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Thread: Respective Branches for Legally Required and Optional Standby Loads

  1. #11
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    Quote Originally Posted by steve66 View Post
    Yes, your are right - he did say legally required. And if that is the case, then I agree with your answer.

    But it really makes me scratch my head because to the best of my knowledge, I have never ran across a "legally required system".

    So now I'm wondering if I have been mis-classifying systems. I know I have asked the difference between what systems are emergency and what are legally required, but I'm not sure I ever got an answer that was definitive.

    Almost all buildings require egress lighting and exit lighting with a second source of power. I have always assumed those lights and exit signs are "Emergency Systems". The IBC even uses the phrase "emergency power".

    So are exit lights and dual head egress lights emergency, or legally required?
    The IBC requires that many elevators be supplied by a legally required standby system.

  2. #12
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    Quote Originally Posted by steve66 View Post
    Yes, your are right - he did say legally required. And if that is the case, then I agree with your answer.

    But it really makes me scratch my head because to the best of my knowledge, I have never ran across a "legally required system".

    So now I'm wondering if I have been mis-classifying systems. I know I have asked the difference between what systems are emergency and what are legally required, but I'm not sure I ever got an answer that was definitive.

    Almost all buildings require egress lighting and exit lighting with a second source of power. I have always assumed those lights and exit signs are "Emergency Systems". The IBC even uses the phrase "emergency power".

    So are exit lights and dual head egress lights emergency, or legally required?
    Unless I misunderstand your question, the code at least touches it. Some people here have the ability to cut and paste I don't, but article 700 is only for legally required power ESSENTIAL for safety to human life. For article 701 there is an informational note that gives examples. This, like many things is an AHJ decision. The University I do a fair amount of work at, for example has been incorrectly mixing there loads for a long time. They have a lot of refrigeration in one part where loss of it could result in release of bio hazards. That is supposed to be 701 power.


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  3. #13
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    Thank you for the reply's greatly appreciated!

    As far as my research has gone the IBC and IFC both identify Emergency and standby systems- Emergency being 700 defined as backup power within 10 seconds, and Standby power being Legally Required defined as back up power within 60 seconds. Optional standby of course is not defined.

    There is a catch all, both IBC and IFC state emergency systems are an acceptable substitute for standby systems.. So theoretically you could place all required loads on Emergency and have an optional standby for customer requested loads.

    Also the NFPA 99 does segregate the transfer switches and systems, but that only applies to hospitals unfortunately.

    My issue is I have an existing high rise Building, Existing 3 separate systems, and the engineer wants to mix the legally required and optional standby loads at the point where the final circuits branch from the panels, even though originally a separation was made in the systems.. It just seems wrong, why would the NEC even define the two systems if you could always just mix the legally required and optional standby in the same panels? He is stating its a cheaper option and a practice they do all over.

    Head scratcher for sure

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    Just to clarify as well.. When I say "So theoretically you could place all required loads on Emergency and have an optional standby for customer requested loads" I mean the required emergency and standby loads required by the IBC and IFC

  5. #15
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    Quote Originally Posted by Sam@CEgeeks View Post
    Just to clarify as well.. When I say "So theoretically you could place all required loads on Emergency and have an optional standby for customer requested loads" I mean the required emergency and standby loads required by the IBC and IFC
    I don't see that in regards to the NEC. In my opinion the AHJ could classify all the loads you are referring to as Emergency loads and feed them from the emergency panel, but you couldn't have legally required standby loads fed from the same panel as article 700 loads. The end result is the same as that you describe but the semantics are technically different.


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