How to choose an LED lamp
Author: Alexey Nadyozhin
Unlike conventional incandescent bulbs, which differ only in power and workmanship, LED bulbs have many parameters that affect the quality and safety of lighting. I will talk about the main parameters of LED lamps and recommend which lamps are best suited for your home.
LED lamps should not be chosen according to power - the efficiency of different lamps is different and lamps with the same power can vary greatly in brightness: lamps that replace a conventional 60W pear bulb can have a power of 6 to 10 W, lamps that replace a 40 W “candle” may have power from 4 to 7 watts.
Most manufacturers of LED lamps indicate the equivalent of incandescent lamp power. For example, the package may indicate that the lamp has a power of 6 W and shines like an incandescent lamp 60 W. Some manufacturers indicate this equivalent is quite incorrect, so I recommend always paying attention not to the power equivalent, but to the luminous flux.
The brightness of the lamp, or more precisely the amount of light that the lamp gives, is determined by the “luminous flux” parameter, measured in lumens (lm, lm).
For ordinary lamps (pears, candles) you can estimate the necessary luminous flux by multiplying the power of an ordinary incandescent lamp by 10: 40 W - 400 lm, 60 W - 600 lm, 100 W - 1000 lm. Thus, if you want to buy an LED lamp to replace a 60-watt incandescent lamp, look for lamps with a luminous flux of at least 600 lm.
Unfortunately, many manufacturers overestimate the value of the luminous flux. In reality, it may even be twice as low as it was declared and the lamp, which should shine like a 60-watt incandescent lamp, will only shine like a 25-watt one. The real values of the luminous flux can be found only from the results of independent testing.
Glow Lama shine warm yellowish light with a color temperature of 2700-2800K. If you want the LED lamp to produce a light that is most similar to incandescent light, choose lamps with a color temperature of 2700-2800K. Many LED lamps have a color temperature of 3000K - this is more white, but no less comfortable light.Light bulbs with a color temperature of 4000K are called "neutral white." This light is more suitable for office premises. It is believed that white light contributes to increased efficiency, and yellow helps to relax and rest, so at home in the evening the light should be warm with a color temperature not higher than 3000K. Lamps with cold white light 5000K and above are designed for use in business premises. They do not belong at home.
The LED lamps working from a network of 220-230 V and from power supplies of 12 volts are issued.
LED lamps use drivers (electronic boards installed in the lamp base) of different types. Many lamps use drivers with stabilization. The brightness of such lamps does not change when the mains voltage fluctuates in very large limits. Some of the lamps shine equally brightly when the mains voltage drops from 230 to 70 volts. Unfortunately, manufacturers often do not indicate the actual voltage range: 220-240 V or 230 V can be written on the lamp packaging, but in reality the lamp burns at a much lower voltage.
12 volt lamps are available with E27, E14, GU5.3, G4 sockets and can operate from both direct and alternating voltage.Most of the microlamps with the G4 socket and some spot lamps with the GU5.3 cap when operating on AC voltage have a very high light pulsation, harmful to the eyes and overall health. In order to avoid the pulsation of such lamps, you will have to replace the transformers with DC power supplies.
Color rendering index (CRI, Ra)
LED light differs from incandescent light in its spectrum. Although the light and looks white, some color components in it more, and some less. The color rendering index shows how uniform the level of different color components in light. At low Ra, shades are less visible. Such a light is visually unpleasant, and it is very difficult to understand what is not in it. For incandescent and sun lamps Ra is higher than 98, for good LED lamps it is more than 80, for very good more than 90. Lamps with Ra below 80 in residential areas should be avoided.
Unfortunately, some manufacturers overestimate Ra: on the box they write Ra> 80, but in fact it only slightly exceeds 70 and it is better not to use such lamps in living quarters.
Operation with a switch having an indicator
Many LED lamps do not work properly with switches that have an indicator light or LED. When the switch is off, these lamps flash or faint.Only some manufacturers indicate whether their lamps operate with such switches.
Most LED lamps cannot work with dimmers (dimmers), but special dimmable LED lamps are available that support brightness control. Such lamps work with most conventional dimmers for incandescent lamps, but the minimum dimming level can be quite high (about 20%). In order for the dimming lamps to reduce the brightness to almost zero, it is necessary to use special dimmers for LED lamps.
The pulsation of light leads to eye fatigue and a general deterioration of health, therefore it is very important to use only those lamps that do not have a visible pulsation. According to the SNIP for various types of premises, the pulsation of light is normalized in the range of 5-20%, in fact, pulsation of up to 35% is imperceptible for a person. Only some manufacturers write on the packaging of lamps "without pulsation." Other lamps may have a low ripple level, but this is not indicated in the lamp parameters. The presence of a ripple can be checked using the “pencil test” or by looking at the light of the lamp through the camera of a smartphone (if there is a ripple, stripes will be visible on the screen).
Conventional incandescent lamps shine in all directions, halogen spots give a narrow beam of light. With LED lamps all the more difficult.
