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Old 02-22-2009, 04:35 PM   #16
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Isolated Ground Receptacle


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You shouldn't worry about isolated grounds, just run a ded line to your recs and use plastic boxes.

I remember a diy book suggesting to use 14/3 and color the red with green tape

I'll find it if any of you want to see the violation.
It seems that we hijacked the OP thread! In his case, isolated grounds for a computer are unnecessary!
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Old 02-22-2009, 05:03 PM   #17
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Isolated Ground Receptacle


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I remember a diy book suggesting to use 14/3 and color the red with green tape

That's the Black and Decker complete quide to wiring. This book is exactly what started this conversation. I was reading this morning about IG receptacles and how to use 14/3 and green tape the red. If this is a code violation, now some people will see why I have a nasty habit of asking several sources the same question. Thanks for your time and input.
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Old 02-22-2009, 05:47 PM   #18
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Isolated Ground Receptacle


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That's the Black and Decker complete quide to wiring. This book is exactly what started this conversation. I was reading this morning about IG receptacles and how to use 14/3 and green tape the red. If this is a code violation, now some people will see why I have a nasty habit of asking several sources the same question. Thanks for your time and input.

Reason why its wrong is because red is usually a current carrying conductor color. Re identifying such colors for ground is not allowed.
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Old 02-22-2009, 09:03 PM   #19
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Isolated Ground Receptacle


Thanks for clearing that up. Very helpful.
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Old 02-22-2009, 09:08 PM   #20
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Isolated Ground Receptacle


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Thanks for clearing that up. Very helpful.

Your welcome
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Old 02-23-2009, 06:44 AM   #21
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Isolated Ground Receptacle


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Back in the 70's I worked at a university that had many different types of labs. with just about every bit of electronic gear that you can imagine!
Problems developed where noise traveled along the current conductors and back on the grounding! If my memory serves me right, it was known as 'longitudinal' noise!
To prevent this current loop, we ran the ground from the receptacles back to a ground rod, rather than back to a ground bus in the panel.
The position of the isolated ground recepts. in a circuit has no bearing on its function.
Isolated grounding recepts. have no electrical connection from the ground pin to the mounting bar! This allows a clean ground for equipment all the way back to earth!
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Maybe its against the NEC code, but this is exactly the way its done here in Ontario! Its the only way to prevent false signals from being carried into critical medical equipment! Isolated ground receptacles are made to isolate the ground!
How do you connect a isolated ground receptacle in your area?

Sorry Chris, but all grounds go to the planet earth! Ever hear of a ground rod?
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The only way that 'crap' could be kept from corrupting medical equipment was install a separate ground bus in the panel. The isolated ground recepts. had their own insulated (green) ground conductor that found its way to the separate, isolated ground bus, that in turn had a insulated cable that was run either to a ground rod or to the structural steel!
This arrangement is similar to what a 'star' data network would be, whereas if the grounds return to a common bus, it forms a loop much the same as a 'ring' data network! A loop allows currents to flow! Its these currents that cause the problem!
WOW!

I am speechless.

Canada or not, this is SO wrong it's not even funny!
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Old 02-23-2009, 07:07 AM   #22
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Isolated Ground Receptacle


Wow, that is a big

Couldn't they have used filters or isolation x-formers before messing up the wiring?

Did that university ever have a fire? Or did somebody get killed from electrical shock? Sure seems like that would happen with an install like that.

PS. Grounds go to earth for high voltage or lightning events. They are connected to the neutral for fault clearing.

Last edited by rgsgww; 02-23-2009 at 07:09 AM.
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Old 02-23-2009, 07:36 AM   #23
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Isolated Ground Receptacle


I don't know what I am talking about so you can stop reading here< if you wish. If I understand Wildie he is saying that there is an extra ground bus in the panel connected to it's own ground rod. The equipment you want isolated is connected to this extra ground rod, the rest of the equipment, lights, etc. is connected to the other ground bus. In plain english, why is this wrong? You not allowed to have two ground busses in a panel? They must be attached to the same ground rod? Just trying to educate myself. I try to learn one new thing everyday this will be today's lesson. Thanks for your time.
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Old 02-23-2009, 08:17 AM   #24
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Isolated Ground Receptacle


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If I understand Wildie he is saying that there is an extra ground bus in the panel connected to it's own ground rod. The equipment you want isolated is connected to this extra ground rod, the rest of the equipment, lights, etc. is connected to the other ground bus. In plain english, why is this wrong? You not allowed to have two ground busses in a panel? They must be attached to the same ground rod?
It is wrong because sticking a rod in the ground DOES NOT provide a "ground". At least not in the sense of a safety ground that will clear a fault in the event of a short circuit or fault to something conductive. That safety "ground" is not actually a ground, but the neutral BOND in the main panel.

