| Arc Tube |
A completely sealed quartz or ceramic tube where the electrical discharge (arc) occurs and light is generated |
| Ballast |
A device that, by means of resistance, inductance, capacitance or electronic elements, singly or in combination, controls the current, voltage and waveform to the required values for proper lamp starting and operation |
| Ballast Factor |
The ratio of the luminous flux of a lamp on a ballast at the rated supply voltage to the flux on a reference ballast |
| Color Rendering Index (CR1 or Ra) |
A measure of a light source's ability to render colors relative to a standard of 100 |
| Efficacy (Lamp) |
A ratio of lamp lumens to lamp power; measured in lumens per watt (LP ) |
| HID |
High Intensity Discharge lamps; includes metal halide, mercury vapor and high pressure sodium |
| High-Power-Factor (HP9 Ballast |
A ballast designed so that the input power factor is not less than 90% when the ballast is operated at the rated supply voltage using an appropriate reference lamp |
| Ignitor |
An electronic device which provides, by itself or in combination with other circuit components, the appropriate electrical conditions to start a discharge lamp |
| Initial lumens |
The light output of a lamp at rated power on a reference ballast after 100 hours of operation |
| Light Center Length (LCL) |
The distance from the center of the visible arc discharge to the bottom contact of the base |
| Lumens |
A measurement of light; takes into account the human eye sensitivity curve so that more weight is given to the yellow-green part of the light spectrum (photopic) |
| Lumen Maintenance |
The lumen output of a lamp at a given operating time or a percentage of 100 hour lumens at that time. |
| Lumens Per Waft (LPW) |
See Efficacy Maximum Overall Length (MOL): The maximum allowable distance from the top of the glass bulb to the end contact of the base |
| Mean Lumens |
Light output at 40% of rated lamp life |
| Open Rated Lamp (Medium Base) |
Designed for open luminaires; has a narrower neck than standard medium base lamps in order to fit into an exclusionary medium EX26 socket |
| Open Rated Lamp (Mogul Base) |
Designed with an extended contact pin on the bottom of the base; should be used with an open fixture mogul sockets (EX39) which prevents electrical contact if a non-C-rated lamp is used |
| Power Factor (Ballast) |
The ratio of the ballast input power (watts) divided by the product of the rms ballast supply voltage and ballast supply current |
| Pulse Start Lamp |
Specially designed metal halide lamp that requires a high voltage pulse for starting; has improved lumen maintenance |
