On a large commercial job. There is a spec for the penetrations that requires a rigid conduit sleeve with a 1/4 gap around elec conduit being sleeved, rockwool, and fire caulk.
I am wondering why the sleeve. This is for penetrations in sheetrock or masonry rated walls. It seems to me there is just a bigger hole made by sleeving, even if it does allow for rock wool.
Hoping someone can shed a little light on this.