Isolated Ground?

[NorthwestPV]

A lot of our jobs call for isolated ground receptacles (not patient care). The issue I have is on the isolated ground receptacles we are using, the yoke has continuity to the receptacle ground. If you ground the box with the equipment ground, it makes the entire isolated grounding system no longer isolated. The circuiting is almost always in EMT. If the receptacle was recessed, I could see using a plastic mudring. What do you do if it is installed in an industrial cover? I have seen hospital grade receptacles with two separate grounds but my employer does not want to pay the cost difference for these. I was wondering if one could use a PVC fitting in the conduit run to isolate the grounding an that circuit? Is there another option?

 

[ActionDave]

A lot of our jobs call for isolated ground receptacles (not patient care). The issue I have is on the isolated ground receptacles we are using, the yoke has continuity to the receptacle ground.....

There is no possible way you are installing isolated ground receptacles then.

 

[GoldDigger]

Some people (even those who write specifications) do not understand the distinction between isolated ground and redundant ground.

 

[roger]

Is there another option?

Yes, buy Isolated Ground Receptacles, they will have a green "Triangle" on them not to be confused with a green "Dot".


Roger

 

[Pharon]

Some people (even those who write specifications) do not understand the distinction between isolated ground and redundant ground.

I have never heard of someone specifying a "redundant" ground. What's the purpose of that, and how is it different from an isolated ground?

Yes, buy Isolated Ground Receptacles, they will have a green "Triangle" on them not to be confused with a green "Dot".

And typically they are orange in color.

 

[ceb58]

I have seen hospital grade receptacles with two separate grounds but my employer does not want to pay the cost difference for these

.

And there lies your problem. Inform him that what you are doing doesn't meet what the spec. sheet calls for and put the ball back in his corner.

 

[kingpb]

.

And there lies your problem. Inform him that what you are doing doesn't meet what the spec. sheet calls for and put the ball back in his corner.

406.3(D) requires orange triangle on face of receptacle.
517.16 Isolated ground Recep is not allowed within patient care vicinity.

Green dot, means hospital grade receptacle. Interesting though that the outlet can be orange with a green triangle, makes sense because it's easier to see, but technically doesn't meet code.

 

[don_resqcapt19]

I have never heard of someone specifying a "redundant" ground. What's the purpose of that, and how is it different from an isolated ground?

That is what is required by the code for patient care areas. The circuit must use a wiring method where the metallic cable jacket or the metallic conduit is a code compliant EGC along with an EGC of the wire type.

And typically they are orange in color.

Yes, I though so too, but after looking at Roger's post, I found a number with a green triangle in online pictures of isolated ground receptacles. That being said, the UL Guide Information for Receptacles for Plugs and Attachment Plugs (RTRT) says the following.

Isolated Ground Receptacles — Grounding-type receptacles in which the grounding terminals are purposely insulated from the mounting means of receptacles and associated metal cover plates as permitted by Section 250.146(D) (formerly Exception No. 4 to Section 250-74) of the NEC are so identified by an orange triangle marked on the face of the receptacle.

 

[NorthwestPV]

The receptacles we are using are orange with a green triangle on the face. I was shocked when learning that the yoke and receptacle ground were tied together. In fact I lost a bet over it.

 

[GoldDigger]

The receptacles we are using are orange with a green triangle on the face. I was shocked when learning that the yoke and receptacle ground were tied together. In fact I lost a bet over it.

That certainly sounds like they are not actually isolated ground. So apparently the orange rather than green triangle really makes a difference. Look in the Hubbell catalog to see the various options in their line and how they mark them.
If the receptacles you are looking at actually claim to be isolated ground, then they are in violation of the UL spec for that designation and need to be returned/rejected ASAP.

 

[ActionDave]

The receptacles we are using are orange with a green triangle on the face. I was shocked when learning that the yoke and receptacle ground were tied together. In fact I lost a bet over it.

Did you check them in the box or installed on a circuit.

 

[roger]

The receptacles we are using are orange with a green triangle on the face. I was shocked when learning that the yoke and receptacle ground were tied together. In fact I lost a bet over it.

Please post the manufacturer and model number of the receptacles you are using.

Roger

 

[GoldDigger]

Look at 406.3(D) [2014] for information.
AFAIK, except as called out in the engineering specs for the contract, isolated ground receptacles are not required by the NEC anywhere in hospitals or related facilities, and where Hospital Grade is required that may be inconsistent with use of isolated ground!
Isolated circuits (essentially branch transformers) may be required for some very specialized areas, but that is not the same as isolated ground.
Some plans call for isolated ground for data and/or analog interface equipment, despite the fact that there is very little evidence that it improves things IF the correct shield and ground isolation between equipment has been done.