Life Support Branch

don_resqcapt19

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Staff member
Location
Illinois
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retired electrician
Right- on the basis that the building will be evacuated. Or people will move to another location within a large building. As such there must be continuity of electrical service to fire alarm panel, egress lights, and command intercom. Ditto for the fire pump, despite being a separate branch.

What life safety would there be if all the exits signs and stairwells went dark? I can't find my way out...
The four list items in 517.26 were added for the 2020 code. Here is the substantiation for that addition.
As the Chair of NFPA 99 Electrical Systems Committee (HEA-ELS), I am submitting this proposal to improve the correlation between NFPA 99 and NFPA 70. The substantiation of this proposal is as follows: It has been established by the NFPA Standards Council that NFPA 99 has jurisdiction over performance requirements for electrical systems in health care facilities while NFPA 70 has jurisdiction over the installation requirements. The proposed addition is the result of the 99 HEA-ELS TC agreeing that the life safety branch is required to conform to Article 700 with the exception of several performance requirements. Section 700.4 speaks to capacity of the system which NFPA 99 already addresses in detail. Section 700.10(D)(1) can possibly impose fire protection requirements in excess of what a building code might require for the rest of the structure. Section 700.17 is slightly modified and 700.32 is also identified as not applying due to the documented decision that selective coordination is a performance issue under the jurisdiction of NFPA 99.
Again, any change in this would rest with the technical committee for NFPA 99. The CMP for the NEC does not have the authority to make the change.
 

mbrooke

Batteries Not Included
Location
United States
Occupation
Electricity
The four list items in 517.26 were added for the 2020 code. Here is the substantiation for that addition.
I was looking for that, thank you! :)

Again, any change in this would rest with the technical committee for NFPA 99. The CMP for the NEC does not have the authority to make the change.

Perhaps. Here is the 2014:

1614484760360.png


1981 NEC:

1614485089660.png

1971 NEC:

1614485875013.png

The NFPA 70, or whom ever set article 517 in creation has always wanted the life safety branch to comply with article 700. I'm well aware of the desire to harmonize, however, even with 4 exceptions much of 700 still holds true in the 2020 NEC. Including this:

1614486281385.png

While both life safety and critical require mechanical protection, life safety requires fire protection in addition to extensive physical segregation from normal power going beyond keeping circuits in separate conduit.

Its obvious (IMO) the intent is to keep the life safety branch energized during a fire.

Of course nothing such is hinted or required for the critical branch.

However, in the early development of the 1971 addition such was considered (and supported) for the life support branch- even giving the option of combining both branches at the hospital's discretion. But at the last minute this was changed without written record (to my knowledge), so rapidly even the graphic on page 70-333 of the 1971 NEC does not match the emergency system description on page 70-339 of the 1971 NEC.


1614486723075.png
 

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mbrooke

Batteries Not Included
Location
United States
Occupation
Electricity
See 6.7.5.1.2.2 in the 2021 edition of NFPA 99.
1614487221355.png

From the 2021.

Understood, but even with these modifiers much of article 700 still applies. The life safety branch is required to have a back-up during generator maintenance, be separate, segregated, restricted, protected, and very limited in what loads can be served (in turn limiting exposure). That would make sense given the word "life" in front of "safety"

Perhaps this can best be illustrated by what is routinely seen in the real world via actual examples. Aka actual practice, as meeting the requirements of both NFPA 99 and NFPA 70.
 

mbrooke

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Location
United States
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Electricity
See 6.7.5.1.2.2 in the 2021 edition of NFPA 99.

Ok, here is typical example. Starting with the basement- Black = Normal, Green = Critical, Blue = Equipment, Red = Life Safety:


1614488247434.png


Going up the building:

1614488536896.png


To describe the graphics above- normal, critical and equipment power while physically separate are run all the way up the building as single circuits sharing the same electrical rooms, shafts and interstitials without any fire protection on the busduct.

The life safety branch on the other hand is run up the building's core as independent circuits, conduit encased in concrete or 2 layers of gypsum board. Panels not located in the hallway are kept in independent electrical rooms. Any branches or sub feeders are above the sprinkler and run flush with beams or the corrugated floor diaphragm. Intentional or accidental there happens to be spray on fire proofing on the conduit when run horizontally.

Clear effort is made minimize the impact of fire and common mode failure on the continuity of the life safety branch.
 

mbrooke

Batteries Not Included
Location
United States
Occupation
Electricity
See 6.7.5.1.2.2 in the 2021 edition of NFPA 99.
And, a birds eye view of another example:

1614489561416.png


1614489575446.png


Notice how critical and normal power (in this case busduct) are within inches of each other, in the same room, without any consideration. On the other hand the life safety branch is run in concrete encased conduit, as well as the vertical branches coming out of the planelboard above. There are also cases of MI cable being used on the life safety branch in some jurisdictions.

It is clear that regardless of who holds the final word in NFPA 99, 70, 101 or the like the wording is such that the life safety circuit receives precedence and is likely to remain functioning during a fire or catastrophic failure of the normal power system.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Notice how critical and normal power (in this case busduct) are within inches of each other, in the same room, without any consideration. On the other hand the life safety branch is run in concrete encased conduit, as well as the vertical branches coming out of the planelboard above. There are also cases of MI cable being used on the life safety branch in some jurisdictions.

It is clear that regardless of who holds the final word in NFPA 99, 70, 101 or the like the wording is such that the life safety circuit receives precedence and is likely to remain functioning during a fire or catastrophic failure of the normal power system.
You are free to design and install it in a manner that exceeds the code requirements.

