Legally Required (smoke control) panel feeder - route through 2-hour rated stairwell?

[snik96]

I'm working on a high-rise building with pressurization fans / elevator control room on the rooftop. These are fed from a panel that's also on the rooftop, that is part of the Legally Required distribution system.

There is not a dedicated shaft available to route the panel feeder through vertically from the first floor, and maintain code-required 2-hour rating for smoke control.

I've heard of pressurization fan branch circuits being routed through fire-rated stairwells to maintain 2-hour rating. My question is, can the same be done for a panel feeder? If I run the conduit for the panel on the roof vertically through a 2-hour rated stairwell, is that an acceptable solution for the smoke control feeder?

 

[don_resqcapt19]

That may be an issue with 300.25.

 

[snik96]

Yeah, after some further discussion in the office, I think the consensus is the problem being the panel also services the elevator, which is a foreign system to the stairwell. If the panel were just servicing stairwell fans, then routing the panel feeder in the stairwell would be acceptable.

Not 100% sure that's correct, but seems likely.

 

[gadfly56]

If you use something like MI or VitaLink, which are inherently 2-hour, you wouldn't need a rated chase.

 

[d0nut]

If the panel were just servicing stairwell fans, then routing the panel feeder in the stairwell would be acceptable.

I would argue that it still would not be allowable to route the feeder in the stairwell. Section 1023.5 of the IBC only permits electrical raceway serving the interior exit stairway and terminating at a steel box not exceeding 16 square inches. The intent is to limit the number of penetrations into the protected exit stairwell as each penetration is a possible failure point during a fire event.