The National Electrical Manufacturers Association (NEMA) published NEMA LE 4-2012 Recessed Luminaires, Ceiling Compatibility.
NEMA LE 4-2012 contains definitions, dimensions, and tolerances for recessed luminaires designed to use fluorescent, high-intensity discharge, and incandescent light sources. Drawing that show examples of fluorescent lamps also apply to high-intensity discharge, compact fluorescent, incandescent, and other lamp sources. This standard does not apply to hard metric dimensioned products; soft metric dimensions or direct metric conversions, however; may be applied throughout this standard as one inch equals 25.4 millimeters.
NEMA is the association of electrical equipment and medical imaging manufacturers, founded in 1926 and headquartered in Arlington, Virginia. Its member companies manufacture a diverse set of products including power transmission and distribution equipment, lighting systems, factory automation and control systems, and medical diagnostic imaging systems. Worldwide annual sales of NEMA-scope products exceed $120 billion.
