Isolated Ground Loads

[powerray98]

Is it permisable to connect air compressors to an isolated ground circuit? And the flip side of this question is, should PC's be connected only to isolated ground circuits> Another part of this is, are the answers given based on standard practice or code requirements? The background on this is that there are mainly 2 types of circuits on a floor, generator backed circuits (red recpticles) and isolated ground circuits (orange recepticles). Don't ask my why but there are very few normal circuits. The customers are plugging some of their PCs into the red recepticles. When the air compressors are plugged into the red recpticles it trips the breaker. PC users are not happy. So compressor users are advised not to use the red plugs and use the orange instead. Is this proper? It doesn't seem like it to me.

 

[Buck Parrish]

Is this in a patient care area? If so all need an isolated ground.
The hall and lobby do not. Unless it is in the building specs.

 

[raider1]

Is this in a patient care area? If so all need an isolated ground.
The hall and lobby do not. Unless it is in the building specs.

I think you are confusing an isolated ground with the "redundant ground" that is required in 517.13.

Chris

 

[raider1]

Is it permisable to connect air compressors to an isolated ground circuit?

Yes, there is no NEC section that prohibits plugging a compressor into an isolated ground receptacle.

Isolated ground circuits are a design choice and not required by the NEC.

Lately I haven't been seeing many isolated ground circuits being installed in new construction.

Chris

 

[Buck Parrish]

I think you are confusing an isolated ground with the "redundant ground" that is required in 517.13.

Chris

Yes , exceeding what is neccessary or it is no longer needed.
Compressors are some times used in health care facilities.
But we don't know where the op is talking about.

 

[powerray98]

Here's the deal. We have a floor that was originally built out to be a computing floor. They've turned it into a print shop. All around the outside wall are red and orange recepticles. Along the inside wall are white recepticles. We are not in a healthcare facility. I've been told by a technician who works on it that the red recepticles are backed up by generator power. The orange recepticles they call "dedicated". Orange recepticles on other office space floors are where the PCs are supposed to be plugged into. I'm assuming that the orange are isolated grounds since that's what internet research indicated orange recepticles are used for. Printshop technicians want to plug into orange recepticles. What I'm hearing is that it is permissable even though it's odd.

 

[suemarkp]

I don't think it matters. Previous management in my building wanted all computer circuits to be isolated ground. Either computers have gotten better, or that wasn't a problem, as we don't have any problems with non-IG circuits for computers.

All the isolated ground does is have its own dedicated insulated ground wire back to the panel. A raceway ground or bare grounding wire could pick up stray currents that may "do things" to computer circuitry.

The compressor won't care one bit whether the ground is isolated or not. But if there are things on those orange circuits that don't like the voltage sags and spikes caused by the compressor cycling, that could be a different issue. Whether its IG or not shouldn't make any difference.