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Lighting Technical Terms

Technical Lighting Terms, What do They Mean?

What do all the technical lighting terms mean?


The lighting industry is not short of acronyms and technical terms all of which can make it quite confusing for non-lighting specialists. 

Have you ever replaced a bulb in a room and realised it generates light of a different colour than all the other bulbs in the room, or it doesn’t fit into the light fitting?

We’ll help you decipher some of the more common terms.


The technical measure of the amount of visible light emitted from a source. A lumen is the unit of luminous flux.  


Lux is the measure of the amount of luminous flux per area. One lux is equivalent to one lumen per square metre. Where lumens measure the brightness, or amount, of light, lux measures the intensity of light as it hits a surface. 

Colour Temperature:

Indicates how warm or cool light will appear to the human eye. Expressed in Kelvins, colour temperature is measured on a numbered scale, and describes the colour of light. The greater the Kelvin number, the cooler the light appears. 

The Colour Temperature Scale
The colour of light ranges from infrared to Ultra Violet, the more common domestic colours fall into the Warm White 2700k up to the Cool White around 6500k with Natural White falling in between around 4000-5000k.

The warmer white colours create a cosy atmosphere and are generally used in living areas whereas the natural or cool whites are more commonly used for task lighting.

Colour Rendering Index: 

This scale provides an assessment of how faithfully a light source can reveal an object’s colour when compared to the appearance of the colour under natural light. The CRI provides a quantitative measure which is particularly useful in certain settings, for instance, certain types of medical care or art restoration.



This is the abbreviation for the General Colour Rendering Index. The greater the RA number, the better the colour rendering of the light source. An RA of 100 is considered the same as natural daylight

Beam Angle: 

The beam angle determines how much of an area will be covered by light. Light sources tend to have different beam angles, meaning different amounts of light distribution, ranging from a very narrow coverage to a very wide distribution area. A normal bulb will have a beam angle of 360 degrees spreading its light to fill a room evenly whereas a downlight may only have a beam angle of 30 – 60 degrees meaning that more of the light produced is directional, similar to a torch.

CCT Settable GU10 LED Downlight
A Downlight projects its light in a specific direction within a certain Beam Angle.


LED stands for Light Emitting Diode. An LED is an electrical device that emits light when an electrical current flows through it in one direction. LED lighting is much more efficient than older-style incandescent bulbs. View our range of LED Lamps.

LED Lighting has to a large extent replaced older technologies such as Incandescent, Halogen and Compact Fluorescent owing to its efficiency and long life.


COB stands for Chip On Board. A COB light is a type of LED. COB technology combines many LED lights together to produce a COB light that is uniformly bright and powerful. 


Voltage is the measure of the force of electricity, measuring the output of electrical current. The greater the voltage, the greater the flow of electrical current.  Our domestic supply is normally 220-240 Volts AC.

AC stands for alternating current which alternates its direction of flow 50 times per second referred to as a frequency of 50Hz and DC stands for direct current which flows in one direction only.

Power Consumption: 

The power consumption of a device means the amount of power it will need to run. For lighting, this generally means the amount of electricity required. Normally measured in Watts or kilowatts for larger lights.

The greater the power consumption the more it will cost to run.


CFL stands for Compact Fluorescent Lamps. These are an energy-efficient alternative to the incandescent light bulb, using up to 70% less energy. 


Dimmable lights allow for fine-tuning of the lighting intensity by adjustment of the light beam.

Warm White: 

Warm White has a specific meaning on the Kelvin colour temperature scale. It refers to light bulbs with a colour temperature ranging from 2500K – 3000K, with a warmer, more yellow appearance. These lights are normally used in living areas for the relaxing and cosy light they emit.

Natural White: 

Natural White is another technical term from the Kelvin colour temperature scale. It refers to a colour temperature from 3300K – 5300K, giving a natural, neutral tone. Normally this colour of light is used for task lighting in kitchens and workshops.

Daylight Lamp: 

A daylight lamp is used to create a natural lighting effect at any time of the day. Daylight bulbs have a colour temperature that starts at 4600K and goes up to 6500K+.


A driver is an important component of an LED light. It is sometimes also called the PSU (Power Supply Unit), control gear, or ballast. Most LED lights require a different voltage or type of electricity from our domestic supply, a driver converts the 230V alternating current to a 12V direct current required by most LEDs.


This is a type of light bulb cap known as a bayonet cap, which you push and twist to fit. 

B22 LED Lamp
An Example of a B22 LED Lamp


This is the type of light bulb fitting also known as the Edison Screw. It screws in and is the most common type of light bulb fitting in the USA. E14 is a smaller size but quite a common connection type often used in table lamps and chandeliers.

e27 LED Bulb
An Example of an E27 LED Lamp


In lighting, efficacy is a measure of how much light a light source produces for the amount of energy put into it. Luminous efficacy is usually measured in lumens per watt.


Lighting efficiency means the ratio of luminous flux to wattage and gives a measure of whether a light requires a lot of energy to power it, or whether it is energy efficient. The greater the efficiency the cheaper it is to run the more you save on your electricity bill.

Electronic Transformer: 

An electronic transformer transfers electrical energy from one alternating-current circuit to another. They are a key component of most lighting systems, stepping down or stepping up the electrical current so that it can be used at the level required by the lamp or bulb.

Electronic transformers are smaller than their magnetic counterparts and can be reset at the wall switch if there is a system overload.

These are commonly used in domestic installation to convert 230Vac to 12Vac required for certain types of downlights.

Magnetic Transformer: 

Magnetic transformers perform the same function as electronic transformers. However, they do not have an inverter and are larger. They are also more durable than their electronic counterparts. 

Rated Lamp Life: 

This is a way of indicating the average lifetime of a light bulb. Also referred to as Average Rated Life, it is assessed by measuring the time it takes for half of a test sample of bulbs to die out, while the other half continues to burn. 

The older technology incandescent bulbs were rated for around 600 hours which equated to just a few weeks of day-to-day usage whereas the new LED technologies can last for many thousands of hours resulting in years of practical use.

IP – Ingress Protection: 

This is a way of measuring the durability of a light fitting. The IP rating of a light fitting consists of two numbers. The first indicates the standard of protection from solids, while the second shows how well the fitting is protected from water ingress.

The context of your lighting will determine what level of IP number you need, for instance, if you are lighting a bathroom or adding outdoor lighting to an area you will need strong IP to protect against the ingress of moisture. 

Older Light Technologies


The incandescent light bulb was the original light bulb to be invented. It works by heating a thin wire filament by passing an electrical current through it until it glows. Incandescent means light produced by heat radiation.


Halogen lighting is an enhanced version of incandescent lighting. The difference from incandescent bulbs is that a halogen bulb filament is housed in a quartz capsule that is filled with halogen gas. Halogen bulbs are more efficient and last much longer than standard incandescent bulbs. 


Fluorescent lighting is produced through a chemical reaction. Gases and mercury vapour interact inside a glass tube to produce an invisible UV light, which then illuminated the phosphor powder coating the inside of the tube. The whole tube then appears to glow. Fluorescent lighting is highly energy-efficient and cost-effective.

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