The original recessed lighting fixture was a single skin can intended to be used with incandescent bulbs or halogen bulbs.
The six inch can takes an incandescent bulb while the three inch can takes a halogen bulb.
The problem with the original style of recessed lighting can is both types of bulbs get very hot.
That heats up the housing, and it gets very hot (and I mean VERY hot).
The hot housing protrudes into your attic and can come into contact with your insulation.
If it does, it can catch your insulation on fire.
When recessed lighting fixtures were new, it was common to build a wood box around the fixture to prevent insulation from coming into contact with the can.
However, these days, you can buy double walled cans (rated IC for “Insulation Contact“) AND you can run compact fluorescent or LED bulbs, both of which run much cooler than either incandescent or halogen.
So… when you ready to install recessed lighting in your home, ensure your cans are rated IC so you never have this issue.
And speaking of recessed lighting for your home ….. we would love to install some for you when you live in or near San Jose.