0ABCDEFGHILMPRSTV

0

0-10V dimming

A control method using a low-voltage signal pair from 0 to 10 volts to set brightness; it only sends commands, never reports back.

Also called: 1-10V, analogue dimming

A

Aventurine

Glass with tiny metallic crystals, usually copper, suspended in it to give a glittering effect. Making it needs a long, controlled cooling, which affects cost and lead time.

Also called: avventurina

B

Bathroom zones

Areas around a bath or shower, numbered by distance from the water, within which electrical equipment must meet minimum IP ratings and other rules.

Also called: Zone 0, Zone 1, Zone 2, BS 7671 Section 701

Binning

Sorting LEDs after manufacture into groups with very similar colour and brightness; poor binning gives patchy colour along a strip or between fittings.

Also called: LED binning, colour binning

BS 7671

The UK standard for electrical installations in buildings; it governs how fittings are fixed, wired, protected and tested on site.

Also called: IET Wiring Regulations, 18th Edition

BS EN IEC 60598-1

The general safety standard for luminaires, covering construction, marking, insulation, heat and mechanical tests. BSI lists the 2021 edition as current.

Also called: EN 60598, luminaire safety standard

C

Canopy (ceiling plate)

The cover at the ceiling end of a pendant or chandelier that hides the fixing and wiring; on heavy fittings the real fixing sits behind it.

Also called: ceiling cup, canopy

CE marking

The mark by which a manufacturer declares a product meets the law; in Great Britain UKCA applies, but CE has been accepted indefinitely for many product rules including low voltage equipment.

Also called: UKCA marking, conformity marking

Ceiling rose

A small accessory that connects a pendant's flex to the ceiling wiring; ordinary roses are rated for light fittings only and are not designed for heavy chandeliers.

Also called: ceiling pendant set

Chandelier

A decorative fitting hung from the ceiling with several arms or tiers carrying lamps. In Approved Document L, chandeliers are treated as art objects with integral lighting.

Also called: pendant chandelier

Chandelier winch

A manual or motorised hoist that lowers a heavy fitting to floor level for cleaning and re-lamping.

Also called: lowering gear, chandelier hoist

Circuit-watt

The electrical power drawn by lighting circuits for the light sources plus their drivers and any power-factor correction, used when Part L measures lighting efficiency.

Also called: circuit watts

Colour rendering index (CRI, Ra)

A score out of 100 for how faithfully a light shows eight standard pastel colours compared with a reference source. It ignores strongly saturated reds, which is why R9 and TM-30 are also used.

Also called: CRI, Ra

Colour temperature (CCT)

A number in kelvin describing how warm or cool white light looks; lower numbers such as 2200 to 2700 K look warm and yellow, higher ones look cool and blue.

Also called: correlated colour temperature, kelvin, warm white

Containing product

A product that has light sources or control gear built in, such as a luminaire or a piece of lit furniture. UK lighting regulations require those parts to be replaceable and documented.

Also called: product containing light sources

Cord (in glass)

A thin, glassy streak or ripple inside a piece where glass of slightly different density has not mixed fully; common and often acceptable in handmade glass.

Also called: stria, striae, ream

Cristallo

The clear, colourless Venetian glass perfected in the 15th century, made soda-lime based rather than with lead. It is not the same as lead crystal.

Also called: cristallo glass

Critical location (glazing)

Zones of doors, side panels and windows near the floor or door where glazing is most likely to be hit, so Part K requires it to be safe breaking, robust or protected.

Also called: critical locations

Crystal glass (cristallin)

A lower category that must contain at least 10 per cent of zinc, barium, lead or potassium oxides (singly or together) and meet minimum density and refractive-index values. Marketing uses 'crystal' loosely, so the label alone proves little.

Also called: crystalline, crystal

D

DALI

A digital lighting control standard in which each fitting has an address on a shared two-wire bus, allowing individual control and feedback.

Also called: DALI-2, IEC 62386, Digital Addressable Lighting Interface

Declaration of Conformity

A signed statement from the manufacturer or importer listing the laws and standards a product meets; the document to request with each luminaire.

Also called: DoC, EU declaration of conformity

Dim-to-warm

An LED fitting that becomes warmer in colour as it is dimmed, imitating the behaviour of a filament lamp.

Also called: warm dimming, warm dim

Display lighting

In Approved Document L, lighting to highlight exhibits or merchandise, or lighting used in public leisure spaces such as restaurants, dance halls, auditoria and cinemas.

Also called: accent lighting (Part L)

Driver (LED)

The electronic unit that converts mains to the controlled current or voltage an LED needs; it is also the part that most often fails and the part dimming compatibility depends on.

Also called: LED power supply, control gear, transformer

Drop (suspension length)

The length from the ceiling fixing to the lowest part of the fitting, which determines how far it hangs.

Also called: overall drop, hanging length

E

Ecodesign (lighting products)

UK rules on the energy performance, information and replaceability of light sources and control gear, in force since 2021.

