2 hour rated feeders

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mshields

Senior Member
Location
Boston, MA
I've encountered a building inspector who thinks the branch circuit feeding battery packs used in a medical office building needs to be 2 hour rated. This is obviously wrong but I want to make sure I use the most compelling argument to parry this thrust.

A. Assuming I correct to call the conduit and wire going to the battery pack, a branch circuit, branch circuits are not required to be 2 hour rated.
B. The batteries are the EESS
C. This MOB has a generator which it uses at their discretion but which is set up for OS loads only. It's presence in my mind is immaterial so long as the egress paths are protected with 90 minute battery packs. But we do MOB's all the time that don't have generators and therefore don't have any 2 hour rated feeders.

Regardless, I feel like perhaps I am missing a cu de gras code reference. Can anyone help
 

Shoe

Senior Member
Location
USA
Here's your silver bullet:

NEC 700.12 (F) Unit Equipment

blah blah blah...

Unit equipment shall be permanently fixed in place and shall have all wiring to each unit installed in accordance with the requirements of any of the wiring methods in Chapter 3. Flexible cord and plug connection shall be permitted, provided that the cord does not exceed 3ft in length.

blah blah blah...

After reading this to him, do as iwire suggested
 

Pharon

Senior Member
Location
MA
I've encountered a building inspector who thinks the branch circuit feeding battery packs used in a medical office building needs to be 2 hour rated. This is obviously wrong but I want to make sure I use the most compelling argument to parry this thrust.

A. Assuming I correct to call the conduit and wire going to the battery pack, a branch circuit, branch circuits are not required to be 2 hour rated.
B. The batteries are the EESS
C. This MOB has a generator which it uses at their discretion but which is set up for OS loads only. It's presence in my mind is immaterial so long as the egress paths are protected with 90 minute battery packs. But we do MOB's all the time that don't have generators and therefore don't have any 2 hour rated feeders.

Regardless, I feel like perhaps I am missing a cu de gras code reference. Can anyone help
The best argument is A.

700.10(D)(1) deals with feeder-circuit wiring. As long as there is no OCPD at the battery pack, it's a branch circuit -- not a feeder. (Note: MA amendments eliminate 70010(D)(1)(1) as an option, as you know.)

700.10(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.

(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

Article 100 Definitions:

Branch Circuit. The circuit conductors between the final overcurrent
device protecting the circuit and the outlet(s).

Feeder. All circuit conductors between the service equipment,
the source of a separately derived system, or other power supply
source and the final branch-circuit overcurrent device.
 
Last edited:

mgookin

Senior Member
Location
Fort Myers, FL
I've encountered a building inspector who thinks the branch circuit feeding battery packs used in a medical office building needs to be 2 hour rated. This is obviously wrong but I want to make sure I use the most compelling argument to parry this thrust.

A. Assuming I correct to call the conduit and wire going to the battery pack, a branch circuit, branch circuits are not required to be 2 hour rated.
B. The batteries are the EESS
C. This MOB has a generator which it uses at their discretion but which is set up for OS loads only. It's presence in my mind is immaterial so long as the egress paths are protected with 90 minute battery packs. But we do MOB's all the time that don't have generators and therefore don't have any 2 hour rated feeders.

Regardless, I feel like perhaps I am missing a cu de gras code reference. Can anyone help

The whole concept of battery packs and means of egress illumination is that there will be no current flowing in the wiring. That being said, you don't even need the wiring to keep the battery powered lights on during the adverse event.

Maybe this (green) inspector is confusing it with fire pump requirements?
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
I've encountered a building inspector who thinks the branch circuit feeding battery packs used in a medical office building needs to be 2 hour rated. This is obviously wrong but I want to make sure I use the most compelling argument to parry this thrust.

A. Assuming I correct to call the conduit and wire going to the battery pack, a branch circuit, branch circuits are not required to be 2 hour rated.
B. The batteries are the EESS
C. This MOB has a generator which it uses at their discretion but which is set up for OS loads only. It's presence in my mind is immaterial so long as the egress paths are protected with 90 minute battery packs. But we do MOB's all the time that don't have generators and therefore don't have any 2 hour rated feeders.

Regardless, I feel like perhaps I am missing a cu de gras code reference. Can anyone help

Well, the first few words of your statement tells the story. He is a "building inspector" and obviously not an "electrical inspector" so that was the first hurdle you faced with this individual. So at this point I am seeing three and maybe five solutions on the table to your problem.

#1)- Hit him in the head with a "ball peen hammer".
#2)- Explain 700.12(F) to the "building inspector" .
#3)- Explain 700.10(D)(1) to the "building inspector".
#4)- Explain 700.12(A) and (F) to the "building inspector"
#5) -Try an 8lb sledge hammer (with a full swing) if the ball peen hammer does not work.

So I guess the choices are clear.....item #1 and # 5 will certainly get easier results unless the back up inspector is just as confused then it just becomes more work and a clean up effort and quite messy.

My opinion is try both options #4 and if the negotiations turn south, you always have options #1 and #5 as a well planned backup plan.:angel:
 
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