Non-ICs used in lower floor ceilings such as kitchens and dropped ceilings. I still don't like them because most make Budweiser cans look strong. They leak air like a sieve by design. If used legally into attic, they can contribute significantly to depressurization. Even IC rated leak unless caulked to drywall. Another problem with even IC is using higher wattage bulbs than designed.

I assisted on the investigation of a fire once where it was caused by improper wiring in an IC can. The electrician stripped away way too much outer sheathing exposing free conductor to the box without a Romex clamp. Those knock outs leave a sharp burr. It sawed through the insulation and energized the fixture. The original was burnt to a crisp so I suggested an exemplar. We cut one out of the rest of the ceiling (much of room still intact) and sure enough all of them wired alike. Turns out the kid doing the wiring would cut away two feet of sheathing then fail to trim the free conductor to a reasonable ~8" and no clamps. Clamps take too much time, right?

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disgusted with some people on this forum. Out of here!