A-Z of Lighting Terms

A-Z of Lighting Terms

Aluminium reflector

Some flood lamps and spotlights have a thin piece of aluminium built into the inside of the glass casement. This aluminium reflector is used to ensure that heat and light is directed out of the light.



In a fluorescent lamp, the ballast is a fitting that regulates the flow of current.



Same as Cap.


Black Light Blue

A specialised fluorescent lamp that emits UV (ultraviolet) light.



A common name for an electric lamp. The name comes from the glass casement which is a feature of most bulbs / lamps.


Burning Position

This relates to the position in which lamps should be installed and / or operated. It can be denoted in codes such as p (horizontal), h (vertical base upwards) or s (vertical base downwards).



A measurement of luminous intensity, the candela (cd) allows us to compare light sources’ brightness directly.



Also known as a base, the cap acts as a fixture and electrical connection for a lamp. There is a wide range of fittings available for different lamps. This is important for safety, as it ensures that the right lamps and luminaires are matched. It also ensures that even though manufacturers have different types of lamps on offer, the caps are standardised in terms of the IEC 60061 standard.

Some of the better known caps for incandescent bulbs are:

B22d or BC- a 22mm bayonet fitting

ES – Edison screw


Colour Temperature

Colour temperature is considered in respect of the coolness or warmth of the light the bulb emits.

Take a look at sodium street lighting. It burns with an orange tone. Lamps that produce orange or yellow light are warm and have low colour temperatures.

We measure colour temperature in degrees Kelvin (K).


Guide to Colour Temperatures:

If the lamp has a colour temperature lower than 3,500K it is warm.


High pressure sodium lamps (2,000 to 2,200K)

Tungsten filament lights (2,700K)

Tungsten halogen lamp (3,000K)


If the lamp has a colour temperature between 3,500 and 5,000K it is cool

Example: Metal halide lamps (3,000 to 5,600K)


If the lamp has a colour temperature higher than 5,000K it is cold

Example: Daylight (5,500 t0 6,500K)


Chrome Cap

These incandescent lamps are designed with reflective coating in their glass. They are also known as crown silvered lamps. The reflective coating is used to direct most of the light in the direction of the light fitting.

Chrome caps were designed for use in spotlight fittings and were popular in displays in shop windows. Today they are used in modern light fittings as they can minimise glare and be used for attractive lighting effects.


Compact fluorescent

Compact fluorescents are considered as low energy bulbs, using the same technology as fluorescent tubes but the tubes are built in a much more compact manner.


Compact fluorescent tubes are popular because they offer:

- Reduced power consumption when compared to incandescent bulbs, generally around 80% less

- Longer life spans, generally 3 to 15 times more than incandescent bulbs

- Less heat emissions than incandescent bulbs. This means they can be used in enclosed fittings.


Compact fluorescents are divided into two groups:

Integrated: In an integrated compact fluorescent, the control gear and fluorescent tube are housed in one package. These can be used to replace incandescent lights and are manufactured with ES and BC fittings.

Non-integrated: With a non-integrated compact fluorescent, the control gear is included in the fitting and the lamp just consists of the folded tube. Historically these were used primarily in industrial and commercial applications but today they are being used in residential spaces, particularly for exterior lighting purposes.


Control Gear– For Fluorescent Lamps

Fluorescent lamps need specialised circuits to start them (starters). Then they need ballasts to restrict the electrical current once it has started running. This is known as the control gear. In most fluorescent fittings the ballast is incorporated into the fitting. The starter is usually a plug-in piece that can be easily replaced.

With electronic or high frequency fluorescent lights, the control gear needs an electric circuit to be able to do this. This enables the lamps to have quick switch-on, zero flickering and to operate more efficiently. There are some compact fluorescent fittings that have the circuit built into the lamp.

There is control gear available that enables fluorescent tubes to be dimmed.


Crown silvered

Same as Chrome Cap.



Meaning ‘two coloured’, cool beam or dichroic lamps are manufactured with a multi-layered coating on the lamp’s reflector. This allows the visible light to be reflected to the front while the heat is directed away to the back of the lamp.



In an incandescent lamp, the piece that glows when electrical current runs through it. In the first lamps, filaments were produced from carbon. Incandescent lamps being used today are primarily made of tungsten.


Fluorescent lamps

Fluorescent lights produce light by fluorescence. Fluorescence is the process of using a gas discharge to create ultraviolet radiation, and then using phosphor-coated glass to make it visible. By changing various coating materials, different colour temperatures can be created. The most common are daylight, cool white, white and warm white.

The diameter of the tube is measured in eighths of an inch.

Fluorescent tubes are popular because:

- They are energy efficient

- They have a long life span (usually more than 10,000 hours)

- They distribute light evenly.

In more specialised application, such as creating special effects in night clubs and for banknote forgery detection, fluorescent lamps can be manufactured using a blue black glass instead of fluorescent coating. This allows only the UV spectrum to be visible.

Fluorescent lights need starters and ballasts to work but they also function from the mains. The electronic control gear takes the mains power and turns it into a higher frequency. The ECG ensures less flickering, a quicker start, and more operating efficiency (which means loess power consumption).

Fluorescent lamps are available in a range of different shapes.



Same as tungsten halogen.


High frequency Fluorescents

Same as fluorescent lamps.


International Electrotechnical Commission (IEC)

The IEC is a worldwide body that develops international standards for the electrotechnical field. The IEC remains committed to maintaining the standards, assisting in the transfer of electrotechnology, encouraging fair international trade and helping with certification.



Most traditional lights are incandescent bulbs. They work with filaments (primarily tungsten wire) that are encased in glass. The filament glows when electrical current runs through it. An inert gas or a vacuum prevent the filament from burning.

Incandescent lamps are inefficient as most of the radiation available lies in the infra red spectrum, which means it is lost as heat rather than light. Most incandescent lamps produce warm lights, with colour temperatures in the region of 2,700K.



A light source is referred to as a lamp. Tubes, capsules, light bulbs and spots are kinds of lamps.



An LED or light emitting diode is a semi conductor. LED bulbs are popular because of their long life spans and energy efficiency, and are priced higher than incandescent and compact fluorescent lamps. LED life cycles far exceed those of any other light source. The degradation of LED chips will take place gradually over a period of 30 to 50 years.


Long life

Long life is a term applied to various lamps where higher quality components, construction techniques and manufacturing are employed. Long life lamps are also usually subject to more rigorous quality control standards.


Low Energy

Same as compact fluorescent.



Read the full article on a lumen here.



The luminaire is the fitting that the lamp is installed in. the luminaire will have a lamp holder that has the electrical connection in it. It can also include reflectors, shades and diffusers. It may have protective safety and decorative features too.


Metal halide lamps

These are discharge lamps with high pressure gas capsules that make an electrical arc inside them. These lamps generate stark white light, in a colour temperature range of 3,000 to 10,000K. they are used most often in showrooms, retails spaces and factories.



Same as control gear for fluorescent lamps.


Tungsten Halogen

These lights have quite a lot in common with incandescent lamps but they are filled with small amounts of halogens (like iodine, chlorine and bromine) as well as inert gases. They also use quartz for their lamp capsules instead of glass.

Tungsten halogen lamps are popular because:

- They have higher colour temperatures than tungsten incandescent lamps and generate bright light

- They are smaller than tungsten incandescent bulbs

- They have longer rated life spans that last between 2,000 and 5,000 hours.



The Watt is an international unit of measurement for power. It is named after James Watt, the man who invented with steam engine. In electric lamps the wattage relates to the power consumed, as well as the lamp’s brightness.