I'm presently working a high rise where the use of ENT is installed through firewalls horizontally without the use of sleeves but using intumescent caulking on both sides of the penetration and plated above and/or below using stud material packed with mineral fiber insulation (I've never seen this type of method before, except for EMT, Ridgid or Flexible Metal Conduit. I've always sleeved penetrations when using a material that will reduce in size due to fire). I looked up ENT "Uses Permitted and Uses Not Permitted," and all it mentions is a 15 minute rating of the barrier when "concealed in walls, floors and ceilings." Nowhere does it mention the integrity of the firewall itself, nor does it mention through firewall penetrations. I'll have some pics later.