Now Including Exits

Published On
Apr 15, 2020

Periodically, a change in the National Electrical Code occurs that is long overdue, such as 2020‘s new Section 300.25. This change may have long-term consequences for electrical contractors, especially if the designer, estimator and installing electricians are not familiar with it. The origin of this change is located in Section and annex explanation in the NFPA 101, Life Safety Code. It has been in the NFPA 101 code for a couple of cycles, and it’s only now showing up in the NEC .

Section 300.25, “Exit Enclosures (Stair Towers),” requires clarification, since the phrase “exit enclosures” is more likely architect and builder’s language than something most in the electrical industry would recognize. The definition of “exit” in NFPA 101 is “that portion of a means of egress that is separated from all other spaces of a building or structure by construction or equipment as required to provide a protected way of travel to the exit discharge.” “Exit discharge” is the portion of a means of egress between the exit termination and a public way. Putting the terms together into the title phrase means the exit enclosure construction or stair tower permits egress from higher building floors to safety. Electricians recognize the term “enclosures” for panelboards in Article 312 and metal boxes in Article 314 differently than the use of enclosures as used in NFPA 101. The term “enclosure” used in NFPA 101 means enclosing the exiting stairwells and towers.

The text within Section 300.25 is “Where an exit enclosure is required to be separated from the building, only electrical wiring methods serving equipment permitted by the authority having jurisdiction [AHJ] in the exit enclosure shall be installed within the exit enclosure.”

A new informational note states, “For more information, refer to NFPA 101-2018, Life Safety Code”

Based on this new text, any stairwell or stairway separated from the building by fire-rated separation can only have electrical wiring that is approved by the AHJ. The text shown in in NFPA 101 stated only electrical conduit can serve equipment in the stairwell or stairway, so only it can enter this area.

However, the annex, which is only explanatory information, provided in NFPA 101 states as follows: “Penetrations for electrical wiring are permitted where the wiring serves equipment permitted by the authority having jurisdiction to be located within the exit enclosure, such as security systems, public address systems, and fire department emergency communications devices.”

Panel 3 accepted the expanded wiring method provided in the annex information for the NEC mandatory text rather than the limited “conduit” only provided in the NFPA 101 text. Limiting the wiring method in the exit to just conduit would be too restrictive, since the annex information for provides the term raceway, rather than conduit. Many people inadvertently use conduit to apply to all raceways, and this makes a lot of difference in the type of wiring methods permitted in these restricted areas.

Remember, when installing raceways and other wiring methods into these stairways and stairwells, it is still necessary to comply with 300.21, dealing with spread of fire and products of combustion. This requirement is: “Electrical installations in hollow spaces, vertical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased. Openings around electrical penetrations into or through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire-resistance rating.”

Not only do the openings around the electrical penetrations into the stairways or stairwell be firestopped, the wiring method must be matched to the fire-rated assemblies based on the actual design of the fire-rated assembly. The informational note in 300.21 states that directories of electrical construction materials published by qualified testing laboratories contain many listing-installation restrictions necessary to maintain the fire-resistant rating of assemblies where penetrations or openings are made.

Following these requirements for fire-stopping and using the proper wiring method for exit enclosures for stairwells, stairways and stair towers will ensure compliance with the NEC , the Life Safety Code and the building codes.

About the Author

Mark C. Ode

Fire/Life Safety, Residential and Code Contributor

Mark C. Ode is a lead engineering associate for Energy & Power Technologies at Underwriters Laboratories Inc. and can be reached at 919.949.2576 and

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