Also called: Lighting Products Regulations 2021

Embodied carbon (luminaires)

The carbon emitted making and delivering a product. CIBSE TM65 gives a calculation method for building services, and TM65.2 applies it to lighting.

Also called: TM65, TM65.2

Emergency lighting

Lighting that comes on when the normal supply fails; escape lighting is the part that lights the way out. It is separate from decorative lighting.

Also called: escape lighting, BS 5266-1

Environmental Product Declaration (EPD)

A standardised, verified document reporting a product's environmental impacts over its life.

Also called: EPD

F

Filigrana

Murano canework in which thin glass rods with white or coloured threads are fused and blown into delicate lattice or twisted patterns; reticello and zanfirico are specific forms.

Also called: filigree glass, reticello, zanfirico

Flicker

Rapid brightness variation that can be seen, or felt, or show up on camera; Pst LM and SVM are the two standard measures of how visible it is.

Also called: stroboscopic effect, Pst LM, SVM

Free-blown glass

Glass shaped by a glassmaker blowing and tooling a gather of molten glass without a mould, so each piece differs slightly.

Also called: hand-blown glass, mouth-blown glass

Full lead crystal

The top category of crystal in the Council Directive, with at least 30 per cent lead oxide and a higher minimum density than lead crystal.

Also called: cristal supérieur, 30% lead crystal

G

Gilding

Applying very thin sheets of gold or other metal leaf to a prepared surface; water gilding is burnished and refined, oil gilding is tougher but less brilliant.

Also called: gold leaf, water gilding, oil gilding

H

Heat-soaked glass

Toughened glass held in a hot chamber to break pieces carrying a rare internal flaw (nickel sulphide), cutting the chance of spontaneous breakage later.

Also called: heat soak test

I

IK rating

A scale from IK00 to IK10 showing how much impact a fitting's enclosure withstands.

Also called: impact protection rating

Incalmo

A technique that joins two separately blown pieces of different colours at their rims to make a single vessel with distinct bands of colour.

Also called: incalmo technique

IP rating

A two-digit code showing how well an enclosure resists solid objects (first digit) and water (second digit); decorative glass fittings are usually only IP20, meaning dry interiors.

Also called: ingress protection, IP44, IP65, IPX4

L

L70

The time at which an LED has dropped to 70 per cent of its original light output; B50 means half of a batch will have done so by then. Neither is a guarantee of life.

Also called: B50, lumen maintenance

Lacquered brass

Brass sealed with a clear coating to stop it tarnishing; the coating can wear or yellow, especially in high-touch or humid places.

Also called: clear coated brass

Laminated glass

Two or more glass layers bonded with an interlayer that holds the pieces together when broken.

Also called: safety laminate

Lamp

The replaceable light-producing part, such as an LED lamp or filament lamp. Regulations now tend to say 'light source'.

Also called: bulb, light source

Lamp base (cap)

The standard fitting at the end of a lamp. E14 (small Edison screw) is common in chandeliers, E27 is the larger screw, G9 is a small pin type, and GU10 is a spotlight twist-lock.

Also called: E14, E27, G9, GU10, B22

Lattimo

An opaque white glass; in lighting it diffuses the lamp so there is no visible source.

Also called: opal white glass, milk glass

Lead crystal

Glass containing at least 24 per cent lead oxide and meeting a minimum density, which is what UK and EU rules allow to be sold as lead crystal. It is heavier and more brilliant than ordinary glass.

Also called: lead glass, 24% lead crystal

Leading-edge dimmer

A mains dimmer that cuts the front of each AC wave. It suits filament and halogen lamps but can make some LED drivers buzz or flicker.

Also called: TRIAC dimmer, forward-phase dimmer, phase-cut dimming

LENI

A measure of a lighting scheme's annual energy use per square metre, offered in Part L as an alternative to the simple efficacy test.

Also called: Lighting Energy Numeric Indicator

Light source lumens

The combined average initial light output of all the light sources in a fitting, before any losses in the fitting itself.

Also called: lamp lumens

Living finish

A metal finish left unsealed so it changes colour with handling and time, as opposed to a lacquered one that stays as made.

Also called: unlacquered brass, patina finish

LOLER

UK regulations requiring that lifting equipment used at work, which can include chandelier winches, is properly planned, installed, examined and recorded.

Also called: Lifting Operations and Lifting Equipment Regulations 1998

Low-iron glass

Glass with less iron so it lacks float glass's green tint; used where colour accuracy matters, such as edge-lit shelves.

Also called: extra-clear glass, optiwhite (brand)

Lumen

A measure of the total visible light a source produces, regardless of direction.

Also called: lm, luminous flux

Luminaire

The complete lighting unit, including the housing, optics and electrical connections, that holds and controls one or more light sources.

