hospital grade mc

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n84jrnation

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I am doing a children's doctors office. I have been told to run hospital grade mc inside the rooms and change over to regular mc in the halls going back to the panel. Is this correct or do i need to change to emt then go back to the panel. and i am not sure of the theory behind the redundant if you could elaborate.
 
517.13 requires the branch circuit to provide redundant grounding.
By definition a branch circuit originates at the overcurrent device so your 250.118 acceptable raceway would need to extend back to the panel with the branch circuit overcurrent device, IMO.
 
augie47 said:
517.13 requires the branch circuit to provide redundant grounding.
By definition a branch circuit originates at the overcurrent device so your 250.118 acceptable raceway would need to extend back to the panel with the branch circuit overcurrent device, IMO.
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I agree with Gus.
 
The last 2 companies I worked for only ran HGMC in the rooms required then changed over to MC in the halls and back to the panels. Regular MC is cheaper, less heavy/rigid, and easier to work with so the labor and material cost on larger jobs makes the change over worth it.


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teufelhounden91 said:
The last 2 companies I worked for only ran HGMC in the rooms required then changed over to MC in the halls and back to the panels. Regular MC is cheaper, less heavy/rigid, and easier to work with so the labor and material cost on larger jobs makes the change over worth it.
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And if they did that it is a direct code violtion.

You can supply hallway lighting with regular MC but not the areas requiring redundant grounding.
 
augie47 said:
517.13 requires the branch circuit to provide redundant grounding.
By definition a branch circuit originates at the overcurrent device so your 250.118 acceptable raceway would need to extend back to the panel with the branch circuit overcurrent device, IMO.
Click to expand...

I will attempt to further explain what Gus said.

NEC doesn't use the term redundant grounding - that is more of a field slang term used to describe what is required by 517.13.

What it does require is much more wordy.

We must use a wiring method that in itself qualifies as an equipment grounding conductor such as metal raceways or metal sheathed cables (but standard MC doesn't qualify, the type with the bare aluminum bond wire inside does).

We must also use an insulated wire type equipment grounding conductor. By having requirement to have two types of equipment grounding used we get the "redundant" grounding as it is often called.

This applies to branch circuits, and the entire branch circuit not just what is in the patient vicinity, but does not apply to feeders.
 
Mind blown. My previous boss said the egc in the EMT in the hallway and the EMT itself were considered redundant once changed over from HGMC. Christ that's a serious mistake. He said the mc cable was a valid means for grounding too though I now know that's not the case.


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teufelhounden91 said:
My previous boss said the egc in the EMT in the hallway and the EMT itself were considered redundant once changed over from HGMC.
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Yes that is correct and a compliant installation.


It sounded like you said you were changing over to regular MC from HGMC once you got in the hall. That would be a violtion.
 
:ashamed: the company before that did that too :/ he would have us run 12/4 mc homeruns to jboxes above the rooms then split down with HGMC to the plugs in the room.


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roger said:
Doesn't matter if it did, it still wouldn't comply with 517.13(A).

FWIW, the insulated wire type EGC is secondary and the raceway is the primary EGC, the wire EGC is even allowed to be omitted in Exception No 2 of 517.13(B) but the raceway has to be a recognized EGC per 250.118

Roger
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ty for the clarifications
 
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