Question 73 from Mike Holts Book

[Enriquez]

The ______ branch loads served by the generating equipment cannot be automatically shed upon generating equipment overloading?
(a) emergency (b) equpiment (c) life safety (d) none of these
Which of these is the answer and where in the code is it found?

 

[charlie b]

It is customary for the person posting such a question to give your answer first, or at least to tell us where you have looked and what you have tried to do, to get the answer yourself. We don't do homework assignments for anyone.

 

[electricalperson]

what mike holt book is it? nec prep?

 

[charlie b]

We seem to be having some difficulty with the forum posting process. Here is the OP's take on the problem, as forwarded to me via PM:

My answer is (a) emergency based on article 517, but I'm not sure. I can't seem to find a definite either way. The only other thing I come up with is (d) none of these.........due to my lack of a definite answer.

I don't have the NEC handy to confirm an actual article citation. But I think his answer is correct, from just reading the question in context. I, for one, would not want a load that is actually classified as "emergency" to be included in the load shedding scheme.

 

[jumper]

Based upon 700.5 (b) in 05 I would say (a).

 

[infinity]

Based upon 700.5 (b) in 05 I would say (a).

This is from the 2008:

700.5 Capacity.
(B) Selective Load Pickup, Load Shedding, and Peak Load Shaving. The alternate power source shall be permitted to supply emergency, legally required standby, and optional standby system loads where the source has adequate capacity or where automatic selective load pickup and load shedding is provided as needed to ensure adequate power to (1) the emergency circuits, (2) the legally required standby circuits, and (3) the optional standby circuits, in that order of priority. The alternate power source shall be permitted to be used for peak load shaving, provided these conditions are met.
Peak load shaving operation shall be permitted for satisfying the test requirement of 700.4(B), provided all other conditions of 700.4 are met.
A portable or temporary alternate source shall be available whenever the emergency generator is out of service for major maintenance or repair.

 

[jumper]

:-? Are you saying I got it wrong?

 

[don_resqcapt19]

The only place the code uses the word "branch" in association with loads is in Article 517 where we have the life safety, critical and equipment branch loads on the essential electrical system. The life safety and critical branches make up the emergency system. I would say that (a) is the correct answer.

 

[jumper]

The only place the code uses the word "branch" in association with loads is in Article 517 where we have the life safety, critical and equipment branch loads on the essential electrical system. The life safety and critical branches make up the emergency system. I would say that (a) is the correct answer.

Yes,517.31, 05 code, leads to 700.5 (b) or am I incorrect. Just trying to learn. If i am incorrect please advise. The shedding of loads is defined in order according to 700.5(b)) or am I in error.

 

[Smart $]

The only place the code uses the word "branch" in association with loads is in Article 517 where we have the life safety, critical and equipment branch loads on the essential electrical system. The life safety and critical branches make up the emergency system. I would say that (a) is the correct answer.

Hmmm... to answer "a" would then seemingly permit shedding of "life safety". IMO, "life safety" should never be shed.

 

[wirebender]

I vote "c" because of the wording.
"Life safety" is the only one that can be completed with "branch".

AFAIK, the NEC does not mention equipment branch, only equipment branch circuits.
Same with emergency.
NEC does refer to life safety branch and critical branch.

But I could be wrong.

 

[don_resqcapt19]

Hmmm... to answer "a" would then seemingly permit shedding of "life safety". IMO, "life safety" should never be shed.

The life safety and critical branches make up the "emergency system" for an Article 517 installation. That being said, I think that wirebender has it correct as the term "life safety" is the only one of the answers that has the word "branch" as the next word in the code book.

 

[don_resqcapt19]

This is a confusing question. Taking another look at 517.30(B)(5) there is no provision that would permit the shedding of any of the loads listed in the question. The loads listed there are all required loads for an Article 517 installation.
Yes, I know that I have posted 3 different answers to this question....I believe this last one is correct.

 

[roger]

Don, the equipment branch can be shed, any particular equipment that must remain in operation can be supplied from the critical branch.

Roger

 

[Smart $]

This is a confusing question. Taking another look at 517.30(B)(5) there is no provision that would permit the shedding of any of the loads listed in the question. The loads listed there are all required loads for an Article 517 installation.
Yes, I know that I have posted 3 different answers to this question....I believe this last one is correct.

Yes, if you only look at Article 517 out of context with other applicable Articles...

517.26 Application of Other Articles. The essential electrical system shall meet the requirements of Article 700, except as amended by Article 517.

So unless we find somthing in Article 517 that amends 700.5(B), there is no correct or best choice answer.

517.30(B)(5) mentions "optional loads... not specifically named in Article 517" shall be shed upon generator overload. So it does not explicitly state essential loads (which are specifically named in Article 517) cannot be shed.

I have yet to find anything that states any load cannot be shed

 

[guschash]

0vercurrent Protection VI 700.27 Coordination in 2008 workbook. 20-amp branch circuit can not cause the protective device supplying the branch-circuit panelboard to open. Because the purpose of emergency system is to provide power to essential life safety systems in a building or facility ......

 

[don_resqcapt19]

Don, the equipment branch can be shed, any particular equipment that must remain in operation can be supplied from the critical branch.

Roger

Roger,
Where does the NEC say that?

 

[roger]

Roger,
Where does the NEC say that?

Don, the NEC doesn't but, NFPA 99 4.4.1.1.3 only prohibits the Life Safety and Critical branches (Emergency Systems) from being shed and allows other essential loads to be shed which would be the Equipment branch.

Roger

 

[wirebender]

What is the equipment branch?
I cannot find it in the code.

 

[roger]

What is the equipment branch?
I cannot find it in the code.

To be correct it should be Equipment System as described in 517.30 and 34.

Roger