To guarantee the best performance from an LED efficient heat dissipation is essential. LED's only convert about 25% of the electricity they consume into visible light. The rest of the power is converted into heat energy which must conducted away from the LED and dissipated into the atmosphere. This unwanted heat if not managed correctly will destroy the LED resulting in greatly reduced lifespans as well as lower efficiency and reliability.

There are 2 main techniques used to remove heat away from LED's. Active and passive cooling.

Passive cooling is the most common using finned heat-sinks made from cast or extruded metal. These types do not suffer from performance degredation over time and do not make any noise.

Active cooling types are less common. They include fan and liquid cooling and are capable of dissipating larger amounts of heat, however they generally produce noise, are more expensive and suffer from performance degradation over time.

An optimal thermal management system is an primary requirement in LED solid-state lighting (SSL) lamps and luminaires in order to deliver long lifespans and consistent color and lumen outputs. Realizing such an optimal design starts in the engineering lab with accurate models and design simulations, includes correct selection of thermal products such as heat-sinks, and continues through to a robust manufacturing plan. 

Low power consumption

  

Dimmable

LED is dimmable as long as the LED lamp or fittings driver circuit is of a dimmable type (refer to Dimming LED). Although halogen & incandescent are easily dimmable, fluorescent, mercury vapour, matal halide & high pressure sodium are not.

  

Higher efficiency

LED wastes far less energy in the form of heat than traditional lighting types. LED= 50lm/W, incandescent= 15lm/w. Despite this LED is only about 10% efficient. Haitz law predicts that the efficiency of LED will double once every 3yrs & to date this has proved to be true.

 

No UV or IR spectrum emitted

Because LED doesnt emit light in the UV or IR spectrum it attract far less insects. These wavelengths of light are also wasted energy as they can't be seen by the human eye.

High CRI

CRI is the ability of the light to accurately represent the object being illuminated. LED generally has high a CRI (>90CRI). Cheap ebay LED usually doesn't. Halogen & incandescent have high CRI (>90CRI) but fluorescent lighting CRI is very low (>70CRI).

Reduced maintenance costs

Everytime a light is relamped it will cost between $5 & $10 in labour plus the cost of the new lamp. A halogen or incandescent lamp will be relamped approximately 25X over the lifespan of just one LED lamp! Also because LED are solid state & have low operating temperatures they are far less prone to decay or breakage. The failure rate of LED is also very low & is ±1% within its expected lifespan.

 

Instant start time & ability to cycle on/off

The ability of LED to switch instantly makes it perfect for use as security lighting with a sensor. Unlike Fluoro/MV/HPS/ MH which require a warm up time in the range of 5-10 minutes.

 

Shock & vibration resistant. (solid state) 

LED are solid state devices which means they are very robust. As they dont have a filament like halogen or incandescent they can handle a drop. 

Low operating temperature

The operating temperature of LED is between 20º-40º, this is because LED is very heat sensitive. A heatsink is used to dissipate the heat created at the LED's junction which is the place where the light is produced. If they are allowed to overheat it will greatly reduce their lifespan but this also makes them a very low fire risk.

Any colour in the visual spectrum

LED can be any colour in the visual spectrum. There by adding various compounds to the diode during production a LED can be any colour desired. The other way to achieve this is by colour mixing the 3 primary colours of light. By varying the levels of red, green & blue light in a fixture we can achieve any colour in the spectrum. 

   

Control gear/power supplies draw & therefore cost less

Regulated DC power supplies are ±98% efficient. Compare this to the old heavy wire wound downlight transformers or fluorescent ballasts which are <90% efficient & will over time add up to the cost of a LED lamp in wasted energy.

Ability to focus light with a lens

Because LED light is emitted from a single point source it is much easier to focus its beam with a lens. This is a more efficient & more compact way than the alternative which is to use a reflector.

 

Small physical size

LED's are small in size which enables them to fit in places that others can't. A notable example is the LED flexible tape which is replacing fluorescent tubes used in pelmet lighting. Where the fluorescent used to stop shy of corners because of its fixed tube size the flexible tape can be cut every 50mm to get to the corners. It can be used on a curved section unlike the fluorescent & will also be free from the gaps of light seen where the fluorescents butted together thus providing even & consistent light.

