Fire-rated emergency feeders

J

Junior_EE

Member
Location
New York City
Our state follows the 2023 version of the NEC. We need to 2-hour rate our emergency feeders. Here is the relevant code section on doing so, from our version of 700.10(D):

(1) Feeder-Circuit Wiring​


Feeder-circuit wiring shall meet one of the following conditions:
  1. The cable or raceway is installed in spaces or areas that are fully protected by an approved automatic fire protection system.
  2. The cable or raceway is protected by a listed electrical circuit protective system with a minimum 2-hour fire rating.
    Informational Note No. 1: See UL 1724, Fire Tests for Electrical Circuit Protection Systems, for one method of defining an electrical circuit protective system. The UL Guide Information for Electrical Circuit Integrity Systems (FHIT) contains information to identify the system and its installation limitations to maintain a minimum 2-hour fire-resistive rating and is available from the certification body.
  3. The cable or raceway is a listed fire-resistive cable system with a minimum 2-hour fire rating.
    Informational Note No. 2: See UL 2196-2017, Standard for Fire Test for Circuit Integrity of Fire-Resistive Power, Instrumentation, Control and Data Cables, for one method of defining a fire-resistive cable system.
  4. The cable or raceway is protected by a listed fire-rated assembly that has a minimum fire rating of 2 hours and contains only emergency circuits.
  5. The cable or raceway is encased in a minimum of 50 mm (2 in.) of concrete.

If we run the feeder outside of the building, can the building itself be considered a listed fire-rated assembly? As in, can we simply run regular EMT and conductors outside of the building? For various reasons, we cannot run inside the building. The building is mostly masonry block for the exterior.
 
I don't see outside of the building on that list of acceptable wiring methods. The building doesn't have sprinklers per condition 1?
 
infinity said:
I don't see outside of the building on that list of acceptable wiring methods. The building doesn't have sprinklers per condition 1?
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We cannot run inside the building. Our belief is that the exterior of the building itself is considered a fire-rated assembly (#4), similar to running regular conduit/wire inside of a 2hr-rated room within the building.
 
Junior_EE said:
We cannot run inside the building. Our belief is that the exterior of the building itself is considered a fire-rated assembly (#4), similar to running regular conduit/wire inside of a 2hr-rated room within the building.
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That sounds like a stretch but if you can find something in the building code that says "that the exterior of the building itself is considered a fire-rated assembly" go for it. And what is the reason you cannot run inside the building?
 
infinity said:
I don't see outside of the building on that list of acceptable wiring methods. The building doesn't have sprinklers per condition 1?
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Most the time, the wiring method, even in a structure with sprinkler protection, is not installed in an area that actually has sprinkler protection. The wiring is typically installed in a concealed space, and few concealed spaces are fully protected by a fire sprinkler system.
 
To bring this back up.. how are your particular jurisdictions applying this code along with the the Building Code requirement of "continuity of fire protection"? That basically says you cant hold up a fire protected thing with something not fire protected. There are plenty of unprotected structures that have emergency feeders. Protecting an emergency feeder for 2 hours doesn't really benefit anyone if the building has burnt down in 30.

The NFPA has changed other codes (1221 to 1225 for example) to eliminate the need for protected wiring in unprotected structures.
 
Junior_EE said:
We cannot run inside the building. Our belief is that the exterior of the building itself is considered a fire-rated assembly (#4), similar to running regular conduit/wire inside of a 2hr-rated room within the building.
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Should be able to, service conductors ran outside a building do not require a two hour rating. They do make a wrap that goes around the conduit to give a two hour rating.
 
Wadzii said:
To bring this back up.. how are your particular jurisdictions applying this code along with the the Building Code requirement of "continuity of fire protection"? That basically says you cant hold up a fire protected thing with something not fire protected. There are plenty of unprotected structures that have emergency feeders. Protecting an emergency feeder for 2 hours doesn't really benefit anyone if the building has burnt down in 30.

The NFPA has changed other codes (1221 to 1225 for example) to eliminate the need for protected wiring in unprotected structures.
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It is usually for fire pump feeds.
 
Junior_EE said:
We cannot run inside the building. Our belief is that the exterior of the building itself is considered a fire-rated assembly (#4), similar to running regular conduit/wire inside of a 2hr-rated room within the building.
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What can't you run inside the building? VitaLink would seem to be perfectly acceptable.
 
Lexi B. said:
Running into this now. What code are they usually using?
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Fire pumps are usually fed from service conductors, if it is a tap from a pull section before the main, it must be treated as service conductors, and ran outside the building wether it’s in the slab, if ran inside, must be enclosed in a two hour fire rated system.
 
hillbilly1 said:
Fire pumps are usually fed from service conductors, if it is a tap from a pull section before the main, it must be treated as service conductors, and ran outside the building wether it’s in the slab, if ran inside, must be enclosed in a two hour fire rated
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Sorry - I am aware of the NEC implications. Was wondering if you had experience with building code(s) pertaining to fire rated cable. Just ran into an issue where there wasn't fire-rated structure to mount the cable assembly.
 
Why not use 2-hour fire rated shaft liner? Or like gadfly56 said. Use VitaLink. We use it when we don’t have a choice.
 
A bit late, but I can answer this question. I'm our engineer who makes fire resistive cable systems and can make this easy to understand. If you select fire resistive cable systems under 700.10(D), or other articles like 695, 517, 708, etc......then Article 728 must be used. That's where most get lost. 728 is a 1 page article designated for fire resistive cable systems. It has a couple really important things in there. First you don't need fire resistive cables INSIDE the fire rated rooms the cables serve, next if there is a conflict between 728 and the rest of the NEC....728 wins. Then 728 will mandate you follow the systems listing, which is a UL document called and FHIT XXX. In that document it designates these cables are required in the "fire zone" and 12 inches beyond that "fire zone". So what is a "fire zone"? The best definition is in the IBC under "fire area". Those are all interior buidling spaces. So if you're outside the buidling, you're no longer in the "fire zone/area" and you don't need fire resistive cables. I also see the term "Vitalink" used often....that is a brand name. Like Megger testing is actually Insulation Resistance testing, but it's been marketed well. There are other more cost effective brands available so don't be misled by marketing and sales tactics. Vitalink and others offer an MC type cable, but it's not like normal MC. It's very soft and easily damaged (soft copper armor). If damaged, it's crazy expensive to fix (thousands at a minimum). In almost all cases, a RHW-2 in EMT system is much less expensive and safer/easier to install. MC systems don't need conduit but they do cost more per foot, require lots of equipment rentals and take 3 to 5 times more labor over that of EMT systems. Don't look at the cost per foot, look at the installed costs including labor! FHIT 25E is a great EMT system whereas FHIT 50 and FHIT 120 are both MC systems. Don't get me wrong, MC systems do have their place, particularly if you need sets, but outside of that an EMT system is always the way to go. Single conductor MC have a free air rating and thus a higher ampacity often reducing the sets needed. Another thing to remember is that the 2026 NEC is changing the concrete encasement rule. It's going to 5 inches encased from the older 2 inch rule. Ping me if you have a project that needs this. About 20% of the reviews I make don't even need this stuff and that can save a lot of money.
 
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