2 hour rated Emergency Feeders

[mshields]

I'm working on the design of a building that's shaped like an L. And on the ground floor, there is the main Emergency Electrical room which is on, shall we say, one leg of the L and then stacked on the other side of the L are Emergency closets for all of the Emergency closets serving this 5 story hospital.

My design documents call for MI cable to be run through the building from the Main room to the stack of closets.

The EC is proposing as a VE measure that we underground from the Main room to the ground level closet and is suggesting that since it's outside we can do this with regular pipe and wire.

a) in accordance with the letter of the code, is this true.

b) what's your opinion on the application and it's reliability as compared to the MI inside the building?

Thanks,

Mike

 

[bwyllie]

I think it's acceptable and will be much cheaper and an easier install than MI cable. Another cheaper alternative to MI cable is the CI cable that is 2 hr rated when installed in steel conduit.

 

[anbm]

I'm working on the design of a building that's shaped like an L. And on the ground floor, there is the main Emergency Electrical room which is on, shall we say, one leg of the L and then stacked on the other side of the L are Emergency closets for all of the Emergency closets serving this 5 story hospital.

My design documents call for MI cable to be run through the building from the Main room to the stack of closets.

The EC is proposing as a VE measure that we underground from the Main room to the ground level closet and is suggesting that since it's outside we can do this with regular pipe and wire.

a) in accordance with the letter of the code, is this true.

b) what's your opinion on the application and it's reliability as compared to the MI inside the building?

Thanks,

Mike

Why do you need to run 2 hour rated (I assume your meant 2-hour fire rated) emergency feeders in this case? What are these feeders for?

 

[iwire]

The EC is proposing as a VE measure that we underground from the Main room to the ground level closet and is suggesting that since it's outside we can do this with regular pipe and wire.

a) in accordance with the letter of the code, is this true.

b) what's your opinion on the application and it's reliability as compared to the MI inside the building?

I think it is an excellent bit of VE and IMO is likely to outlast the MI in a fire. By the time the underground conduit and conductors could be compromised there is no doubt anyone left in the building would be long dead.

 

[copper chopper]

I think they are talking about 700.11d which states this:D) Fire Protection.
Emergency systems shall meet the
additional requirements in (D)(1) through (D)(3) in assembly
occupancies for not less than 1000 persons or in buildings
above 23 m (75 ft) in height with any of the following
occupancy classes: assembly, educational, residential, detention
and correctional, business, and mercantile.
Informational Note: For the definition of
Occupancy Classification,
see Section 6.1 of NFPA
101-2009, Life Safety
Code
.
(1) Feeder-Circuit Wiring.
Feeder-circuit wiring shall meet
one of the following conditions:
(1) Be installed in spaces or areas that are fully protected
by an approved automatic fire suppression system
(2) Be a listed electrical circuit protective system with a minimum
2-hour fire rating
Informational Note: UL guide information for electrical
circuit protective systems (FHIT) contains information on
proper installation requirements to maintain the fire rating.
(3) Be protected by a listed thermal barrier system for electrical
system components with a minimum 2-hour fire
rating
(4) Be protected by a listed fire-rated assembly that has a
minimum fire rating of 2 hours and contains only emergency
wiring circuits.
(5) Be encased in a minimum of 50 mm (2 in.) of concrete
(2) Feeder-Circuit Equipment.
Equipment for feeder circuits


number 5 allows you to run the feeders the way the ec wants, I can assume the floor has not been poured yet or they want to pop outside and run outside the building and pop back in.. if they do so then where ever they have exposed conduits it has to be a listed 2 hr rating... I dont know where you would find out this info maybe the manufactrurer of all componets they wish to use in there installation... now if the floor has not been poured yet this is how we do it--- rigid 90 elbows on each end of the run comming up out of the floor into equipment and running sch-80 pvc underground inbetween. The trench in through the building is incased in slurry concrete. Which brings a question to mind if aluminuim wire is used in this application to save money is that rated for 2 hrs. hmmmmmm i must consult the ul ratings of AL wire insultion to confirm this....
however it does say that your install must meet 1 of the following: also on a job that size I would check through the spec-book and see if this is allowed or consult with the engineer, whatever there answer is, get it in writing...

 

[mshields]

one more twist

one more twist

The feeders I'm talking about for those of you for whom it was unclear are Emergency Feeders (i.e. Critical and Life Safety branches).

There is one further twist that the contractor is proposing namely that he wants to use MC Cable rated to be encased in concrete. The outside area we're looking to run through is very congested with underground utilities and this would faciliate making this path (as opposed to the inside path with MI) work.

To me, the only draw back is that if you had a fault and you had to pull new conductors, you'd be out of luck. But I've only ever seen that on very old circuits and even then, typically at splices. Given that we've got a very real challenge to fit all of these circuits in, I'm inclined to accept it. Would be interested in your thoughts.

Thanks,

Mike

 

[steve66]

The outside area we're looking to run through is very congested with underground utilities and this would faciliate making this path (as opposed to the inside path with MI) work.

Mike

That would be my biggest concern. Any chance your emergency feeders will be hit during any future utility work or repairs?

 

[mshields]

prospect of feeders being hit by future excavation

prospect of feeders being hit by future excavation

Well - it's going to be encased in concrete. I would think that would be a pretty robust installation.

Mike