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-   -   Isolated Ground Receptacle (http://www.diychatroom.com/f18/isolated-ground-receptacle-38890/)

Bocolo 02-22-2009 09:20 AM

Isolated Ground Receptacle
 
Hello,
Would a receptacle installed at the end of a home run from the panel be considered an isolated ground receptacle?
How would you wire an isolated ground receptacle in a plastic gang box if the above is not an isolated receptacle?
I take it that for this to be an isolated receptacle you can only install one receptacle on this circuit, otherwise you would need to run 14/3 cable and reidentify the red as ground and use the bare for the ground on the other receptacles. Is this correct? Thanks for your time and input.

joed 02-22-2009 09:47 AM

Isolated ground is not a concern in home environment. One recpetalce at the end of a home is about a close you get to isolated.

Bocolo 02-22-2009 09:59 AM

Thanks for the input and your time. I was thinking that maybe I should put my computer equipment and flatscreen tv's on isolated grounds. Thanks again.

Wildie 02-22-2009 10:18 AM

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!

chris75 02-22-2009 10:31 AM

Quote:

Originally Posted by wildie (Post 234534)
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!


This is completly against code !!! And could kill someone. The grounding pin on a receptacle does not go to the planet EARTH... Its bonded to the earth, but the EARTH will not clear a fault and open the over current protection device.

chris75 02-22-2009 10:32 AM

If you want a IG setup using NM style wiring, the easy way to accomplish this is just run homeruns from the receptacle back to the panel and use plastic boxes. Its the exact same thing. Absolutely useless IMO, but knock yourself out.

Bocolo 02-22-2009 10:41 AM

Thanks for the input and your time. I have decided not to go with the isolated ground option. If they are useless or not necessary in residential applications then why bother. Thanks again.

InPhase277 02-22-2009 10:47 AM

Quote:

Originally Posted by Bocolo (Post 234555)
Thanks for the input and your time. I have decided not to go with the isolated ground option. If they are useless or not necessary in residential applications then why bother. Thanks again.

The point is, a dedicated circuit, with a receptacle in a plastic box IS an isolated ground.

chris75 02-22-2009 10:50 AM

Quote:

Originally Posted by InPhase277 (Post 234560)
The point is, a dedicated circuit, with a receptacle in a plastic box IS an isolated ground.

Correct. you just have to install regular receptacles. not IG receptacles.

Bocolo 02-22-2009 10:54 AM

Thanks again. That makes it a lot clearer.

Wildie 02-22-2009 10:59 AM

Quote:

Originally Posted by chris75 (Post 234543)
This is completly against code !!! And could kill someone. The grounding pin on a receptacle does not go to the planet EARTH... Its bonded to the earth, but the EARTH will not clear a fault and open the over current protection device.

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?

chris75 02-22-2009 11:36 AM

Quote:

Originally Posted by Wildie (Post 234570)
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?

:whistling2: Um... lost for words on this... The earth will never clear a fault, use ohms law to see why...


lets use this example, I'm just going to say the earth is 25 ohms, and lets say we use 120v, E= IxR

E/R = 120v/25 ohms = 4.8 amps, You wanna tell me how a ground fault using the earth is EVER going to open a over current device?


Here is PIC of the CORRECT way to IG receptacles...

http://ecmweb.com/power_quality/808ecmPQCfig1.jpg

Picture of ground fault wired the correct way
http://ecmweb.com/power_quality/808ecmPQCfig2.jpg



Picture of incorrect way
http://ecmweb.com/power_quality/808ecmPQCfig4.jpg

Picture of Ground Fault Wired Incorrect Way
http://ecmweb.com/power_quality/808ecmPQCfig5.jpg
Here is a good article for your enjoyment.
http://ecmweb.com/power_quality/elec..._ig/index.html

joed 02-22-2009 01:12 PM

Quote:

Originally Posted by Wildie (Post 234570)
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?

I don't know where you work in Ontario or if you have your work inspected but it is not correct. The ground rod is only there for lightning potection. It serves no electrical path.
When you ran your universty grounds back to a ground rod that ground rod was connected the service entrance equipment. It was not a separate ground.

Wildie 02-22-2009 04:18 PM

Quote:

Originally Posted by joed (Post 234687)
I don't know where you work in Ontario or if you have your work inspected but it is not correct. The ground rod is only there for lightning potection. It serves no electrical path.
When you ran your universty grounds back to a ground rod that ground rod was connected the service entrance equipment. It was not a separate ground.

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!

rgsgww 02-22-2009 04:27 PM

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:laughing:

I'll find it if any of you want to see the violation.


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