Also called: light fitting, lighting fitting, fixture (US)

Luminaire efficacy

How much light a fitting delivers for the electrical power it uses, expressed in lumens per circuit-watt; Part L sets minimum values for general and display lighting.

Also called: lumens per circuit-watt, lm/W

Luminaire lumens

The light that actually leaves the fitting: the light-source output multiplied by the fitting's light output ratio.

Also called: output lumens

Lux

How much light falls on a surface, measured as lumens per square metre; it is what lighting-level recommendations are written in.

Also called: lx, illuminance

M

Murano glass

Glass made by workshops on the island of Murano in the Venice lagoon, usually hand-worked from soda-lime glass using techniques developed over centuries. Not every piece sold as 'Murano' was made there.

Also called: Murano art glass, Venetian island glass

Murrine

Slices of patterned glass canes arranged and fused into a surface, giving a mosaic effect; millefiori is the familiar flower-patterned type.

Also called: murrina, millefiori

P

Pendant

A fitting hung on a cable, cord, chain or rod, usually with a single shade or light source, as distinct from a multi-arm chandelier.

Also called: suspension light, hanging light

Pontil mark

The rough scar left on a hand-blown piece where the glassmaker's rod was attached, usually ground or polished. Retailers treat it as a sign of hand-making, though a smooth base proves nothing either way.

Also called: punty mark

Promovetro

The consortium of Murano glass producers that administers the Vetro Artistico Murano mark on behalf of the Veneto Region and polices its use.

Also called: Consorzio Promovetro Murano

Protection class (I, II, III)

A classification of how a luminaire protects against electric shock: Class I relies on an earth connection, Class II on double or reinforced insulation, and Class III on safe extra-low voltage supply.

Also called: Class I luminaire, Class II, double insulated

PVD finish

A thin, hard metallic coating deposited in a vacuum, used for durable brass, bronze and black finishes on steel or brass.

Also called: physical vapour deposition

R

R9

The colour rendering score for saturated red; it matters for skin tones, wood, leather and food, and can be low even when overall CRI is high.

Also called: R9 value

Rezzonico

A classic Venetian chandelier style with many glass arms, leaves, flowers and cups on a central stem, named after the Ca' Rezzonico palace. In trade use it describes the form, not a maker.

Also called: Ca' Rezzonico chandelier, Rezzonico style

S

Safe breakage

Glazing that, when broken in an impact test, leaves only a small opening, disintegrates into small particles or breaks into pieces that are not sharp.

Also called: safe-break glazing

Sconce

A fitting fixed to a wall, often a decorative one; the term is used mostly for candle-style or ornate wall lights.

Also called: wall light, wall bracket

SDCM

A measure of how closely light sources match in colour; fewer steps (such as 3) mean fittings look the same when installed side by side.

Also called: MacAdam ellipse, MacAdam step, standard deviation of colour matching

Seed (bubble)

Tiny air bubbles trapped in glass; common in handmade pieces and usually judged by size and number against an agreed standard.

Also called: air bubble, gaseous inclusion

SELV

A low-voltage supply, kept separate from the mains and earth, designed so that touching it cannot cause a dangerous shock.

Also called: safety extra-low voltage, 12 V lighting

Sommerso

A Murano technique where one colour of glass is encased inside a thicker layer of another, giving deep, layered colour.

Also called: submerged glass

Specialist process lighting

In Approved Document L, lighting that serves a specialist task rather than lighting the space itself, including theatre spotlights, illuminated signs and art objects with integral lighting such as chandeliers.

Also called: specialist lighting

T

TM-30

A newer colour-quality method from the Illuminating Engineering Society that reports fidelity (Rf) and gamut (Rg), showing how a light changes colours rather than giving one score.

Also called: IES TM-30, Rf, Rg

TM66

CIBSE guidance on assessing how repairable and recoverable a luminaire is, with two tools: CEAM-Make for manufacturers and CEAM-Specify for quick comparison by specifiers.

Also called: CEAM, circular economy assessment method

Toughened glass

Glass heat-treated so it is several times stronger than ordinary annealed glass and breaks into small dice-like pieces.

Also called: tempered glass

Trailing-edge dimmer

A mains dimmer that cuts the end of each AC wave; usually quieter and a better match for electronic LED drivers, but the driver must support it.

Also called: reverse-phase dimmer, ELV dimmer

Tunable white

A fitting with two LED colours that allows the user or control system to choose any colour temperature across a range, independent of brightness.

Also called: CCT tuning, two-channel white

V

Venetian glass

A looser term for Venetian-tradition glass, often made on the mainland rather than on Murano and with no legal protection. A retailer article we read separates this from island-made glass.

Also called: Venetian-style glass, Venetian chandelier glass

Vetro Artistico Murano mark

A collective origin mark, set up under Veneto regional law, that shows a piece was made on Murano by a licensed producer. It proves where the glass was made, not that it is lead-free, high quality or electrically certified.

Also called: Vetro Artistico Murano trademark, Murano origin label, Murano glass trademark