The only reason your description above would be safe is that all the ground bars are bonded to the panel enclosure which is eventually bonded to the service neutral (grounded conductor). If the bar were isolated/insulated from he metal panel then it would NOT be safe and NOT be effective.
A rod in the ground does nothing to clear a fault.
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Old 02-23-2009, 08:26 AM   #25
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Isolated Ground Receptacle


I am interested to hear Wildie's response to this thread! The way Wildie has described those Isolated Ground recepticals are wired is very wrong!
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Old 02-23-2009, 10:25 AM   #26
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Isolated Ground Receptacle


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Originally Posted by Speedy Petey View Post
It is wrong because sticking a rod in the ground DOES NOT provide a "ground". At least not in the sense of a safety ground that will clear a fault in the event of a short circuit or fault to something conductive. That safety "ground" is not actually a ground, but the neutral BOND in the main panel.

The only reason your description above would be safe is that all the ground bars are bonded to the panel enclosure which is eventually bonded to the service neutral (grounded conductor). If the bar were isolated/insulated from he metal panel then it would NOT be safe and NOT be effective.
A rod in the ground does nothing to clear a fault.
Thank you for clearing that up. I understand now. Thanks for your time.
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Old 02-23-2009, 10:39 AM   #27
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Isolated Ground Receptacle


In wildie's situation I would have tried a filter like this

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Old 02-23-2009, 12:22 PM   #28
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When I was employed at the university, I was working under the direction of the Director of Physical Plant. A professional, electrical engineer!
A problem was encountered, with contamination of results obtained from sensitive electronic equipment.
Previously, grounding was achieved by connecting the ground terminal of a receptacle to the metal electrical box, whose ground came from the EMT!
We were instructed to replace the receptacles with the orange, isolated ground recepts. and to run a a new, insulated ground conductor (green) back to the distribution panel, at this panel we installed a new bus, isolated from any ground, which in turn was connected using a heavy gauge cable (perhaps #3) back to a new ground bus at the main panel. Still isolated! This bus was then grounded to the same grounding as the main panel. Not at the panel, but at the place where the main panel ground was connected.
The whole idea, was that the grounding formed a tree! From the building ground, the trunk to the main panel. The branches to the service panels and then branched out to all the grounded outlets, as required!
This was done to prevent any current loops where noise might travel.

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Old 02-23-2009, 03:37 PM   #29
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Isolated Ground Receptacle


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When I was employed at the university, I was working under the direction of the Director of Physical Plant. A professional, electrical engineer!
From my experience, an EE typically THINKS he knows as much (and usually more) as the typical construction electrician. This is almost never the case.
An EE is as related to the construction electric trade as a plumber is.






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Originally Posted by Wildie View Post
Previously, grounding was achieved by connecting the ground terminal of a receptacle to the metal electrical box, whose ground came from the EMT!
We were instructed to replace the receptacles with the orange, isolated ground recepts. and to run a a new, insulated ground conductor (green) back to the distribution panel, at this panel we installed a new bus, isolated from any ground, which in turn was connected using a heavy gauge cable (perhaps #3) back to a new ground bus at the main panel. Still isolated! This bus was then grounded to the same grounding as the main panel. Not at the panel, but at the place where the main panel ground was connected.
The whole idea, was that the grounding formed a tree! From the building ground, the trunk to the main panel. The branches to the service panels and then branched out to all the grounded outlets, as required!
This was done to prevent any current loops where noise might travel.
This is TOTALLY different that what you said previously!
You said the grounds were connected to ground rods. NOW you are saying you ran an insulated ground all the way back to the main service equipment and connected there, where just as a coincidence, the grounding electrode conductors are connected as well. The real safety ground in that panel comes from the neutral BOND.
That IS a proper IG installation.
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Old 02-23-2009, 04:11 PM   #30
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Isolated Ground Receptacle


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From my experience, an EE typically THINKS he knows as much (and usually more) as the typical construction electrician. This is almost never the case.
An EE is as related to the construction electric trade as a plumber is.

This is TOTALLY different that what you said previously!
You said the grounds were connected to ground rods. NOW you are saying you ran an insulated ground all the way back to the main service equipment and connected there, where just as a coincidence, the grounding electrode conductors are connected as well. The real safety ground in that panel comes from the neutral BOND.
That IS a proper IG installation.

When the EE is the boss, you follow his direction! Plain and simple. Especially after he has consulted with the Electrical Safety people!

In my initial post, I did insert 'rod' in error! Although, in one instance, this was exactly what I had to do!

" ran the ground from the receptacles back to a ground rod, rather than back to a ground bus in the panel."

I was attempting make a point that any connection to a panel case was to be avoided, and this was what I wanted to emphasize!

I must say, in responding to the OP's post, I would have been more cautious with my words, had I considered, even in my wildest dreams that I would have been responded to with such venom!
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