Q. How do they generate light?
Q. How do they change colour?
Most LEDs are monochromatic ie they emit light at 1 frequency, the different semiconductors used to create LEDs emit light at a variety of wavelengths from 400 nanometers (Blue) through to 800 nanometers (Red) a combination of Red Green & Blue (RGB) can then be used to create multitude of colours.
Stands for Red Green Blue & Amber.
Q. Are LEDs affected by extreme conditions?
LEDs are geared for harsh environments. LEDs function from -40F /-40C to 180F / 82.2C. There is no delay or required “warm up time” for LEDs to function.
Q. Can LEDs be dimmed?
Yes. In fact, LEDs love to be dimmed and unlike conventional lighting it actually extends the life of the LEDs.
Q. Do LEDs attract insects?
No they do not. Insects see entirely different spectrums of light and are attracted to ultraviolet light. A side note – flowers create “nectar guides”, invisible to the human eye and ultraviolet light attracts insects to flowers for reproductive purposes. This is not to say that all bugs aren’t attracted to LED lights, but most can’t see the light that LEDs produce.
Q. Can LEDs be damaged if hooked up backwards?
Yes, they can. LEDs are diodes and only allow power to pass in one direction. To ensure that you will get the most life out of our LED devices, we add additional circuits to prevent this from occurring in both AC and DC applications.
Q. Why do I need a Power Supply Unit?
Nearly all LEDs operate from low voltages (most njo products operate at 24VDC) and require a Power Supply Unit (“PSU”) to reduce the mains voltage supply down to the voltage or current that is required by the LED product. The PSUs are either constant voltage or constant current and range in output from 6W (for individual LED lights) right through to 1000W (for large schemes).
Q. What is Wattage?
Wattage is simply Current (in Amps) multiplied by Voltage and determines how much power is either available or will be consumed.
Example of a power (Wattage) calculation: 12 Volts DC x 3 Amps = 36 Watts.
Q. What is SELV?
Separated Extra-Low Voltage is intrinsically safe low voltage electric circuit. The low voltage is insulated from the mains supply voltages. SELV lighting products are ideal for use in areas where mains voltages could potentially cause harm or electrical shock such as bathrooms, water features and fountains.
Q. What is PFC?
Power Factor Correction is associated with Power Supply Units that have a mains input and a low voltage output. Power Factor Correction is given as a maximum figure of 1.0. For instance, a good quality Power Supply Unit will have a PFC figure of 0.98. A lower quality Power Supply Unit will have a PFC figure of 0.85 or less. The nearer to 1 this figure is, the smoother the Power Supply’s input current pull is. This drastically reduces the amount of energy required to produce the low voltage and current output.
Good PFC calculation:
230VAC mains voltage x 5 Amps x 0.98 PFC x 85% PSU efficiency = 958 Watts available output.
Bad PFC calculation:
230VAC main voltage x 5 Amps x 0.85 PFC x 85% PSU efficiency = 830 Watts available output.
Q. What is CCT?
Correlated Colour Temperature is a “colour swatch” of White light, comparing the colour of the light to radiation of light from a heated black body, and is measured in degrees Kelvin.
Warm White light has a colour temperature between 2,400K & 3,500K and could be compared to morning or evening sunlight. Mid White light has a colour temperature between 3,500K & 5,000K and could be compared to mid morning or mid evening sunlight. Cool White light has a colour temperature between 5,000K and 10,000K could be compared with mid day sunlight. Increasingly, LEDs are available in “tighter bins” – this means more specific Colour Temperature White LEDs can be built in our products.
Q. What is CRI?
Colour Rendition Index pertains to the quality of White light. CRI is given as a figure of 100. Good quality White light will have a CRI of 85 or above and will produce a clean White light. Low CRI LEDs will produce White light that will have a Reddish, Greenish, or Bluish hue. Low CRI lighting affects our perception of the objects we are viewing. Skin colours, vegetables, meats etc often appear unattractive in poor CRI environments. Good CRI lighting is critical in retail and display lighting.
Q. What is the difference between an incandescent bulb and an LED?
Incandescent creates light by the use of a filament. When power is applied, the filament glows and generates heat – which in turn produces light. LEDs are just the opposite. LEDs create light through a ‘cold process’. When power is applied to semiconductors (usually indium, gallium, arsenic and phosphorous), they’re stimulated by the movement of electrons, this creating photons. Photons are the light that is visibly seen by humans.
Q. What is Voltage Drop?
Voltage Drop is the loss of voltage along a length of cable due to the electrical resistance of the copper conductors inside the cable. The longer the cable and/or the higher the current, the greater the amount of voltage lost. Increasing the cable Cross Sectional Area (CSA) will mitigate against the loss of voltage. Voltage drops can be pre-determined using a simple calculation.
Q. How is Voltage Drop calculated?
Voltage Drop is calculated by multiplying the cable length (in metres) by the amount of current (in Amps) the cable has to carry by the expected Voltage Drop per Amp per metre of the cable.
The table below gives the expected Voltage Drop per Amp per metre of a range of standard 2 core lighting flexes:
|Cable Cross Sectional Area||Current Capacity||Voltage Drop (per Amp/metre)|
|0.5mm²||3 Amps||0.093 Volts|
|0.75mm²||6 Amps||0.062 Volts|
|1.0mm²||11 Amps||0.044 Volts|
|1.5mm²||15 Amps||0.029 Volts|
|2.5mm²||22 Amps||0.018 Volts|
|4.0mm²||28 Amps||0.011 Volts|
|6.0mm²||34 Amps||0.008 Volts|
To calculate the Voltage Drop in a cable, use the equation below:
Voltage Drop (per Amp/metre) x Current (Amps) x Distance (metres) = Voltage Dropped. E.g.
Cable Cross Sectional Area: 1.0mm² CSA
Voltage Drop per Amp/metre: 0.044V
Transferring these figures into the equation:
0.044 x 3.5 x 15 = 2.31 volts lost.
Generally speaking, we recommend that a suitable cable is chosen so that the resultant Voltage Drop is less than 2.0VDC.
Q. What is an “IP” Rating?
EN 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (i.e. tools, dust, fingers) and moisture. This classification system utilizes the letters “IP” (“Ingress Protection”) followed by two or three digits. (A third digit is sometimes used. An “x” is used for one of the digits if there is only one class of protection; i.e. IPX4 which addresses moisture resistance only.)
Degrees of Protection – First Digit
The first digit of the IP code indicates the degree that persons are protected against contact with moving parts (other than smooth rotating shafts, etc.) and the degree that equipment is protected against solid foreign bodies intruding into an enclosure.
Degrees of Protection – Second Digit
The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.)
Find out more on IP rating