Some downlights designed for outdoor use have transformers inbuilt because there is a greater chance of damage.
Downlights are handy to illuminate areas that are below head height. Some use halogen bulbs, some have fluorescent tubes and some LED bulbs. A transformer is a device that is used to change voltages. It can be used to:
Produce higher voltages from lower voltages.
Convert AC (Alternating Current) to DC (Direct Current).
Convert one AC frequency (usually 50Hz or 60Hz) to another.
A fluorescent tube requires a high voltage in order to start and the transformer must supply this initial or 'strike' voltage.
With LED bulbs, there is no strike voltage. They offer greater flexibility compared to other light fittings.Downlights come in a variety of shapes and sizes. All of them have some type of light source that is covered by either a protective coating or the translucent plastic dome that has been fitted over the light to diffuse it. The only downlight that needs a transformer is one with a fluorescent tube. The reason for this is the operating wattage of typical fluorescent lamps. This high starting voltage requires an electrical device called a 'ballast' to provide the necessary kick, as compare to the low voltage needed in the other LEDs. Some have built-in transformers for outdoor use or just as a precaution against damage through rain or vandalism etc. Fluorescent lights require transformers while LEDs do not due to low voltage. MR16 halogen downlights need one transformer for every globe. Most transformers in downlights are meant to connect to one halogen lamp with 35W or 50W. The halogen downlights can be either an electronic driver or a magnetic transformer. Many homeowners using MR16 halogen lights require several halogen transformers installed in the ceiling. Halogen transformers provide the light bulbs the needed If the old transformer has transformer issues, it can be replaced by a new transformer through an upgrade.
The main reason why a single transformer is used by manufacturers for lighting is to ensure that the fluorescent tube starts immediately when power is applied. Fluorescent tubes need this initial strike voltage in order to start lighting. LEDs do not.
If you have existing light fittings or aim to install LED downlights instead of fluorescent tubes then no transformer will be required during lighting since LEDs run on such little power supply, which saves on energy bills for many homeowners. The Australian Government has some great advice on lighting solutions on the energy.gov.au wesbite.The only time you would find a noticeable difference is when the switch is turned off and on again or after an extended period of time where LED lights have had their own internal capacitors discharge slowly.
One other thing to bear in mind is that turning the switch of an LED bulb on and off repeatedly can burn out the LED bulb or shorten its lifespan. The average life of an LED bulb is 20,000 hours – they consume such little power when ambient light levels are sufficient.
Dimmable LED downlights allows the adjustment of brightness to suit the mood of your house. The dimmable downlights are suitable for when you need to run LED lamps on low energy consumption, which leads to increased efficiency through lower light output.
Given the benefits of installing LED downlights, it is advisable to replace any existing halogen light fixtures for minimum wattage. LED downlights require no transformer while the halogen one requires a halogen transformer, along ceiling insulation. Current transformers incur a extra cost and effort, which implies an added advantage that you do not need a transformer with an LED since it has a driver built into its system. LEDs also have a dimming capacity made possible due their unique lighting technologies.An LED driver is a device that enables LED downlights to be dimmed. It does not change the voltage and therefore does not use a transformer. Some LED drivers also come with filters and optoisolators (devices that allow communication between circuits while preventing unwanted electrical noise) which help reduce interference. LED drivers can be powered by either AC or DC voltages and are made for indoor and outdoor use. The LED drivers are designed to control a single circuit (e.g. one chain of lights) using multiple LED downlights so you may need more than one LED driver if you wish to control several circuits in parallel. A LED transformer is used to step down the voltage from 230V mains power to 12V, 24V or 120V (for fluorescent tubes). LED transformers only have two hard wires – an input hard wire and output hard wire(s). If you want more than one circuit on a LED transformer then it requires a device called a multi-tap which enables multiple outputs from a single LED transformer. Multi-taps come in single-ended or double-ended versions.
Electrical safety should always be your first priority if you choose to install or replace the bulbs yourself. For example, installing the bulb is generally simple and takes less than 30 minutes but there are still risks involved in changing any electrical fittings let alone installing new ones.
For example, lighting problems can often arise when trying to work out what wires go where, or the right place to plug in the wires, so ask an expert if you have any doubts. A good electrician will test for power supply before touching anything, use the correct tools (e.g. wire strippers) and always wear rubber gloves and closed-in shoes or boots while doing electrical work for safety and efficiency.
Once the installation is done, test the efficiency by turning on the switch. Some people use a plug to connect the LED lights to a source of energy. Some challenges arising from poor wiring or poor circuitry include dimming and flickering lights. This could be caused by a higher voltage or much less power in the halogen lamps, or in LED lamps that do not have an LED driver. This can be controlled by ensuring the power supply is compatible with the LED lamp or halogen lamp.