Bus
Ballast
Ballast Factor (BF)
Base or Socket
Bi-Pin Base
Base Temperature
Bayonet
Current Type (AC/DC)
Alternating Current (AC)
Direct Current (DC)
Circuit
Connector
Dimmer, Dimming Control
D/A Converter
Analog Signal
Digital Signal
Efficacy
Efficiency
Frequency
Hot Restart Time
Ignitor/ Starter
Instant Start/ Rapid Start
Lighting System
Operating Position or Burn Position
Power Factor (PF)
Preheat Circuit
Response Time
Self-Ballasted Lamps
Starting Temperature (Minimum)
Total Harmonic Distortion (THD)
Warm Up Time (to 90%)


Bus
A complex wiring system, mostly consisting of a conductor to which other electrical devices are connected. Buses are often used in power distribution equipment to handle large amounts of electrical current like panelboards.

Ballast
A device used to start and operate lamps. High intensity discharge and fluorescent lamps require this device to start and control the inrush current. Ballasts are driven by some additional current beyond what the lamp needs. The total wattage of the fixture is more than the wattage of the lamp(s) within it.
Class "P" Ballasts contain a thermal protective device which deactivates the ballast when the case reaches a certain critical temperature. The device resets automatically when the case temperature drops to a lower temperature.


Ballast Factor (BF)
This is the percentage of a lamp's rated lumen output when operated with a ballast. A ballast factor of 0.93 will result in the lamp emitting 93% of its rated lumen output. A ballast with a lower Ballast Factor (BF) results in less light output.

Base or Socket
The base is the end of the lamp that fits into the socket. The socket is the receptacle connected to the electrical supply. There are many types of bases used in lamps, screw bases are the most common ones for incandescent and HID lamps, while bi-pin bases are common for linear fluorescent lamps.
Bi-Pin Base
Any base with two metal pins for electrical contact. This is the typical base for a fluorescent tube. It consists of two prong contacts which connect the fixture.

Base Temperature (Maximum)
The maximum operating temperature permitted for the base in Celsius. Fixture manufacturers need to ensure that these conditions are realized in their fixtures.

Bayonet
A style of bulb base which uses keyways instead of threads to connect the bulb to the fixture base. The bulb is locked in place by pushing it down and turning it clockwise.

Current Type (AC/DC)
Whether the operational voltage is based on Alternating Current (AC) or Direct Current (DC).

Alternating Current (AC), the flow of electric charge periodically reverses direction.

Direct Current (DC) is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, solar cells and dynamo types.

Circuit
A complete electrical path leading from an electrical supply through conductors and perhaps dimmers, distribution equipment, electrical devices, electronic items and maybe more devices to the load and returning to the source.

Connector
Connector is the name for a family of electrical wiring devices, such as plugs and receptacles comprising one or more contacts. Generally, any item used to make an electrical connection between two or more separate conductors.

Dimmer, Dimming Control
A device used to lower the light output of a source, usually by reducing the wattage it is being operated at. Dimming controls are increasing in popularity as energy conserving devices.

D/A Converter
Digital-to-Analog Converter is an apparatus that converts digital signals to analog signals.

Analog Signal
An analog signal is a continuous signal where the amplitude or frequency of the voltage respectively current takes any value within a range of values. An analog signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity.

Digital Signal
A digital signal is a physical signal that is a representation of a sequence of discrete values, for example of a bit stream, or of a digitized analog signal.

Efficacy
A measurement of how effective the light source is in converting electrical energy to visible light. Expressed in lumens-per-watt (lm/W).


Efficiency
The efficiency of a light source is simply the fraction of electrical energy converted to light. For example, a 100W incandescent lamp converts 7% of the electrical energy into light. The efficiency of the luminaire or fixture is the percentage of the lamp lumens that are emitted by the fixture.

Frequency
The operating frequency in Hz of a lamp. Frequency, measured in Hertz (Hz), equals the number of waves that passes a given point per second.
Line voltage and frequencies of different regions:
USA 120V AC/ 60Hz or 277V/ 60Hz
UK and Australia 240V AC/ 50Hz
Europe 230V AC/ 50Hz

Hot Restart Time
Time it takes a High Intensity Discharge lamp to reach 90% of its light after On-Off-On cycle.

Ignitor/ Starter
An electronic device providing a high voltage pulse to initiate an electrical discharge, typically paired with or part of the ballast.

Instant Start/ Rapid Start
A type of ballast designed to start fluorescent lamps as soon as power is applied. Most T8 fluorescent lamps are operated on electronic instant-start ballasts. Slimline fluorescent lamps operate only on instant start circuit.

Lighting System
A term referring to the lamp and ballast combination, and sometimes to the entire lighting delivery system including the fixture, the optics, the particular layout and the lighting controls.

Operating Position or Burn Position
Mercury and High Pressure Sodium lamps may be operated in any burn position and will still maintain their rated performance specifications. Metal Halide and Low Pressure Sodium lamps are optimized for performance in specific burn positions, or may be restricted to certain burn positions for safety reasons.

Power Factor (PF)
A measurement of the phase difference between voltage and current drawn by an electrical device, such as a ballast. Power factors can range from 0 to 1.0, with 1.0 being ideal. Power factor is sometimes expressed as a percentage. Incandescent lamps have power factors close to 1.0 because they are simple "resistive" loads. The power factor of a fluorescent and HID lamp system is determined by the ballast used. "High" power factor usually means a rating of 0.9 or greater. Since volts and watts are usually fixed, amperes (or current) will go up as power factor goes down. This necessitates the use of larger wire sizes to carry the increased amount of current needed with Lower Power Factor (LPF) ballasts. The addition of a capacitor to a LPF ballast converts it to a High Power Factor (HPF) ballast, which also called power factor correction (PFC).

Preheat Circuit
A type of fluorescent lamp-ballast circuit used with the first commercial fluorescent lamp products. A push button or automatic switch is used to preheat the lamp cathodes to a glow state. Starting the lamp can then be accomplished using simple "choke" or reactor ballasts.

Response Time
The time it takes for a dimmer to reach its intended level from the initiation of an input control signal. Furthermore, the time it takes a lamp filament to react to a change in voltage.

Self-Ballasted Lamps
A discharge lamp with an integrated ballast allowing the lamp to be directly connected to a socket providing line voltage (like CFL and some LED lamps).

Starting Temperature (Minimum)
The minimum ambient temperature at which the lamp will start reliably.

Total Harmonic Distortion (THD)
A measurement of the distortion caused by ballasts and other inductive loads of the input current on alternating current (AC) power systems caused by higher order harmonics of the frequency (60Hz in North America). THD is expressed in percentage and refers to electrical loads (such as ballasts) or a total electrical circuit or system in a building. THD is recommended not to exceed 32% for electronic ballasts. Excessive THDs on electrical systems can cause efficiency losses as well as overheating and degradation of system components.

Warm Up Time (to 90%)
The time it takes for a High Intensity Discharge lamp to reach 90% of light output after being turned on.