Why do surface mount light fixtures not require the type of air gap that recessed lights permitting insulation contact do?

Question

A non-IC rated can light is supposed to have a 3 inch gap between it and any insulation. IC rated can lights have a double housing with an air gap to make insulation contact safe. On the other hand most surface mount lights have insulation inside the actual fixture very close to the bulb and electrical connections. Ex Should there be insulation inside a light fixture?

This seems very inconsistent to me. How is it that for can lights you need a large air gap or extra layers to keep the insulation from combusting, while for surface mount lights the insulation is right inside the light and its not combusting?

Answer 1

Insulation Contact means unrestricted insulation contact

Fixtures rated for Insulation Contact (IC for short) are rated this way because they are permitted to contact any type of insulation, even combustible insulation materials such as blown-in celluose, sprayed foams, and foam boards. However, in the context of the interior fixture, it's easy for a fixture manufacturer to specify that only non-combustible/heat-insensitive insulation materials such as fiberglass and mineral wool can be used, so they can simply specify a material that can take the high heat present.