Many LED bulbs, replacing conventional incandescent bulbs, have a hemispherical cap of the same diameter as the housing. Such lamps practically do not shine back and if they are directed downwards, the ceiling will remain dark, which may not be comfortable. Fortunately, in recent times a lot of lamps, a transparent cap of which is larger than the body and due to this the lamp shines a little and back.
Filament lamps have the same high angle of illumination as ordinary incandescent bulbs.
Most LED spotlights (lamps for suspended ceilings with GU10 and GU5.3 bases) shine with diffused light at an angle of about 100 degrees and dazzle due to too wide an angle (halogen spots give a narrow beam of light with an illumination angle of about 30 degrees). Only a few LED spots have the same narrow angle of illumination as halogen lamps. Such lamps are easy to recognize by the presence of lenses in front of the LEDs.
In a conventional LED lamp, several LEDs are covered with a cap (usually frosted).Sometimes there are still outdated corn-lamps, the entire surface of which is covered with many small LEDs that resemble corn grains on the cob. New type of LED lamps - filament lamps (or lamps on LED threads). Such lamps look very similar to incandescent lamps - they have a glass bulb and a wide angle of illumination. Inside the lamp there are LED strings - ceramic or metal plates, on which there are many small LEDs in a row.
Such lamps are more efficient than ordinary (they give more than 100 Lm / W) and their light is most similar to incandescent light. Most of the filament lamps are transparent, but there are also matte ones. The disadvantage of such lamps - lower service life compared to conventional LED lamps.
Manufacturers indicate lamp life from 10,000 to 50,000 hours. In fact, no one knows how long the lamp will last in reality, because technologies are being improved very quickly and all service lives are calculated theoretically. I recommend that you pay attention not to the specified service life, but to the warranty period during which you can exchange a lamp that is out of order.
All LED lamps have a warranty from 1 to 5 years. Shops are required to change the lamps under warranty during this period if they fail. In addition, under the Consumer Protection Act, you can return the lamps to the store within 14 days after purchase, if you didn’t like them, provided there is intact packaging and, if possible, a receipt.
How to choose a good lamp
The choice of LED lamps is not an easy task. Even among the most famous manufacturers, there are lamps with unacceptably high ripple. For some manufacturers, some of the lamps are good, and some are not. In order to know exactly which lamps are good and which are not, I created a project for independent testing of LED lamps lamptest.ru. I test the lamps and publish the measurement results of all the basic parameters. More than 1000 models of 75 brands of lamps have already been tested and work is continuing. Therefore, the easiest choice is to find the lamptest you are interested in at lamptest and look at its measured parameters:
• pulsation coefficient should not exceed 35% (and it is better that it is less than 10%);
• color rendering index should be at least 80 (for business premises it is possible from 70);
• the luminous flux must be not less than that of the incandescent lamp, which you want to replace the LED;
• If you have a switch with an indicator installed, make sure that the lamp can work with it correctly.
• if you have a dimmer set, make sure the lamp is dimmable;
• If you choose spotlights, pay attention to the angle of illumination. Lamps with an angle of more than 50 ° will dazzle when installed in the ceiling of a large room.
If the lamp you are interested in is not yet on the site lamptest.ru, I recommend to be guided by the following selection criteria:
• if the package indicates “no pulsation” with a high probability that the light of the lamp will pulsate will be less than 5%. If this is not indicated and there is an opportunity to turn on the lamp, look at its light through the camera of a mobile phone. There should be no stripes on the screen. Try twisting a pencil or other long object in front of the lamp. If the contours of the pencil are blurred - there is no ripple, if you see "a few pencils" there is a visible ripple and you should not buy such a lamp.
• See how your skin looks like under the light of a lamp. If the color is grayish, the lamp has a low color rendering index and it is better not to buy it.
• Compare the brightness of the lamp light with the brightness of the incandescent lamp or another lamp whose brightness you know. An approximate comparison can be made using the light sensor of most Android smartphones. Install any luxmeter application (for example, Sensors Multitool and there choose "light"). The sensors of all smartphones are not calibrated, so the values of all smartphones will be completely different, but for comparison, it does not matter. In advance, take home a frosted lamp of the same shape as you want to buy, run the application and lean the smartphone with the sensor to the lamp (the sensor is above the screen on the left or right, bring it to the top of ordinary lamps and to the center of the side of the candle lamps). Record the resulting value. In the store, turn on the lamp, wait at least a minute (when warming up, the LED lamps lose up to 12% brightness), launch the application and lean the sensor against the lamp. Compare the value with the measured at home. Now you will almost certainly know if the lamp being measured is brighter than the one that was measured at home, or dimmer.
• Pay attention to the date of production of the lamp (most lamps it is indicated on the body). If the lamp is released more than two years ago, it is better not to buy it - progress is very fast and modern lamps are better than those that were produced before.
• Pay attention to the warranty period. If the warranty is large (3-5) years, the probability of lamp failure is much less.
• After purchase, take a photo of the receipt. If the lamp fails, this photo will help you change it under warranty, if the usual check is lost or faded.
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