700.10(D) Fire Protection.

Type MI cable (Mineral Insulated) installed as a listed electrical circuit protective system with a minimum 2-hour fire rating.
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Type MI cable (Mineral Insulated) installed as a listed electrical circuit protective system with a minimum 2-hour fire rating.

Code Change Summary: Protection requirements for emergency systems have changed.

Proper protection of the emergency system is critical. It would be foolish to install a feeder from an emergency power source using a flimsy wiring method that could easily be destroyed by the disaster that triggers the emergency system to intervene in the first place.

In the 2017 NEC, the list of occupancy types requiring additional feeder protection was expanded to include health care facilities where persons are not capable of self-preservation and educational occupancies with more than 300 occupants. The previous rules only applied to large assembly occupancies and buildings over 75 feet high. Adding certain educational occupancies and specific health care facilities to the group makes sense because these types of occupancies struggle with the same issues when it comes to safe and reliable evacuation procedures.

Another change occurred with clarifying the rules on feeder circuit protection. Revised code language makes the five rules easier to understand and apply.

The last change was to include special provisions for generator control wiring in 700.10(D)(3). A new sentence was added that states: The integrity of the generator control wiring shall be continuously monitored. Loss of integrity of the remote start circuit(s) shall initiate visual and audible annunciation of generator malfunction at the generator local and remote annunciator(s) and start the generator(s). This new requirement ensures that even if the control circuit that initiates generator startup is damaged, the generator will go into failsafe mode and switch itself on during an emergency.

Below is a preview of the NEC. See the actual NEC text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC edition of NFPA 70.

2014 Code Language:

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

(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

See actual NEC text for informational notes and remainder of the section.

2017 Code Language:

700.10(D) Fire Protection. Emergency systems shall meet the additional requirements in (D)(1) through (D)(3) in the following occupancies:

(1) Assembly occupancies for not less than 1000 persons

(2) Buildings above 23 m (75 ft) in height

(3) Health care occupancies where persons are not capable of self preservation

(4) Educational occupancies with more than 300 occupants

(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 suppression system.

(2) The cable or raceway is protected by a listed electrical circuit protective system with a minimum 2-hour fire rating.

(3) The cable or raceway is a listed 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.

See actual NEC text for informational notes and remainder of the section.

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700.10(D) Fire Protection.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is a code compliant method to provide proper fire protection for an emergency generator feeder in a building that is 100 feet tall?

A: Using rigid metal conduit as the wiring method.
B: Encasing the cable or raceway in 2 inches of concrete.
C: Using intermediate metal conduit as the wiring method.
D: Using PVC coated MC cable as the wiring method.
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