In lighting practice the lamp is the light source itself, incandescent, fluorescent, HID or LED replacement, while the luminaire is the whole fixture. Lamps are named by shape and size codes: A19 is a standard household shape 19 eighths of an inch across, PAR38 a reflector lamp 38 eighths across, MR16 a 2 inch multifaceted reflector. Bulb also names the glass envelope, which is why pros avoid it for the whole lamp.
Order a case of PAR38 lamps, 3000 K, 25 degree, for the lobby track, and make sure they're dimmable.
Shape codes in eighths of an inch decode most lamp names: an MR16 is 16 eighths, or 2 inches, across the face.
Also heard as
- bulb
- light source
- globe
Related terms
Luminaire
The whole light fixture as one product: light source, optics, housing, driver or ballast and power connection.
LED
Light-Emitting Diode: a semiconductor light source, made white for lighting by coating a blue chip with phosphor.
HID
High-Intensity Discharge: lamps such as metal halide and high-pressure sodium that make light from an electric arc in a pressurized tube.
Ballast
The device that starts and limits current to fluorescent and HID lamps, which would otherwise draw unlimited current.