Low Voltage down lights

You're going to have to ask a licenced contractor this question. Unfortunately I don't have a copy of the wiring rules anymore.

In most locales in the U.S. it is required to have an enclosure (a galvanized metal box normally) around the recessed lamp assembly only if it is installed directly under an exterior roof or attic. The assemblies like Halo will generally have a magnetic transformer which is not a problem with ambient heat. If the low voltage trim itself houses an MR16 lamp (most likely), the heat is most ly directed forward in the focus. USHIO and some other MR16 lamp manufacturers have aluminized coatings on the back of the reflector that retards the light and the heat from dispersing into the enclosure or into the surround area above the ceiling. The style brand name of the USHIO is "Reflekto." They're manufactured in the USHIO plant in Belgium and are of very high quality. Just stay a million miles away from lamps made in China or Indonesia. They are not to spec as to lamp life, color temperature or intensity (how Home Despot gets aways selling them is beyond me). They do usually state a 1,500 hr. lamp life but the USHIO lamp is in the 2,500 to 3,500 hour range an more! They have a 10,000 hour lamp that's more expensive but in the long run is cheaper operating. THe Home Despot 1,500 hour lamps rarely last beyond 1,000 hours.