IG receptacle

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nizak

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How do you avoid continuity between the grounding slot on an IG receptacle and the metallic box and conduit when the service neutral is bonded to the enclosure? This may sound like a dumb question but please bear with me. Thanks
 
You don't they are all bonded together in the panel. You did install an insulated ground?
 
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I'm not sure what you mean by grounding slot on recept but the metal yoke is already isolated from the grounding pin on IG recept's.
 
The conduit is the grounding means for the box and an insulated conductor is run inside the conduit and connected to the grounding screw on the IG recp and not to the box.
 
Aren't you negating the whole purpose of the IG recep if you still have continuity between the grounding pin and the conduit? I've had computer techs tell me that "electrical noise" will be present if the two are bonded together. Thanks.
 
Make sure you have an isolated ground receptacle, connect an insulated ground conductor only to ground screw on receptacle, run it back to isolated ground bus in panel.
 
nizak said:
Aren't you negating the whole purpose of the IG recep if you still have continuity between the grounding pin and the conduit? I've had computer techs tell me that "electrical noise" will be present if the two are bonded together. Thanks.
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No, the Code requires the two to be bonded together. It wouldn't be a ground if it didn't have any continuity to ground.

Steve
 
nizak said:
Aren't you negating the whole purpose of the IG recep if you still have continuity between the grounding pin and the conduit? I've had computer techs tell me that "electrical noise" will be present if the two are bonded together. Thanks.
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Welcome. :D The whole idea is that they are bonded together at the service, and not at the end of the branch circuit. Think about why we don't use a single wire for both the grounded and grounding conductors, even though they eventually do connect.

Any current (that should theoretically not exist) traveling through a branch circuit's EGC and/or conduit will place all of the enclosures at a potential other than absolute zero. That's why 3-wire receptacles on a 2-wire circuit protected by a GFCI should never have any EGC's made up.

The idea is to keep the chassis of electronic equipment as close to absolute zero (the earth and/or service neutral) as possible. Unwanted currents are noise to sensitive electronic circuits. They can cause desired-signal corruption or supression and even cause component damage.

Electrically speaking, you treat the insulated green IG conductor as if it were a line conductor; completely insulated and isolated. They can be spliced in any sub-panel, and run alongside the feeders, back to the main disconnect, where the neutral/EGC bond is made.
 
Here's a picture I took at a service call of how one installer took care of three isolated ground receptacles:

isolatedgroundviolation.jpg
 
Wish I had a pic of it, but I run across a "true" isolated ground in a big box computer room. The run all of the isolated grounds to an insulated ground bar, but did not connect any ground at all to that bar. Can't get much more isolated than that!:rolleyes:
 
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