User:Nathalie NL/Underwater Lighting

Underwater Lighting is a type of Lighting specially designed for use underwater. This lighting must meet the degree of protection IPX8 which means that the underwater light is dust and water resistant according to IEC 60529. Underwater lighting operates on low voltage, 30Vdc max according to standard IEC60364-7-702.

Halogen vs. LED
As with other types of lighting, for underwater illumination different light sources are used. Traditionally, underwater lights are equipped with halogen lamps. For several years, led underwater lighting is emerging in the market. The advantage of led is that this light source (under the condition of correct application) has a much longer lifespan than halogen. By comparison, a halogen underwater light has up to 1,500 burning hours, while a LED underwater lamp can reach 50,000 burning hours

Energy comsumption
The switch from halogen to LED has a significant effect on the energy consumption of underwater luminaires. There are now LED underwater lights on the market with a power consumption of 45W with significantly higher light output than a 300W halogen underwater light.

Fixture design
Many manufacturers have, in switching to LED, built upon the existing design of the halogen underwater light fixture which must be opened in order to replace the light source. For halogen lighting this is approximately 2 times per year (depending on intensity of use). As the lifetime of LEDs in theory is 20 to 50 times longer than halogen, some manufacturers have responded to this with a new design in which the light source is sealed-off water and airtight with special resin. This new generation of LED underwater lights have fewer problems with waterproofing.

Light Output
The unit of Luminous flux is measured in Lumen. For a good comparison between different underwater lights, it is recommended to compare the luminous flux in lumens of underwater luminaires.

Candela vs. Lumen
As with other types of lighting, the arrival of led has arisen many questions about the light output of lamps. Much of the confusion about light intensity is caused by the mix-up between Candela and Lumen. Manufacturers are not always clear in providing information about light output of an underwater lamp. The most powerful high-power LEDs for underwater use (2011) can produce up to max. 120 lumens per watt. A quick calculation then indicates that a 60W LED underwater lamp in optimal conditions (depending on driver, power and cooling) has a maximum luminous flux of 7,200 lumens.

Relationship Candela and Lumen
The calculator on this website can calculate luminous flux based Candela and the beam angle: http://led.linear1.org/lumen.wiz. For example: a lamp that emits 590 cd in an angle of 40°, sends out about 223 lumens. In calculating Candela to Lumen also take into account the beam angle, meaning the width of the beam. There are underwater lights with a narrow beam (25-30 °) which reach further and underwater lights with a wide beam (120-140 °) which can illuminate a pool evenly without dark corners. For safety reasons, public swimming pools often choose the latter.

LED type
Also affecting light output is the type of LED used in an underwater fixture. Here are three distinct types: An underwater luminaire with low power LEDs can be identified by the large number of LEDs in the Luminaire, sometimes 50 to 100 per fixture. The low power does not allow high light output. Only luminaires with Power LEDs and High Power Chip LEDs have the capacity of reaching light outputs similar to 150W halogen underwater lights and higher. In this type of LED lights, sufficient cooling of the fixtures is necessary due the LEDs generating heat, which does not occur with low power LEDs.
 * LEDs with a low wattage (0.5W - 1W per LED)
 * Power LEDs with a higher power (3W per LED)
 * High-Power Chip LEDs (15-35W per LED)

Technology
Also in terms of technology there are some differences between various underwater luminaires:

Heat generation and cooling
Underwater lamps with high light output have a certain heat generation. Sufficient cooling of the light source is essential for the life of this lamp. A light source that is too hot will have a much shorter life than a light source which is well cooled. For cooling the water in which the lamp operates can be used. An underwater lamp which is cooled by water should not be used above water, the light source will be damaged due to overheating. There are manufacturers who have lamps fitted with an overheating protection like the TCS (Temperature Control System) by EVA Optic. This automatically switches the lamp in a thermal protection when the LEDs have reached a certain temperature. Once the LEDs are cooled sufficiently, the lamp switches back on automatically.

Electronics
The quality of an underwater lamp depends on many elements, an important part of this being the electronics. A good underwater lamp uses a constant current driver for controlling the light. This affects the performance of the lamp, lamp life and energy .. consumption and reactive power of the lamp. In the majority of the underwater lights, the electronics are under water inside the fixture. There are also underwater lights with separate driver and power supply which can be placed above water in an area where moisture and heat have no effect. Some LED underwater lights are also dimmable.

Electrolysis
Underwater lighting is available in (high-quality) plastic and stainless steel. With underwater lights of high-quality plastic, the risk of electrolysis is less in comparison to stainless steel. Electrolysis causes a minor current between the pool wall and the stainless steel of the lamp. This current causes corrosion of the stainless steel.

Light color
Light consists of a spectrum of colors in different wavelengths, shown in Newton meters (Nm). The wavelengths that are visible to the human eye are approximately between 380 and 800 Nm (from low to high: blue-green-yellow-orange-red). Water absorbs light in a completely different way than air. This is because the density of water is about 800 times greater than air. This high density ensures that light is absorbed much faster. This absorption of light occurs in one color sooner than other colors. The light color with the highest wavelength in Nm, Red, is underwater almost completely absorbed. This absorption occurs less and less the lower the wavelength in Nm. Therefore, blue light under water has the highest light transmission, outside white which contains all colors in the spectrum.

RGB color and underwater lighting
Underwater lighting is available in several tones of white, mostly bright or daylight white and warm white. There are also underwater lights with a single color or RGB color changing lights. In colored LED lights there are two types of lamps available. The first type uses colored LEDs. These LEDs include only a small part of the full color spectrum and therefore cannot produce white light. The color contrasts are greater, but there are differences in light intensity (red has a much lower light intensity than blue). There are also underwater lights using white LEDs with color filters. The colors are less intense but the light intensity is the same with each color. The colors of surroundings and swimmers also remain the same, this is for public swimming pools often a requirement due to safety regulations.

Color of pool surface
Not only the water itself is responsible for absorption of light from the underwater lamp. The color of the surface of a pool or pond affects the amount of light a fixture yields in a pool. As a general rule, the darker the walls, the less light gets through and the more lights should be used to obtain equal lighting effects.

Applications
Underwater lighting or waterproof lighting for is used for many applications including; public swimming pools, water parks like Center Parcs, private pools, saunas, Jacuzzis and whirlpools, paddling pools, water slides, fountains, docks, ships and yachts, etc. Some underwater lights are only suitable for freshwater, chlorinated water or salt water. Other underwater lights can be used in any type of water. With the introduction of LED and changing the design and materials of underwater lighting, there are underwater fixtures able to withstand a pressure of 20 bar and can therefore be used in diving operations and diving pools.

Requirements pool light
In public pools certain requirements must be met. Underwater lighting is not required, so there are no regulations/requirements for light output. Yet in most public pools underwater lighting is used. Underwater lighting gives life guards a better have a better view of the swimmers. Public pools usually prefer using underwater lights with wide beams that provide even illumination for safety reasons.

Major international suppliers

 * Astral
 * EVA Optic
 * Hayward
 * Pentair