards" through your load's EGC and into your delicate load's electronics. And instead, you have moved the point at which your load's EGC makes contact with this slightly charged equipment grounding system, so that it will be so far away from your delicate equipment, and so close to where the main bonding jumper (MBJ) ties the grounding system, into the grounded (neutral) system, that the objectionable current will have no choice at all, butthat choiceof "least resistance," whereby the current must leave the premises wiring - as well as your delicate electrical load altogether, and exit the premises by way of the service neutral, all the way to the grounded utility co. transformer.

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    Quote Originally Posted by JLDURHAM View Post

    The Isolated Ground (IG) typically serves a load or device in the form of an Equipment Grounding Conductor (EGC), which is shielded from excessive RF noise by donning a mandatory insulation for its entire length. On top of that, this Isolated Ground Conductor is required to stay remote (disconnected) from all other grounding splices within the grounding system, until it reaches its target: the EGC terminal bar inside of the panel.
    The purpose: To keep unwanted RF noise from entering our delicate electronics via the EGC.
    By insulating the IG conductor for its entire length, and prohibiting additional splicing on this conductor to boot, we are providing this equipment grounding conductor a path back to the electrical panel, without allowing it to ever touch another conductive metal on its way there; a conductive metal that may be serving as an antenna for RF noise, through its deliberate contact with structural, plumbing, and electrical metal throughout the building. The Isolated Grounding system is well known for its ability to thwart this nuisance "noise" on electronics, when RF is abundantly present.
    I think the only place you will see that argument is from some medical equipment manufacturers who use it to justify them requiring an iso ground and sometimes no ground at all, just a ground rod!

    Fact is there is no one magic way to remediate RF interference. What may work in one instance may actually make the situation worse in another. And certainly for the computers and equipment we deal with everyday, RF isn't an issue unless maybe you are next to a high power transmitter.

    Quote Originally Posted by JLDURHAM View Post
    But... the Isolated Ground can also serve another purpose. It can function as the equipment grounding conductor (EGC) for a device or load, while providing protection for that load, from any "objectionable current" that may be occurring on the grounding system of that electrical system.
    The only way you are going to have objectionable current flowing (ground loop) is when the equipment has another path back to ground that's different from the receptacle ground it receives power from. As was said, this was common with early interconnected equipment that used a ground conductor in the cables that interconnected them. We don't have that problem today because there is no grounded conductor, or the designers took steps to isolate the grounds at the equipment.

    You also have to understand that rarely will you find an iso ground receptacle installed properly. So you can infer from that, that if the situation were as serious as you say there would be all these problems. Never will you see individual grounds from iso ground receptacles run individually back to the main panel ground bus as they should be. Many times that would be impossible. What you will find is that they are all spliced together and run to the panel that is supplying the circuit. Why bother?

    -Hal

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