Life Safety vs EM

Alwayslearningelec said:
What differentiates or determines the difference life Safety circuit from emergency circuits ? Thanks.
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Well u can't run life safety circuits in the same raceway as normal power but u can run emergency (stand-by and optional) circuits with normal circuits. Also, u cant have life safety circuits in the same enclosures as normal power but u can have normal power circuits in the same enclosures with standby and optional emergency circuits. If u look at A700 which deals with life safety circuits, A701 which deals with standby systems, and A702 which deals with optional emergency circuits, these articles will let u know the differences between the circuits.
 
lordofthisworld said:
Well u can't run life safety circuits in the same raceway as normal power but u can run emergency (stand-by and optional) circuits with normal circuits. Also, u cant have life safety circuits in the same enclosures as normal power but u can have normal power circuits in the same enclosures with standby and optional emergency circuits. If u look at A700 which deals with life safety circuits, A701 which deals with standby systems, and A702 which deals with optional emergency circuits, these articles will let u know the differences between the circuits.
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The word emergency should never be used to refer to Article 702 Optional Standby System as that creates confusion with Article 700 Emergency Systems. Article 701 is Legally Required Standby Systems.
The application of Articles 700 and 701 is triggered by rules in the building and life safety codes.
 
Alwayslearningelec said:
What differentiates or determines the difference life Safety circuit from emergency circuits ? Thanks.
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If you are trying to differentiate between loads that are Article 700 Emergency or Article 701 Legally Required Standby, look to your adopted building code. For example, if your adopted building code happened to be the IBC 2024, you look in Chapter 27 and anywhere it says Emergency Power System, you look at Article 700 of the NEC. If the IBC Chapter 27 says Standby Power System, you look at Article 701 of the NEC.

CHAPTER 27 ELECTRICAL - 2024 INTERNATIONAL BUILDING CODE (IBC)

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.
codes.iccsafe.org codes.iccsafe.org
 
Spent my last ten working years as an electrician in a large hospital. I asked several times about the emergency power / life safety breakdowns but never received any. The hospital purchased special cell phones that would only work within two blocks of the hospital for hundreds of nurses that worked there. Was confusing on every no ER,ICU, OR'S or NICU units where to pull 120 volt power from for charging stations.Was close to 50/50 EM or normal power. Older section of hospital had four natural gas generators that were used maybe 6 times every summer to peak shave 2 or 3 MWatts. Had to turn on steam chillers & shutdown electric chillers that ran on motors. Forget how many levels the emergency generators had buy while one was down for repairs & peak shaving a gen set went down and emergency power that was operating AHCU units transferred thier power to normal Power. Great thing all of the AHCU fans were on VFD'S that performed flawless flying starts.
 
garbo said:
Spent my last ten working years as an electrician in a large hospital. I asked several times about the emergency power / life safety breakdowns but never received any. The hospital purchased special cell phones that would only work within two blocks of the hospital for hundreds of nurses that worked there. Was confusing on every no ER,ICU, OR'S or NICU units where to pull 120 volt power from for charging stations.
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Actually 517.33, 517.34, and 517.35 spell the differences out quite thoroughly. ER's, ICU's, OR's, NICU's etc... would not have anything connected to the Life Safety Branch with the exception of FA, Exit signs, and egress lighting. For the critical Tasks 517.34(A) covers it as well as staff communications.
 
Always good to start with Article 100 definitions, and the index.

Emergency Systems:
Those systems legally required and classed as emergency by municipal, state, federal, or other codes, or by any governmental agency having jurisdiction. These systems are intended to automatically supply illumination, power, or both, to designated areas and equipment in the event of failure of the normal supply or in the event of accident to elements of a system intended to supply, distribute, and control power and illumination essential for safety to human life.
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Life Safety Branch

A system of feeders and branch circuits suppling power for lighting, receptacles, and equipment essential for life safety that is automatically connected to alternate power sources by one or more transfer switches during interruption of the normal power source.
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Notably, "Life Safety Branch" is only used in article 517 as far as I know, where it is described as part of the 'Essential Electrical System', which is also defined in article 100.
A system comprised of alternate power sources and all connected distribution systems and ancillary equipment, designed to ensure continuity of electrical power to designated areas and functions of a health care facility during disruption of normal power sources, and also ...
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...it goes on, but I highlighted the important part.

Essentially, emergency systems apply to many different types of facilities, where able people need things like lighting to safely move around a building or evacuate it in the event a normal supply fails. Allowing safe evacuation of the building may be sufficient for such systems. The Life Safety Branch is specific to health care facilities, and part of keeping the facility operating as it needs to keep people alive in the event of an outage. I believe 'equipment that is essential for life safety' must also include things like medical equipment that is directly keeping people alive, but I'll let the 517 experts elaborate.

Emergency Systems are article 700. Life Safety Branch is in article 517.
 
roger said:
Actually 517.33, 517.34, and 517.35 spell the differences out quite thoroughly. ER's, ICU's, OR's, NICU's etc... would not have anything connected to the Life Safety Branch with the exception of FA, Exit signs, and egress lighting. For the critical Tasks 517.34(A) covers it as well as staff communications.
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Thanks. Even in retirement enjoy keeping up with NEC. Will be reading over these there 517 Articles. Besides Mike Holts great daily graphic read his & Charlie Trout daily code questions & enjoy EC & M magazine. The hospital that I retired from always went above & beyond minimums. One being that believe JACHO required that halve of hospital elevators be backed up by emergency power. They had over 20 elevators all backed up by emergency power. Elevator lobbies that had four elevators were on two different ATS'S so if one ATS failed two would remain operating. Same with ER AHCU'S.
roger said:
Actually 517.33, 517.34, and 517.35 spell the differences out quite thoroughly. ER's, ICU's, OR's, NICU's etc... would not have anything connected to the Life Safety Branch with the exception of FA, Exit signs, and egress lighting. For the critical Tasks 517.34(A) covers it as well as staff communications.
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don_resqcapt19 said:
The word emergency should never be used to refer to Article 702 Optional Standby System as that creates confusion with Article 700 Emergency Systems. Article 701 is Legally Required Standby Systems.
The application of Articles 700 and 701 is triggered by rules in the building and life safety codes.
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So when it comes to "critical" systems or "back up" power it can fall into??

1. 700 EM Systems
2. 701 Legally Required Standby
3 702 Optional Standby Systems?

If someone call something "emergency" doesn't mean it's 701 or 702 and 701 and 702 wouldn't be considered emergency???
 
I would say the designer is referring to article 700 but I would send an RFI asking for clarification.
 
jaggedben said:
Notably, "Life Safety Branch" is only used in article 517 as far as I know, where it is described as part of the 'Essential Electrical System', which is also defined in article 100.
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2023 NEC moved all definitions to art 100. Before then if a definition was only used in one section (like 517) it appeared in the XXX.2 portion of that section and the definition only applied to use in that section. Art 100 was for definitions that applied throughout all of NEC
 
Alwayslearningelec said:
So when a drawing note says "life safety" what article is that? All three?
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As I think Roger was implying, if the plans say life safety in reference to circuiting, wiring or panels, on a project other than healthcare they are using it improperly. Life Safety is one of the essential systems in healthcare, only.
 
Strathead said:
As I think Roger was implying, if the plans say life safety in reference to circuiting, wiring or panels, on a project other than healthcare they are using it improperly. Life Safety is one of the essential systems in healthcare, only.
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And I think NEC should have left definitions that only apply to one section of the document within the section it applied to. This would have been one of them.
 
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