NEC 517.13, Redundant Grounding Patient Care Spaces

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Shujinko

Shujinko

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I have an installation where a bunch of branch circuits in exam rooms in a clinic were installed with MC Cable, Non-medical grade. The MC cables do not have redundant grounding, they only have a equipment grounding conductor wire. The sheathing or armor are not considered equipment grounding conductors as required by NEC 517.13(A)&(B) I have 2 questions.

1. Are there any code exemptions that allow me to keep the installed MC cable as installed without redundant grounding?
2. Alternatively, Is there anyway I can convert the existing MC Cable to have redundant grounds? Like fishing a bare ground wire down into the armor?

Obviously, I am trying to avoid having to replace all the MC Cable with medical grade MC cable. My Jurisdiction is under NEC 2017. I appreciate all suggestions!
 
Thanks for your responses. I have a twist to this situation. Apparently, the branch circuits for the ground floor exam room receptacles were run underground in PVC. With a hot, neutral, and EGC conductor. If we were to run a second EGC in the PVC can that be considered redundant grounding per 517.13(A)&(B)? Seems like a long shot but has anybody been successful using this strategy? To me it seems like 2 THWN's for the EGC, one connected to the outlet box and the other connected to the receptacle would be a robust equipment grounding scheme. But I would like to hear some other opinions and experiences.
 
Shujinko said:
If we were to run a second EGC in the PVC can that be considered redundant grounding per 517.13(A)&(B)? Seems like a long shot but has anybody been successful using this strategy?
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No, that will not satisfy 517.13(A). NFPA 99 has commentary that explains the metallic sheath covered in 517.13(A) is the primary EGC and the wire type per 517.13(B) is the secondary. It might be worth discussing it with the AHJ though.
 
Two wire type EGCs does not meet the requirements. 517.13(A) requires the metal conduit or cable armor to qualify as an equipment grounding conductor. The wire type EGC required by 517.13(B) is in addition to the raceway grounding conductor.

If you can pull HCF through your PVC, that would meet the requirement. Otherwise, you will be cutting up the concrete or running new circuits overhead.
 
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