The extra fire protection of the EM or life safety branch is just one of the things that the health care facilities technical committee says you are not required to do. Note that even in other facilities, the emergency wiring does not require that extra fire protection unless the building meets the conditions set forth in 700.10(D)(1).

The requirement to keep the life safety (emergency branch) separate from other wiring still applies as the rule in 517.26 only says that the fire protection part of 700.10 does not apply to health care facilities. The other wiring protection requirements in 700.10 apply.
 

mbrooke

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Location
United States
Occupation
Electricity
You are free to design and install it in a manner that exceeds the code requirements.

The extra fire protection of the EM or life safety branch is just one of the things that the health care facilities technical committee says you are not required to do. Note that even in other facilities, the emergency wiring does not require that extra fire protection unless the building meets the conditions set forth in 700.10(D)(1).

The requirement to keep the life safety (emergency branch) separate from other wiring still applies as the rule in 517.26 only says that the fire protection part of 700.10 does not apply to health care facilities. The other wiring protection requirements in 700.10 apply.

Where have they specifically said it is not required, minus the exclusion of 710.10 (D)?

700.10 (C) still applies. Most of article 700 still applies giving the life safety branch separate rooms, back-up generation during maintenance, some selective coordination, restricted coverage, ect.

The life safety branch is far more likely to be available and remain in service than the critical branch.

In fact the rules between the generator and ATS are stronger that after the ATS for the critical branch.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
The extra fire protection of the EM or life safety branch is just one of the things that the health care facilities technical committee says you are not required to do. Note that even in other facilities, the emergency wiring does not require that extra fire protection unless the building meets the conditions set forth in 700.10(D)(1).

The requirement to keep the life safety (emergency branch) separate from other wiring still applies as the rule in 517.26 only says that the fire protection part of 700.10 does not apply to health care facilities. The other wiring protection requirements in 700.10 apply.
This exception for the extra fire protection for health care facilities has always left me puzzled. Even more so now that I notice that the 2017 NEC 700.10(D)(1) specifically says (D)(3) "Health care occupancies......".

So NFPA 99 says you don't need extra fire protection for health care occupancies, and the NEC says the exact opposite - "you do need extra fire protection for health care occupancies."
 

don_resqcapt19

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Staff member
Location
Illinois
Occupation
retired electrician
This exception for the extra fire protection for health care facilities has always left me puzzled. Even more so now that I notice that the 2017 NEC 700.10(D)(1) specifically says (D)(3) "Health care occupancies......".

So NFPA 99 says you don't need extra fire protection for health care occupancies, and the NEC says the exact opposite - "you do need extra fire protection for health care occupancies."
I don't see that in my code book. Maybe you are talking about 700.12(3)? If so, 700.12(3) applies. As I said in precious posts, the requirements of 700 apply to the life safety branch unless 517.26 says otherwise. 700.12 is not one of the 4 list items in 517.26.
 

mbrooke

Batteries Not Included
Location
United States
Occupation
Electricity
I don't see that in my code book. Maybe you are talking about 700.12(3)? If so, 700.12(3) applies. As I said in precious posts, the requirements of 700 apply to the life safety branch unless 517.26 says otherwise. 700.12 is not one of the 4 list items in 517.26.

So the question is, why does the life safety branch receive fire protection and not the critical branch?
 

don_resqcapt19

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Staff member
Location
Illinois
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retired electrician
So the question is, why does the life safety branch receive fire protection and not the critical branch?
What requires the critical branch to have fire protection? I see the critical branch as an Article 701 installation, not an Article 700 one.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
I don't see that in my code book. Maybe you are talking about 700.12(3)? If so, 700.12(3) applies. As I said in precious posts, the requirements of 700 apply to the life safety branch unless 517.26 says otherwise. 700.12 is not one of the 4 list items in 517.26.
Interesting.

My 2017 NEC Handbook has 700.10(D) 1 through (D) 4 and lists health care occupancies.

The free online version of the 2017 NEC only has (D) 1 through 3, and omits health care occupancies.
 

d0nut

Senior Member
Location
Omaha, NE
Interesting.

My 2017 NEC Handbook has 700.10(D) 1 through (D) 4 and lists health care occupancies.

The free online version of the 2017 NEC only has (D) 1 through 3, and omits health care occupancies.
That is because there was a TIA that removed health care occupancies from that list. Healthcare is not under the purview of NFPA 70, it is an NFPA 99 issue. The tie between NFPA 99 and NFPA 70 is article 517. The fact that health care requirements were in Article 700 was that CMP overstepping their role.
 

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steve66

Senior Member
Location
Illinois
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Engineer
That is because there was a TIA that removed health care occupancies from that list. Healthcare is not under the purview of NFPA 70, it is an NFPA 99 issue. The tie between NFPA 99 and NFPA 70 is article 517. The fact that health care requirements were in Article 700 was that CMP overstepping their role.
I looked for something like that here:

NFPA 70®: National Electrical Code®

And couldn't find it. Not that I look again, I see the little text that says "Show More". 🙂
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Interesting.

My 2017 NEC Handbook has 700.10(D) 1 through (D) 4 and lists health care occupancies.

The free online version of the 2017 NEC only has (D) 1 through 3, and omits health care occupancies.
I am using NFPA Link...that is one issue with that platform. It makes changes when TIAs are issued or when mistakes are corrected. It can become a problem for AHJs, as the only enforceable code is that actual version that was adopted by the unit of government that enforces the code. The TIAs and other changes that are made online are not legally enforceable unless specifically adopted by that same unit of government.
 
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