NEC Art 517.14

[roger]

NEC does allow an EGC to be installed by itself in a raceway. In fact #6 and smaller are required to be protected 250.120C

As #10 is stated as the min size allowed I believe that 517.14 implies that the EGC should be sized per 250.122. Perhaps sized based on the largest OCP device since not installed with a branch circuit of feeder??

517.13 mandates the raceway be metal not necessarily ferrous, and meet the requirements of 250.118 to be considered an EGC

Yes, the raceway is required to be bonded by an approved method for your particular set of circumstances.

The conductor in 517.14 is simply for equipotential of the different systems serving the room, it serves no other purpose really. The EGC's are satisfying 250 and 517 fault clearing purposes. You can read the equipotential requirements in chapter 6 of NFPA 99

Roger

 

[roger]

The conductor in 517.14 is simply for equipotential of the different systems serving the room, it serves no other purpose really. The EGC's are satisfying 250 and 517 fault clearing purposes. You can read the equipotential requirements in chapter 6 of NFPA 99

Roger

In earlier cycles of NFPA 99 it was chapter 4

Roger

 

[LIM]

While we're discussing this section, can someone explain why the second sentence is in there? It seems to me that would be covered by the first sentence.

The reason for the second sentence is due to the fact that at some locations in the hospital you may have two essential branch panel boards served from separate transfer switches. This is the case when some hospitals use a second critical branch transfer switch to serve as the "normal" power in ORs and such. It also reinforces the fact that any equipment, life safety, or critical branch panel boards serving the same patient care area would need to be bonded.

 

[Smart $]

The reason for the second sentence is due to the fact that at some locations in the hospital you may have two essential branch panel boards served from separate transfer switches. This is the case when some hospitals use a second critical branch transfer switch to serve as the "normal" power in ORs and such. It also reinforces the fact that any equipment, life safety, or critical branch panel boards serving the same patient care area would need to be bonded.

Still seems redundant...

I suppose someone may interpret, "The equipment grounding terminal buses of the normal and essential branch-circuit panelboards serving the same individual patient care vicinity..." as meaning only normal and essential panelboards are to be bonded rather than all normal and essential panelboards serving the same area.

 

[roger]

Still seems redundant...

I suppose someone may interpret, "The equipment grounding terminal buses of the normal and essential branch-circuit panelboards serving the same individual patient care vicinity..." as meaning only normal and essential panelboards are to be bonded rather than all normal and essential panelboards serving the same area.

This was kind of the reason for a 1993 ROP

17-36- (517-14): Accept Secretary's Note: The Correlating Committee directs the Panel to change "may" to "shall be permitted to" in the second line of the . Recommendation. SUBMITI'ER: Phillip W. Knight, West Palm Beach, FL RECOMMENDATION: Where more than two (2) panels serve the same location, the grounding conductor shall be continuous from panel to panel, but may be broken in order to terminate on the ground bus in each panel. SUBSTANTIATION: The Code addresses a two (2) panel installation. We now have installations which allow multiple panels to feed one (1) patient location. The Code would require the grounding conductor to be unbroken as it passed through a middle panel.

PANEL ACTION: Accept
VOTE ON PANEL ACTION: Unanimously Affirmative

Roger