 LED -

Higher initial price
Although the initial cost of LED is high, you're investment can be recouped 20X over time in energy savings & reduced maintenance costs. This makes LED the cheapest lighting available.

Effected by temperature
Keep the ambient operating temperature under 50º or lifespan is reduced. Be careful of installing LED in extremes like direct sunlight or surrounding it in thermal insulation where heat cant dissipate. Install a sunset switch if your LED is exposed to direct sunlight, this will ensure the LED is protected during the day when the light isn't required.

Voltage sensitive
LED's are highly sensitive to voltage fluctuations & can blow instantly with overvoltage of even 1 or 2 volts. Always use the correct voltage. Using a regulated power supply for low voltage LED will ensure that the voltage will never exceed the operating voltage 

Colour correction
At around ±2000hrs LED will warm. Although the effect is mostly negligible the cheaper ebay LED can warm by as much as a few 100 kelvin.

Gradual dimming
LED will gradually dim over time as it reaches the end of its life. This happens in the last 10000hrs & is instead of the instant blow that occurs with filament lamps. This can be as positive as it can give you ample time to  prepare for a relamp.
 

Beware of cheap LED
Buyer beware! With LED you really do get what you pay for. Cheaper LED like a lot of the stuff sold on ebay can have all sorts of potential problems. Poor CRI, incorrect colour temperatures are a few of the things to watch out for. Overdriving the LED to boost initial performance can be paid for with greatly reduced lamp life.

If you want to convert your existing mains powered lighting to LED then it should just be a matter of changing the globes for LED's with matching specs. It's also be a good opportunity to look at what you currently like & dont like about your existing lights & make the necessary changes. One problem you may encounter is the LED lamp is not as bright as the lamps you're replacing. The brightest of LED globes are currently only as bright as a 60W incandescent for the same size package. Maybe you'll have to add extra lights to the room to compensate or maybe the room is overlit anyway. Either way this is a limitation of LED that must be considered.

If you have dimmable mains powered lights & want to retain that function, you must make sure you replace them with dimmable LED. It is hard to say whether your dimmable LED lamps will work with your existing dimmers until you try them. Some retailers will list their lamps dimming compatibility with common dimmer types & it may require paying a electrician to fit a dimmer thats compatible. If youre existing dimmers aren't compatible don't worry they're unlikely to damage the LED. Instead they'll probably just strobe or pulse at certain points on the dimming dial.

Converting Low Voltage Lighting such as MR16 Downlights to LED 

MR16 lamps all have a transformer that steps the voltage down from mains power 240V AC to 12V AC most commonly. The LED itself only operates on DC & unless the electronics within the lamp have a rectifier that will convert the AC from these transformers then they wont work & even then it can still be problematic

The best option when retrofitting downlights for LED is to replace your existing AC transformers with regulated DC power supplies. This can be either one per light, or if the wiring is easily accessible a electrician can rewire for one power supply per switched group of lights. This will need to be done if you want to use a dimmable MR16 as the dimming is done on the secondary load side of the transformer with a LED dimmer. 

Another option when retrofitting MR16 is to change to a GU10 style LED lamp which works of mains power & can be dimmed with a mains voltage dimmer (refer to dimming LED). Retrofitting is then simply a case of cutting the 240V lead that supplied the transformer & fitting a GU10 lampholder in its place. This will also save you the expense of the additional power supply as the GU10 lamps has a built in power supply & is generally the same price.

If you want to try to reuse your existing AC transformers, here's what you should know.

The older style transformers are heavy wire wound induction devices which are generally compatible & will even dim a dimmable LED. However they are highly inefficient & outdated pieces of technology & it is recommended that you replace them. The losses from the transformer can be more than the wattage of the lamp. There can also be other problems such as buzzing & flickering with cheaper LED.

The other style of existing transformers you'll encounter are electronic. These have a minimum operating wattage which is usually higher than the wattage of a LED lamp & therefore wont work with one lamp alone. They can also tend to be very hit & miss & in our testing have generally been found to be incompatible with LED. Remember the LED runs on DC & needs a inbuilt rectifier to handle a AC voltage.

CRI stands for Colour Rendering Index which is the objective scale used to represent light quality. It represents the ability of a light source to faithfully reproduce the various colours of a object in comparison to natural sunlight.

