PVC in Patient Areas w/ 2 EGC

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W6SJK

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If the requirement in Art 517 is a redundant ground for Patient Care areas, why can't we use PVC40 or 80 with 2 equipment grounding conductors? Wouldn't that accomplish the intent? Is it also a matter of toxic fumes during a fire in a patient care area vs. other areas where PVC is allowed?

I'm asking because the area is corrosive (salt air).

I've searched and cannot find this addressed before.
 
Two ground wires would not fulfill the requirement. I've been told that because a ground wire and a conduit terminate differently, the failure of a ground wire(s) bus would not necessarily remove the ground, since the conduit would be more or less continuous.

Jim T
 
I don't have the NEC electronically* or I would quote 517 wiring methods. PVC is not one of them. Reason: because they said so.

*It is part of the State Statues and should therefore be available to all residents. my $0.02 1/2.
 
Here's part of the code text:

517.13 Grounding of Receptacles and Fixed Electric Equipment in Patient Care Areas
Wiring in patient care areas shall comply with 517.13(A) and 517.13(B).
(A) Wiring Methods All branch circuits serving patient care areas shall be provided with a ground path for fault current by installation in a metal raceway system, or a cable having a metallic armor or sheath assembly. The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding return path in accordance with 250.118.
 
Thanks but I already knew the NEC verbage. :) The question was WHY? What is the intent?

pete m. said:
Here's part of the code text:

517.13 Grounding of Receptacles and Fixed Electric Equipment in Patient Care Areas
Wiring in patient care areas shall comply with 517.13(A) and 517.13(B).
(A) Wiring Methods All branch circuits serving patient care areas shall be provided with a ground path for fault current by installation in a metal raceway system, or a cable having a metallic armor or sheath assembly. The metal raceway system, or metallic cable armor, or sheath assembly shall itself qualify as an equipment grounding return path in accordance with 250.118.
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It isn't due to toxic fumes (although that may be addressed in other parts of the code). It's a way to make sure equipment is grounded. And I think the code making panels have stated that two EGC's does not provide the same safety as one EGC and one ground wire.

If the electrician forgets to terminate one EGC, he is going to forget to terminate them both. If one ground gets cut, chances are both will get cut. If salt water corrodes one EGC termination, it will probably corrode another termination. The conduit, on the other hand, is less likely to be compromised. Especially if it is grounded in several places by being clamped to a metal structure every so often.

Buy the way - what part of a hospital would have salt air in it?? Are you saying some type of treatment uses salt air, or is it just located near the ocean?
 
steve66 said:
By the way - what part of a hospital would have salt air in it?? Are you saying some type of treatment uses salt air, or is it just located near the ocean?
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It's near the ocean... thanks.
 
Sparkie001, they need to close the windows. :wink: I have worked in a number of hospitals in FL and never had abnormal corrosion problems inside the buildings. :)

If you have access to the 2002 NFPA 99 read Annex A 4.3.3.1.3 for the NFPA's reasoning for the metallic raceway.

You will see that the "Insulated Conductor" is actually the "secondary" fault clearing path and the metallic raceway is the "primary" fault clearing path in "Patient Care Vicinities" this is apparent if you read Exception No 2 of 517.13(B)

Roger
 
steve66 said:
If the electrician forgets to terminate one EGC, he is going to forget to terminate them both. If one ground gets cut, chances are both will get cut. If salt water corrodes one EGC termination, it will probably corrode another termination. The conduit, on the other hand, is less likely to be compromised.
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This is so interesting, considering the number of members who in other threads have suggested that conduit is unreliable as a sole EGC pathway, and should always be augmented with a separate EGC wire.
 
Larry:

I also agree with that. I think conduit by itself is pretty bad - and worse in a nonconducting structure. A wire is good, but a wire and conduit is best.

Sparkie001:

I think you are trying to find an excuse not to use metal conduit. I agree with Roger, the salt shouldn't be a problem -although since I live in Illinois, I can't really say I have seen installations exposed to salt air :)
 
If you goofed and didn't bid it in then just bend over.Yes it is costly but no cheap way out.If its under a slap look at threadless fittings and rigid.No matter how we debate this your going to be running steel conduit.
 
steve66 said:
Sparkie001:

I think you are trying to find an excuse not to use metal conduit. I agree with Roger, the salt shouldn't be a problem -although since I live in Illinois, I can't really say I have seen installations exposed to salt air :)
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It's actually the owner that wants to use PVC. Thanks for the replies.
 
Then all you have to do is tell them "no way, no how" :)

They are not the first ones that have wanted to use PVC and two grounds. I think the PVC conduit manufacturers even tried to get the NEC to approve two grounds. That suggestion was shot down. I think I saw this somewhere on this forum. Someone actually posted the Code Making Panels response to a proposal to allow PVC with 2 grounds.


Steve
 
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