701.12(E)

[charlie b]

701.12 says that, in addition to the normal supply of electricity, we are permitted to use one or more of the sources that are described in usb paragraphs (1) through (F) as the alternate source for the Legally Required Standby system. Item (E) is the "tap ahead of the main." I am reviewing a design that uses a tap ahead of the main, and no other source, as the supply to the LRS panel. Is that allowed?

 

[ron]

I've bolded the important part.


(E) Connection Ahead of Service Disconnecting Means.
Where acceptable to the authority having jurisdiction, connections located ahead of and not within the same cabinet, enclosure, or vertical switchboard section as the service disconnecting means shall be permitted. The legally required standby service shall be sufficiently separated from the normal main service disconnecting means to minimize simultaneous interruption of supply through an occurrence within the building or groups of buildings served.

I have not had luck getting the AHJ to do this

 

[steve66]

Does this include exit and emergency lighting, or are they on a separate "emergency system"?

I'm not sure which section they fall under (700 or 701), and both sections talk about unit equipment.

The reason I mention it is that the International Building Code would require a separate source of power for the exit and emergency lighting. I don't think a tap ahead of the main would comply.

 

[cowboyjwc]

Does this include exit and emergency lighting, or are they on a separate "emergency system"?

I'm not sure which section they fall under (700 or 701), and both sections talk about unit equipment.

The reason I mention it is that the International Building Code would require a separate source of power for the exit and emergency lighting. I don't think a tap ahead of the main would comply.

I would agree. I bet that 9 out of 10 times that the power goes out to a building, it is a utility issue and not an issue with the buildings equipment, so a tap ahead of the main would serve no purpose.

 

[charlie b]

Steve, we are dealing with 701 only. No emergency equipment is being shown as powered from the electrical distribution system. So I infer they plan to use batteries for the egress lights.

Ron, I saw the "with the AHJ's blessing" part. But you need to look further upstream. You don't get to sub paragraph (E) without first encountering the text of 701.12. The relevant words are, "The supply system for emergency purposes, in addition to the normal services to the building . . . shall be one or more of the types of systems described in 701.12(A) through 701.12(E)." So I don't see how using just a tap ahead of the main as the only source can satisfy this requirement.

On the other hand, I also don't see the value in using a feeder from the normal distribution system, using a feeder tapped ahead of the main, and using an ATS to switch between the two, as having any value. As John pointed out, odds are that they both go down together. That calls into question the purpose of 701.12(E) in the first place.