Sunlight has a CRI of 100, halogen & incandescent rate highly at >90CRI whilst fluorescent rates poorly >70CRI. When it comes to LED there can be big differences in CRI. A quality LED lamp will have a CRI >90, then theres the ebay LED which can be 50-60CRI. which unfortunately you wont discover till you install them. 

The image to the right is a example of the CRI difference between quality & cheap LED. Daylight is top, a CREE LED middle & a cheap ebay LED bottom. The ebay LED shows us a dull & lifeless view of the object whilst the CREE LED gives us a accurate view & is hard to distinguish from the daylight.

Can you can imagine how a low CRI light would make your home look!

If you are trying to determine how bright a light is in comparison to another, then compare the lumen output. This is also known as luminous flux & is measured in lumens (lm).

Luminous flux is the total light output from a source, regardless of the direction the light travels. 1 lumen is equivalent to 1 candlela & this also the power emitted from 1 candle. A candela is the unit of luminous intensity in a particular direction.

Brightness is simply a subjective measure of luminous flux.

Lux (lx) is the level of brightness that falls at a particular point & distance. 1 lux is equivalent to 1 lumen per square meter & can be calculated as (lm/m²). So if you had 300 lux at 3m height, then there is 300 lumens of light per square meter at that particular height. For offices & work areas this is approximately the lux level required for sufficient lighting. 

These lights and globes are most commonly dimmed using a phase control dimmer of which there are of 3 types. Leading edge, trailing edge & universal dimmers.

These dimmer types cut off sections of the sine wave and reduce the power the light receives. Leading edge cuts the leading edge of the sine wave, whilst trailing edge cuts the trailing part of the sine wave. 

The electronic circuit in the LED lamp or external LED transformer can read the change in the sine wave pattern from the dimmer and will adjust the forward current supplied to the LED which in turn increases or reduces the light output.

A dimmable LED will need to be tested with a specific dimmer to know whether it is compatible or not & one can not assume if a LED works with one type of leading/trailing edge dimmer that it will work with another.

Dimming ELV LED Lights Like MR16 LED Downlights

The best way to dimm 12V or 24V LED is with a low voltage dimmer fitted on the secondary side of the transformer. This is a purpose built LED dimmer which uses pulse width modulation (PWM) to dimm the LED. PWM works by rapidly switching the supply on & off at very high frequency.

Note: The dimmer can be removed from its casing & mounted on most standard switch plates.

It is possible to dim 12V LED downlights using existing halogen transformers & mains powered dimmers but it is not advised as they are highly innefficient & outdated devices.  Flickering, humming, and higher output at certain dimmer levels can also occur.

The standards method for testing the light output and light distribution of LED lighting fixtures.

AMCA

The Australian governing body for EMC compliance & responsible for the C-tick.

additive color model

A type of RGB color model that describes how different proportions of red, green and blue light combine to create colors. In the additive color model, combining red, green and blue light in equal amounts produces white light.

AllnGaP

The aluminum indium gallium phosphide material system for manufacturing red and amber high-brightness LEDs.

ballast

Induction circuitry that regulates current for fluorescent lamps and HID lamps. The newer ballasts are electronic & incorporate a starter circuit also. 

binning

The general term for the production and sorting methods used by LED makers to ensure that the LEDs they manufacture conform to stated specifications for forward voltage, color and luminous flux. The poorer quality diodes are then sold to lamp manufacturers which are commonly found on ebay!

brightness

The subjective impression of the intensity of a light source. Often used incorrectly as a synonym for luminous flux, an objective measurement of the visible power of a light source.

candela

The standard unit of luminous intensity, the power emitted by a light source in a particular direction, weighted by the spectral luminous efficiency function.

C-Tick

A regulatory marking usually followed by a “N” number relating to the suppliers declaration of conformity to relevant EMC standards.

CCT

See correlated color temperature

CFL

See compact fluorescent lamp

chromaticity

An objective specification of the quality of a color, independent of its luminance and as determined by its saturation and hue.

color rendering index (CRI)

The standards unit of luminous intensity-power emitted by a light source in a particular direction, weighted by the spectral luminous efficiency function.

color temperature

See correlated color temperature

compact fluorescent lamp (CFL)

A type of fluorescent lamp with relatively low power draw, often designed to replace an incandescent lamp.

controller

A device that controls the output of color-changing and tunable white lighting fixtures. Controllers typically have software components for configuring fixtures and designing and editing light shows, and hardware components for sending control data to fixtures.

correlated color temperature

Describes whether white light appears warm (reddish), neutral or cool (bluish), based on the appearance of light emitted by a black body heated to various temperatures in degrees Kelvin (K).

