Most metal components, such as plaster frames, bar hangers, vertical‑adjustment brackets and butterfly brackets, of new construction housings are made from galvanized steel. Aluminum plaster frames are for use in very damp locations, or installations where non-magnetic properties are required (e.g. in MRI rooms). The heavy gauge bar hangers include a pair of metal bars which are extendible to fit between 16” spaced joists, and 24” spaced joists. They slide within two opposing sides of a plaster frame or butterfly brackets. Butterfly brackets are die-formed sheet‑metal brackets that accept commercial bar hangers and are mechanically attached to the vertical‑adjustment brackets through a slot.
Both new construction or remodel housings often come with a junction box which is typically disposed laterally of the housing, plaster frame or outboard of the plaster ring. The junction box is kept a certain distance from the luminaire in order to keep the driver from overheating. The junction box and its snap-on covers must be at least 0.05” thick if made of steel, and 0.09” if made of aluminum.
