Isolated Ground for Computers and associated equipment

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Anil

New member
Location
New York City
We are a New York City Agency and have been using electrical standards for many years which requires PC's and associated equipment such as scanners , printers etc to be provided isolated ground and each individual circuit carry a separate neutral.All such equipment is wired to dedicated computer panels and convenience receptacles are wired to separate panels without isolated ground.

Currently what I hear and read from experts is that this method of providing isolated ground is old and not required any more. One of the reason given is the cost, and the modern computers are more resilient to distortions and transients due to non-linear loads in the system . Besides other means are available to provide clean power, one using surge suppresors and the other by K rated transformers etc.

Before we review the agency's standards for updates I would like to know your opinion and experience in general on this isolated grounding issue. Thanks.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Isolated grounds are pretty much wastes of money and resources. I agree with using surge protectors but that is not for actual power quality as much as for what the name indicates they are for.

K rated transformers are a good idea in buldings where there will be high quantities of electronic equipment connected to them, but this is for the transformers protection more than it is for the branch circuits.

Roger
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Engineer
Currently what I hear and read from experts is that this method of providing isolated ground is old and not required any more.
It became old and not needed almost 15-20years ago. About the time that printers and computers became interconnected with 'ethernet' cables.
 

t1882

Member
Location
Idaho
Isolated grounds are pretty much wastes of money and resources. I agree with using surge protectors but that is not for actual power quality as much as for what the name indicates they are for.

K rated transformers are a good idea in buldings where there will be high quantities of electronic equipment connected to them, but this is for the transformers protection more than it is for the branch circuits.

Roger
It became old and not needed almost 15-20years ago. About the time that printers and computers became interconnected with 'ethernet' cables.
I agree, waste of time and money.
 

hurk27

Senior Member
Back in the day of T10 networks, 485's and others that had a parallel path that also used the EGC as a reference path this was a problem when noises and stray voltage/current was also on the grounding path would introduce data error's on the parallel signal ground path, today slowly (very) more and more manufactures are getting away from referencing the EGC and networks are using more and more non-EGC paralleled balanced type wiring or FIOS.

While there are a few manufactures who want to hold onto using the EGC as a signal reference it is and has always been a mistake and will always be a problem until they move away from this, I still get calls on having more then .5 volts between the neutral and EGC, mainly from service tech working on multifunction copier machines, they will try to tell me my ground has voltage on it, what they don't realize is, its not the ground but the neutral that has a voltage drop on it, and this creates a difference of potential, it is almost imposable not to have some kind of a voltage drop on a neutral, many circuit runs in a commercial office or store will have runs in excess of a 100', why should this be a problem to a copier? because it references the EGC.

Even vehicle manufactures realized this with the introduction of computers into cars, and it didn't take them as long to start keeping the signal paths and power paths seperate we now have almost every load in a car using its own negative wire return to a common point instead of using the body.
 

augie47

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Staff member
Location
Tennessee
Your question related specifically to the isolated ground and I agree 100% with the other posters.

In your original post you did also mention separate neutrals. I would say, in my opinion, that is still a good idea mainly as the new requirements for multi-wire-branch circuits introduce the fact that if one circuit is tuned off or "trips", you will loose the other two or three "shared" circuits also.
To reduce the number of pieces of equipment that may be turned off due to one fault, I would still suggest separate neutrals.
 
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