CRI

See color rendering index

DALI

See digital addressable lighting interface

delivered light

The amount of light a lighting fixture or lighting installation delivers to a target area or task surface, measured in footcandles (fc) or lux (lx).

digital addressable lighting interface

A digital communications protocol for controlling and dimming lighting fixtures, originally developed in Europe.

DMX

A digital communications protocol for controlling lighting fixtures, originally developed to control stage lighting. DMX is one way data packet communication & is very quick.

efficacy

This is the energy efficiency of a lighting fixture and is the amount of light produced (in lumens) per unit of energy consumed (in watts) or lm/W. Not to be confused with luminous efficiency.

energy efficiency

See efficacy

forward voltage

Occurs when a negative charge is applied to the n-type side of a diode, allowing current to flow from the negatively-charged area to the positively-charged area.

heat sink

A feature of device that conducts or convects heat away from sensitive components, such as LEDs and electronics. Normally made from metals with heat conductive properties such as aluminium or copper they can also be ceramic.

HID lamp

A type of electrical lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube.

illumimance

The intensity of light falling on a surface area. If the area is measured in square feet, the unit of illuminance is footcandles (fc). If measured in square meters, the unit of illuminance is lux (lx).

illuminator-type LEDs

High performance, high-power LEDs capable of providing functional illumination.

indicator-type LEDs

Inexpensive, low-power LEDs suitable for use as indicator lights in panel displays and electronic devices or instrument illumination in cars and computers.

InGaN

The indium gallium nitride material system for manufacturing green, blue and cyan high-brightness LEDs.

junction

The p-n junction in a diode, where positively charged and negatively charged materials exchange electrons, emitting photons and generating heat. This is where the light in a LED is produced & emitted from.

junction temperature

The temperature in the vicinity of an LED’s p-n junction. Controlling junction temperatures is critical for achieving the optimal balance between lumen output and lumen maintenance. This is done with the use of a heatsink

lamp

The light source in a luminaire or lighting fixture.

LED

See light-emitting diode.

LED driver

An electronic circuit that converts input power into a current source-a source in which current remains constant despite fluctuations in voltage. An LED driver protects LEDs from normal voltage fluctuations, overvoltages, and voltage spikes.

light emitting diode (LED)

A semiconductor device that emits visible light of a certain color.

light level

See delivered light

light output

See luminous flux

lumen

The unit of measurement of luminous flux, the total energy that a light source emits across the visible wavelengths of light.

lumen maintenance

Describes how long a light source will retain a certain percentage of its initial lumen output. For instance, L50 is the length of time a light source retains 50% or more of its initial lumen output. A LED's output will get dimmer over time as it reaches the end of its life instead of a instant blow like traditional lamp types.

lumen output

The total lumens emitted by a lamp or luminaire.

luminous efficiency

The percentage of total lamp lumens that a conventional lighting fixture emits, minus any blocked or wasted light. By definition, LED lighting fixtures in which the LEDs are inseparable components have a luminous efficiency of 100%.

luminous flux

The total energy emitted by a light source across the visible wavelengths of light, measured in lumens.

lux (lx)

A unit of illuminance that measures the intensity of light falling on a surface area measured in square meters.

material system

The material, such as aluminum indium gallium phosphide (AllnGaP) and indium gallium nitride (InGaN), used within an LED to produce light of a specific color.

nanometer (nm)

The most common unit to describe the wavelength of light, equal to one billionth of a meter.

n-type material

In a diode’s p-n semiconductor junction, n-type material is negatively charged. Atoms in the n-type material have extra electrons.

phosphor

A coating of phosphorescent material that absorbs light from a blue or UV LED and emits most of its output in the yellow range. The proper combination of a blue or UV LED and a phosphor coating generates white light.

phosphor white

A method of producing white light in a single LED by combining a short-wavelength LED, such as a blue or UV and a yellow phosphor coating.

