Healthcare subpanel - feeder cable or conduit?

[buzzbar]

Hi all,

We're in the process of installing (3) 200A sub-panels, fed from an 800A main distribution panel (all 120/208V 3-phase). This is for a fairly large healthcare clinic, and all three sub panels will be located throughout the clinic (all with HCF MC cable branch circuits fed from them).

I would like to feed each of these panels with 250 AL XHHW feeder cable (Stabiloy cable). I have two questions:

1) This cable has an UNinsulated equipment ground wire, is this okay?

2) Would this cable be okay to feed a sub-panel in a healthcare environment?

FYI: there are NO critical care areas, just a basic doctor's office, physical therapy.

Thanks in advance!

Andy

 

[jeremy.zinkofsky]

517.13(B)(1) requires an insulated continuos copper equipment ground for branch circuits.
517.14 requires the same for Panleboard bonding.

Don't see how you can meet that requirement when you will be supplying each panelboard with an uninsulated Aluminum conductor to bond to.

 

[buzzbar]

I realize that the branch circuits need an insulated ground, that's not the issue.

Also, 517.14 refers to 'essential' branch circuit panelboards, which our panelboards are not. Looking at the definitions in 517, 'essential' panelboards are ones that are backed up by an alternate power source (i.e. generator). Again, our panels are not backed up by generators.

Anyone else have any thoughts on this?

 

[jeremy.zinkofsky]

I realize that the branch circuits need an insulated ground, that's not the issue.

Also, 517.14 refers to 'essential' branch circuit panelboards, which our panelboards are not. Looking at the definitions in 517, 'essential' panelboards are ones that are backed up by an alternate power source (i.e. generator). Again, our panels are not backed up by generators.

Anyone else have any thoughts on this?

Actually, 517.14 refers to both "normal" and "essential" panelboards and falls under 517-II which applies to the patient care space of all health care facilities. It is requiring you to bond both normal and essential together when they serve the same patient care vicinity. If you are required to bond an essential panel to a normal panel with insulated copper, then it would make sense that the normal panel already has an insulated copper EGC.

517 does not say that you cannot use Aluminum conductors to feed you subpanels, it references Chapters 1 - 4 to be used for the wiring methods. The point I was trying to make is that an inspector may want to see a "continuous copper" low impedance path for the EGC's.

 

[buzzbar]

517.14 refers to bonding 'essential' panels WITH 'normal' panels. I am NOT dealing with any 'essential' panels, so I don't see how this is relevant to my question.

Also, I am not asking if I can use aluminum wire, my question is in regards to the NON-insulated ground wire in the FEEDER cable.

I'll ask again:

Is it permissible to use feeder cable with an UNinsulated ground wire that feeds a subpanel that will have patient care area "redundant" ground branch circuits?

I appreciate any help.

Thanks!

 

[roger]

2) Would this cable be okay to feed a sub-panel in a healthcare environment?



Andy

Yes, it is fine, feeders do not have the same requirement as branch circuits.

Roger

 

[buzzbar]

Thank you Roger. I was thinking the same thing. I'm also waiting for an answer from my AHJ, but wanted to get opinions. Andy