Lighting Glossary

Term	Description
Ballast	Current limiting device needed to run fluorescent, CFL and discharge lamps. Usually built into the fitting, or in the case of most CFLs, ballast and lamp are in one lamp-replacement unit.
BC	Bayonet cap, a push and twist connection on the base of a lamp. The standard size has a base of 22mm diameter, and these are sometimes known as BC22. See also Small Bayonet Cap / SBC
Bipin	2 pin bulb base used on fluorescent tubes and some halogen lamps
BL / blacklight	A lamp which produces UVA and blue/violet light
BLB / blacklight blue	Produces UVA only. The dark blue glass filters out nearly all the visible light.
Cap	The electrical connection end of a lamp.
Capacitor Ballast	A type of ballast used to eliminate strobing in workshops. Capacitor ballasts generally produces shorter tube life in most cases
Capacitor	Component used for power factor correction with magnetic ballasts.
Colour temperature	Informally a measure of light's perceived warmth or coldness. The temperatures are quoted in Kelvins (a change of 1 Kelvin is the same as a change of 1 degree Celsius, but the 0 point is "absolute zero" or approx -273 °C). As the temperature of an object increases, it will radiate electromagnetic energy. The amount of radiation and the frequency of it both increase with temperature. When hot enough it will start radiating energy in the visible light part of the spectrum - starting with a very dim red glow, moving through red hot, white hot, and eventually into a blue plasma phase. Confusingly, higher colour temperatures tend to be thought of as "cooler" light qualities. A Colour Temperature of 2700K - 3000K appears warm, 4000K - 5000K appears cold, and > 5000K is very cool or typically described as "daylight". The higher temperatures containing a higher percentage of blue light.
CFL	Compact Fluorescent Lamp.
Choke	Magnetic ballast used in glowstart fluorescent fittings.
Cool White	A lamp with a colour temperature typically in the 4000K to 5000K range - more blue than Warm, but not quite as blue as Daylight
CRI	Colour rendering index. How well light renders colours. One measure of light quality. 100 is perfect CRI, 50 is poor. CRI is not the only determinant of colour rendition, colour temperature matters too.
Daylight	Used to describe lamps with colour temperatures > 5000K. At very high levels of brightness daylight can create the effect of sunlight. At lower levels of brightness it is "colder" like the light on an overcast day.
Dimmer	A device for reducing lamp brightness. Note some lamp types (LED, CFL, Fluorescent) are incompatible with dimmers unless explicitly marked as "Dimmable".
Downlighter	fitting sending most light downwards
E14	a miniature Edison Screw fitting lamp base with a 14mm diameter
E27	The standard Edison Screw base with a 27mm diameter base, aka ES
E40	Giant Edison screw base, used with some discharge lamps. 40mm diameter
Efficacy	A measure of the output in lumens per watt. From a non-technical point of view can be considered as efficiency, although this is not strictly accurate.
ES	Edison screw cap
Fitting	The appliance the lamp fits into, often informally called a lamp, eg tablelamp.
Floodlight	produces a wide spread of light. Note some floodlights may look like spotlights, with a built in reflector.
Germicidal lamp	produces short wavelength germicidal UV. Damaging to eyes, kills bacteria & erases EPROMs. Never use these in insect killers or for parties. See UVC.
GLS	General Lighting Service, the traditional filament light bulb.
Halogen Lamp	Type of filament lamp with better efficacy than traditional filament lamps. Contains bromine or iodine. Very high capsule temperature.
Halophosphate	One of the 2 families of phosphorescent materials used in fluorescent tubes. Light output falls over time.
HID	High Intensity Discharge, aka metal halide lamp.
Lamp	lightbulb (not light fitting)
LED	Light emitting Diode. A small low power solid state light source.
Lumen	The SI unit for measuring the total quantity of visible light output from a light source
Luminaire	same as fitting
LV	Low Voltage - in the context of lighting, this typically refers to lamps run from 12V supplies.
Mercury Discharge Lamp	"Ice white" lamps used for street lighting, very energy efficient
Metal Halide	Lamp A high efficiency white discharge lamp
PAR	Parabolic Aluminised Reflector, a standard shape of spotlight lamp with a reflector built in. (Note LED versions are also now available)
Phosphor	Coating inside fluorescent tubes that transforms UV into visible light. See also: halophosphate, triphosphor
Plaster Uplighter	Plaster half bowl uplighter. Suffers various design defects.
Rough service lamp	Shock and vibration resistant filament lamp
SES	small edison screw, a miniature lamp base
Shelf fitting	The (normally fluorescent) fitting is mounted on its side on a shelf so the lamp is concealed from view. The fitting however remains visible.
Sodium lamp	Yellow lamps used for streetlighting
Spotlight	reflector lamp throwing most light out over a limited arc, producing a pool of light
Starter	small device that works with a magnetic ballast to start the lamp. Used with fluorescent and some discharge lamps. Starters may be glowstart, electronic, or rarely thermal or a manual switch.
Suntan Lamp	Lamp producing high levels of UVA. Protective goggles must be used.
T8, T12 T8	Designates the diameter of a tube in 1/8ths of an inch. Therefore T8 are 1" diameter fluorescent tubes, T12 are the older 1.5" diameter ones. T8s have mostly replaced T12s. T8s work happily in older T12 fittings.
Triphosphor	The more recent of the 2 families of phosphorescent materials used in fluorescent tubes. Slightly higher efficiency, less fall in light output over time.
Trough Fitting	The lamp is partially enclosed in a trough which conceals it from view. The fitting is also concealed.
Uplighter	Fitting sending most light upwards
UVA, UVB, UVC	The three frequency bands of ultraviolet. UVA is used for suntanning, blacklights and insect killers. Outdoor levels of UVA cause skin wrinkling and some cancers. UVB causes sunburn and cancers. UVC is germicidal and destructive to human tissue, and is not present in sunlight on earth. The wavelengths are approx: UVA: 320-400nm UVB: 290-320nm UVC: 200-290nm Around 2/3 of melanomas and 90% of basal and squamous cell skin cancers are currently attributed to UV exposure.
Warm White	Any lamp with a coulour temperature of around 2700K - intended to mimic the colour temperature of an incandescent lamp.

See Also

• Lighting
• Fluorescent Lighting
• LEDs
• Halogen Lighting
• Rewiring Tips