photon

The basic unit of electromagnetic radiation, including visible white light.

p-n junction

The location within an LED where negatively charged (n-type) material “donates” extra electrons to positively charged (p-type) material, which “accepts” them, releasing energy in the form of photons.

p-type material

In a diode’s p-n semiconductor junction, p-type material is positively charged. Atoms in the p-type material have electron holes-electrons missing from their outer rings.

pulse width modulation (PWM)

A method, used by most LED drivers, to regulate the amount of power to the LEDs. PWM turns LEDs on and off at high frequency, reducing total ON time to achieve a desired dimming level.

radiant flux

The total energy emitted by a light source across all wavelengths, measured in watts.

remote phosphor

A technique that separates the phosphor from the chip in a white-light LED, improving the extraction efficiency of emitted light.

RGB color model

An additive color model in which red, green and blue light are added together in different proportions to produce a broad range of colors, including white.

RGB white

A method of producing white light by combining the output from red, green and blue LEDs.

trailing-edge dimmer

A type of dimmer that regulates power to lamps by delaying the end of each half-cycle of AC power. Compatible with many LED fixtures.

tunable white light

White-light LED fixtures that combine channels of warm white and cool white LEDs to produce a range of color temperatures.

useful life

Refers to the lumen maintenance projections of the LED sources integrated into that fixture – the number of hours an LED lighting fixture will deliver a sufficient amount of light in a given application.

ultraviolet (UV)

Electromagnetic radiation with wavelength shorter than that of visible light.

watt (W)

the unit of power required to drive a LED lighting system.

Q: Is LED dimmable?
A: Yes. All LED is dimmable but the inbuilt driver circuits must also be dimmable. We sell both dimmable & non-dimmable lamp models which are listed as such. We also list compatible dimmer types. Occasionally a listed compatible dimmer will flicker at a certain point on the dial. There's a complex but logical reason for this & we'll spare you the lengthy explaination. We suggest if you experience this problem to switch to another compatible dimmer type or just avoid that point on the dimming dial. Back to top

Q: What is luminous flux?
A: This can be thought of as a measure of the total amount of visible light emitted & the unit of measurement is the lumen. For reference a 100 Watt incandescent bulb emits about 1200 lumens. Back to top

Q: Can I replace my lights with LEDs?
A: Yes & it's easy. Try to match 1) lampholder, 2) working voltage, 3) light colour & 4) beam angle. LED lamps come in a variety of lamp bases such as standard Bayonet cap(B22) and Edison screw(E27). Downlight lamps are available in E27, B22 as well as GU10, MR16 & MR11 bases. Please refer to our page on Lampholders Types. Our available voltages are 110V AC (USA), 220V-240V AC (the rest of the world), or 12V/24V DC. Colour selection is answered in the next question below. Match beam angle via lens selection. 60° is most common & this is what we recommend if you're unsure. If you have a dimmable lamp you may have to replace the dimmer with one that we have listed as compatible, this can be foung in the product description.  Back to top

Q: Cool white, warm white or daylight?
A: Warm white is best suited for relaxing. Its light creates a comfortable atmosphere suited for living rooms, bedrooms, restaurants etc. The luminous output of warm white LED is always a bit less than its cool white equivalent. Cool white has more blueish tones & compliments modern looking rooms with hard surfaces & stainless or chrome finishes ie bathrooms & kitchens. It is also a much better light for working. Daylight however is the best light for office/workspaces. Its light appears white more like daylight on a cloudy day. For more information view our colour guide page. Back to top

Q: Can temperature affect LEDs?
A: Yes! LED fixtures must be designed with junction temperature thermal management as a key component. We will not honour warranty claims if LED is installed in operating environments exceeding 50°c ie direct sun (external floods exempt) or extreme roofspaces. Unlike fluorescent sources, cold temperatures do not impact the performance of LED's & infact improve it. We have seen some real shockers in years past in which manufacturers and resellers boast high light output and lifespan but when put into a ceiling degrade quicker than you can imagine. All our LED is engineered & tested to the highest standards which you can view at our LEDshopper on Facebook page. Back to top

