517.13 vs 517.16

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chris kennedy

chris kennedy

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Location
Miami Fla.
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60 yr old tool twisting electrician
I have a new EE that has speced IG recepticals for patient care areas. My first thought was you can't do that, it's a voilation of 517.13.

Then I looked around and found this.

517.10 Applicability.
(A) Applicability. Part II shall apply to patient care areas of all health care facilities.

517.16 Receptacles with Insulated Grounding Terminals.
Receptacles with insulated grounding terminals, as permitted in 250.146(D), shall be identified; such identification shall be visible after installation.
FPN: Caution is important in specifying such a system with receptacles having insulated grounding terminals, since the grounding impedance is controlled only by the equipment grounding conductors and does not benefit functionally from any parallel grounding paths. This type of installation is typically used where a reduction of electrical noise (electromagnetic interference) is necessary and parallel grounding paths are to be avoided.
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So I'm a little confused as to how using an IG rec doesn't violate 517.13.
 
I asked this question directly to Mark Ode at the 2007 Ellis Canady IAEI meeting and he said in essence that 517.16 is not meant for patient care vicinities.

Regardless, unless there is an exception to 517.13(A), IG receptacles can not be used in these areas anyways, 517.16 is not granting permission to ignore 517.13(A) and if isolation is needed, a small isolating transformer can be wheeled in on a cart as part of the equipment.

IOW's 517.16 is useless IMO.

Roger
 
If the engineer wants the circuits isolated, I don't see where that is impossible to do. 517.13 can be accomplished by providing an isolated raceway ground in addition to an isolated/insulated ground, providing for both A and B, and also meeting 517.16. It might not be practical, but if there is some need for that it seems do-able without a dilemma (?)
 
nakulak said:
If the engineer wants the circuits isolated, I don't see where that is impossible to do. 517.13 can be accomplished by providing an isolated raceway ground in addition to an isolated/insulated ground, providing for both A and B, and also meeting 517.16. It might not be practical, but if there is some need for that it seems do-able without a dilemma (?)
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I disagree, I read it as fault current needs a redundant path meaning the wiring method and the insulated ground.

The branch circuit wiring method used in these areas is one component of a two-part redundant grounding scheme unique to patient care areas. The second component in this approach is the separate insulated copper conductor required by 517.13(B). Therefore, the metal raceway or metal cable armor or sheath must qualify as an equipment grounding conductor in accordance with 250.118, independent of any separate wire-type equipment grounding conductor.
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Chris,..I found this thought you would be interested

Question:
Subject: Isolated ground receptacle in Patient Care Area
Charlie,
When installing isolated grounding receptacles in areas used for patient care in health care facilities, how many equipment grounding conductors should be provided with the circuit? I was told that 3 separate equipment grounding conductor paths are required.
Thanks,
John D.


Answer:
Hi John

First let?s look at two pertinent sections.
517.13(A) requires an effective ground-fault current path by installation of the circuit conductors in a metal raceway or a cable having a metal armor that qualifies as an equipment-grounding conductor
517.13(B) requires the grounding terminals of all receptacles to be connected to an insulated copper equipment-grounding conductor.

The equipment-grounding conductor must be installed in a metal raceway or be a part of a listed cable having a metallic armor.
Those two sections indicate what could be called a redundant grounding system. What we must provide is an insulated copper equipment grounding conductor (517.13(A) and it must be installed in a metal raceway or be part of a listed cable having a metallic armor (517.13(B). The two grounding methods are required to assure an effective grounding path is present at all times.

However, if the receptacle being connected is a receptacle with insulated grounding terminals then 240.146(D) requires for isolated ground receptacles, where the receptacle grounding terminal is purposely insulated from the receptacle mounting means, that the receptacle grounding terminal must be connected to an insulated equipment-grounding conductor which is permitted to be run without a connection to the panelboard grounding terminal so as to terminate at the equipment grounding terminal of the derived system or service.
Based on the above, yes three separate ground-fault paths must be provided where isolated ground receptacles are installed.
However remember that, when specifying isolated ground receptacles you do not have the parallel or redundant ground required by 517.13(A) & (B) protecting the equipment fed by the receptacle (517.16 FPN).

Section: 517.13(A), 517.13(B),240.146(D), 517.16 FPN Source: Charlie Trout

ANSWERS: Answers are the author?s opinions and do not represent formal interpretations of the National Electrical Code.

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ABOUT THE AUTHOR: Charlie Trout is a nationally-known NEC expert and author. He served on three different National Electrical Code-Making Panels and is past chairman of CMP-12. He is also a member of the NECA Codes & Standards Committee. In 2006 Charlie Trout won the prestigious Coggeshall Award, given to recognize outstanding contributions to the electrical contracting industry in the technical and training area.
 
To bad Charlie isn't part of CMP 15, maybe he wouldn't have missed the reason for the requirements of 517.13(A) and (B)

Sorry, but adding another EGC attached only to another EGC is absolutely stupid and does nothing as far a redundant fault clearing path for the device or equipment connected to the branch circuit.

The metalic raceway is the primary EGC in these installations and the insulated conductor is the secondary


Roger
 
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roger said:
Sorry, but adding another EGC attached only to another EGC is absolutely stupid and does nothing as far a redundant fault clearing path for the device or equipment connected to the branch circuit.

The metalic raceway is the primary EGC in these installations and the insulated conductor is the secondary


Roger
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Agreed, run 13 EGC's to the box. If only one is terminated on the IG device, where is the redundancy?
 
I don't think he missed it ,..
However remember that, when specifying isolated ground receptacles you do not have the parallel or redundant ground required by 517.13(A) & (B) protecting the equipment fed by the receptacle (517.16 FPN).
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M.D. where is the wording in 517.16 that gives permission to ignore the requirements (note the word requirement) of 517.13(A) and (B)?

I would think that if pains were taken to provide two exceptions to 517.13(B) for switch plates and luminaires above 7.5 feet, that there would certainly be an exception in 517.13(A) for an item like 517.16.

Roger
 
run 13 EGC's to the box. If only one is terminated on the IG device, where is the redundancy?
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I can't help but ask. :)


How many EGC are in the cord from the receptacle to the utilization equipment?

I'll leave now........:grin:
 
iwire said:
How many EGC are in the cord from the receptacle to the utilization equipment?
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Frankly Mr. Codeman I'm shocked at this post. Please read the code as it is written. I have to pass an inspection here.:grin:
 
iwire said:
I can't help but ask. :)


How many EGC are in the cord from the receptacle to the utilization equipment?

I'll leave now........:grin:
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Don't leave Bob ;). What happens beyond the device is not our concern.

This means we don't care if a piece of equipment in the room has one, two, or even no EGC in it's cord, and we don't care if a sensitive piece of equipment in the patient care vicinity has a problem with noise from the required bonding of 517.13. :wink:


Roger
 
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Did the engineer only stress the code, or did he show you how to apply it ?

I thought it was individual branch circuits in this case.
 
When I read this thread I am thinking ( jokingly ) you need a 4-wire 125 volt receptacle 1-hot, 1-neutral, 1-isolated ground, 1-redundant ground. Now my head hurts.
 
cadpoint said:
Did the engineer only stress the code, or did he show you how to apply it ?
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He gave me a detail showing 2 EGC leaving the conduit and entering the box. One goes to the device and the other to the box. But that doesn't meet this.

Therefore, the metal raceway or metal cable armor or sheath must qualify as an equipment grounding conductor in accordance with 250.118, independent of any separate wire-type equipment grounding conductor.
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I'll scan the detail but its not very clear.
 
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