Q: Can I reuse my existing 12V or 24V AC transformers to power my new LED?
A: If it is wire wound it will work & even dimm with certain 240V dimmers but it is not advised & will void warranty claims. It is recommended that you replace AC supplies with a regulated DC power supply. This will ensure against overvoltage which can burn out your LED instantly even if it's only a few volts over. Wire wound transformers are also highly inneficient with losses at about 10% of output. For 240V LED the driver circuits can handle small voltage surges(±10%)but If large surges are a concern please install a surge diverter on the lighting circuit. Back to top

Q: Isnt voltage drop more of a problem with DC circuits?
A: Yes, but because LED's are so much more efficient with much higher luminous outputs the power consumed is far less. This means required  cable sizes are smaller also. 1.5mm cable is sufficient to power a 12V 200W load over 20mtrs. We suggest that 24V DC is the preferred working voltage as it is less susceptable to voltage drop than 12V DC. Please use 24V DC or a larger cable size if voltage drop is a concern. Remember twice the voltage means half the current. Back to top

Q: My LED's aren't as bright as they used to be?
A: LED's will lose their luminous intensity as they reach the end of their life. This occurs over a long period of time, about the last 5000hrs of a +50000hr life. This can be a positive as it will give you time to prepare for a relamp. We suggest at this stage you relamp all your LED at once as this is the most cost efficient method. Back to top

Q: What is RGB LED?
A: RGB is short for Red/Green/Blue & any colour in the visible spectrum can be achieved by mixing these 3 colours. If all 3 colours are mixed evenly we get white light. RGB LED is mostly used for decorative rather than practical lighting. RGB also requires a controller to mix colour levels & vary time increments. Some RGB LED have the controller inbuilt but unfortunately these inbuilt controllers with their preprogrammed scenes can be very mundane. To do it properly you need an external controller with the ability to write your own scenes. Back to top

Q: Are 50000hr lifespan claims true?
A: Yes & longer even, but lifespan can vary significantly depending on many factors. Mostly its how hard the LED is driven & the installation environment. The lifespan figure is obtained from accelerated ageing techniques & is only a estimation as it would take many years to do it otherwise. Regardless you can expect LED to far outlive every other lighting type available. Back to top

Bayonet cap & edison screw are the most common types that will be encountered and are represented as "B" & "E" respectively, followed by a number which represents the diameter of the lamp base. The standard bayonet cap is B22 which is 22mm in diameter with B14 being a mini-bayonet. The standard Edison screw is E27 in Australia but in America it is E26. 

All lampholder types work of the mains voltage in their respective countries & most LED lamps can tolerate a voltage range so will be compatible in any country. MR16 & MR11 are the exception which operate on a low voltage. 12V or 24V is most common for these lampholder types. Our MR16 & MR11 LED only operate on these voltages but with many manufacturers LED it can be almost any voltage. 

The image below shows the most common lamp bases. We have kept them to scale.

The beam angle you require for your LED light can be determined by what height your ceiling is from the object or floor space to be illuminated, and what lux level (brightness) is required in that particular area.

Selecting the right beam angle is important for both the look & feel of the room, & also the practicality of the working light. Usually, the widest lens available is 60° & this is most commonly used for general purpose lighting. If you are looking to highlight a particular feature or object, i.e. a statue or a kitchen bench, then a more focused beam may be necessary. Wide beam angles & high ceilings can leave low overall levels of light. This is especially true if the light is being absorbed by the surrounding walls & not getting to where it is needed. The opposite is also true, as with narrow beam angles & low ceilings you will get a very uneven light, which will also produce a hot spotting effect on the floor.

If you want to check the consistency of the light, a good trick is to walk around it with a sheet of A4 paper at waist level & observe the light on the paper. If you want to know if theres enough light to work with, then use a sheet with writing on it & try to read it as you walk. If you're retrofitting, a good method of selecting your LED would be to look at the existing lighting & then decide what you like & what you'd change.

Unless you've got very high ceilings, a 60° lens is the safe bet. If you're trying to focus light over a bench with a standard 3 metre high ceiling, then 45° is probably best. If you want to spotlight a statue or similar, then try 30°. Only in a very rare circumstances should you select a 15° beam.

Note: The wider the beam, the quicker the light will lose its intensity. As there is only a fixed amount of lumens emitted from each lamp, energy is wasted if the light strays outside of the area to be illuminated. 

There are also a lot of great links to associated LED articles to explore.