What is  LM79 LM80 L70 PF THD for LED Lighting ?

What is LM79 LM80 L70 PF THD for LED Lighting ?

24 FAQ  for LED Lighting about What is LM79 LM80 L70 PF, THD etc. 

Here we summerize all questions you might rise, and give all answer, an ultimate lighting training courses on:

1. What is Power Factor

2. What is Color Rendering Index

3. What is Color Temperature

4. What is Foot Candle

5. What is Total Harmonic Distortion

6. What is 0-10V dimming ?

7. What is lighting distribution patterns ?

8. What is mircrowave sensor,

9. What is HID LED retrofit

10. What is lumen efficacy

11. What is singled ended power and dual ended power

12. What is LM79 LM80 L70 ?

13. What is LED lifespan ?

14. How many kinds of socket base in market for LED lighting ?

15. What is IP rating ?

16. What is Type A, Type B, Type C and Type A+B t8 tube ?

17. What is amber light ?

18. What is ballast compatible t8 tube and ballast bypass tube ?

19. What is PWM ?

20. What is IR remote sensor control ?

21. What is Occupancy sensor control ?

22. What is AC and DC ?

23. What is difference between constant current and constant voltage ?

24. What is SMD and COB difference etc. 

25. What is photocell sensor ?

1. What is Power Factor ?

Power factor is used to describe the effiency of power supply of LED driver, the higher the rate is, the more efficient to transform the electricity into light.

That is to say, the driver itself consumes less power.

Usually, LED driver power factor is over 0.9, if you test a LED driver that has less than that, that is not defective in its design.

2. What is color rendering index (CRI) ?

Color rendering index is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source.

For indoor lighting, CRI should be over 80Ra, while some special occassion, it requires 90Ra. Regarding for outdoor lighting, CRI over 70Ra is great.

effect of CRI value difference

3. What is color temperature (CCT)?

Color temperature is to describe the light appearance provided by a light bulb (lamp).

It is measured in degrees of Kelvin (K) on a scale from 1,000 to 10,000. 2700K-3500K is warm white, 3500K-4500K is daylight/natural white, and over 5000K is refered as cool white.

If you need warm white atmosphere or if you are living cold area, you can take 2700K-3500K to feel a little warm.

If you need very bright atmosphere or if you are living hot area, you can take over 5000K.

Color temperature belt

4. What is FC( foot candle )?

Foot candle is a measurement of light intensity and is defined as the illuminance on a one-square foot(=lm/ft²) surface from a uniform source of light, also known as illumination intensity internationally(lm/m²) (unit: lux), 1fc = 10.76 lux. 

what is foot candle

5. What is total harmonic distortion(THD) ?

THD is a measurement of the harmonic distortion present in a signal and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency.

For LED lighting industry, THD should be less than 20% .  

Lower THD means pure signal emission without causing interferences to other electronic devices.

6. What is 0-10V, 1-10V dimmer ?

0-10V is an analog lighting control protocol. Basically, a 0-10V control applies a voltage between 0 and 10 volts DC to produce a varying intensity level. 

The controlled lighting should scale its output so that at 10V, the controlled light should be at 100% of its potential full output, and at 0V it is at the lowest dimming level.completely off.

While 1-10V dimmer, it cannot dim the light completely off, still 10% light output.

7. What is light distribution Type I, Type II, Type III, Type IV, Type V etc ?

type I lighting distribution

type III lighting distribution

type V lighting distribution

8. What is microwave sensor ?

Microwave sensors, also known as Radar, RF or Doppler sensors, detect walking, running or crawling human targets in an outdoor environment.

It generates an electromagnetic (RF) field between transmitter and receiver, creating an invisible volumetric detection zone.

When an intruder enters the detection zone, changes to the field are registered and an alarm occurs


9. What is HID LED retrofit ?

LED retrofit refer to any renovation of old HID bulb that has edison socket base E26(mdium) E39(mogul) base such as

Metal halide(known as MH),

High pressure sodium(known as HPS),

Mercury vapor (known as MV),

Into LED lighting bulbs with E26 E39 base in order to keep the old lighting fixture and save cost. 

10. What is lumen efficacy ?

Lumen efficacy is the amount of visible light per light source, it is messured by lm/watt.

The higher the number is, the better. That means, more electricity has transformed into light, less heat produce.

Therefore, we need to choose the lumens output over wattage option.

That is to say, if there is a 15W 120lm/w t8 tube and a 18W 100lm/w t8 tube, the same lumen output (lighting effect), but 15W can save more energy and less electricity bill. 


11. What is single ended power ? dual ended power (double ended power) ?

In single ended powered tubes, you power only one end.

This type of installation is referred to as un-shunted. Since the tube has two pins on that end, you would send line to one pin and neutral to the other. (think of line and neutral as the black and white wires of electrical wire)

In double ended powered tubes, you power both ends, one with line source, the other with neutral. This type of tubes’ installation is referred to as shunted.

difference of single ended power and dual ended power

12. What is LM79 LM80 L70 test report ?

what is LM 79 ?

LM79 is the Illuminating Engineers Society North America (IESNA) approved testing method to generate electrical and photometric measurements of solid state lighting (LED) products.

It is an electrical and photometric test of LED luminaires.

Measurements include: total flux (light output), electrical power (wattage), lumens per watt (efficacy), and chromaticity

What is LM80 ?

LM90 is the Illuminating Engineering Society of North America (IESNA) approved method for the Electrical and Photometric Measurements of Solid-State Lighting.

It measures an  integral lamp as a whole system according to a standard process using specified equipment.

In other word, it solely measures the lumen depreciation of the LED module

What is L70 ?

LM70 is the amount of time it takes for a light to degrade to 70% of initial lumen output.


13. How is the LED lamp or LED fixture lifespan 50,000hrs tested ?

The LED lifespan 50,000hrs is an estimate value based on the test TM-21, LM79 test report, not the genuine data.

It genuine lifespan depends on how long to use every day and how hot or cold your application, these factors affect a lot to the light lifespan. 

lifespan comparison between LED CFL incandescent Halogen

14. How many kinds of socket base there are for LED lighting ?

There are several Edison socket base in United States, E12(candelabra), E17 intermediate base, E26 medium base, E39 mogul base.

socket bases summary

15. What is IP rating ? IP20, IP40, IP44,  IP65 etc.

This is a rating system that defines the ability of a product to be able to work in different environments.

IP is an acronym “Ingress Protection”. It is a measurement of the protection an item will have against solid objects (dust, sand, dirt, etc.) and liquids.

An IP rating is comprised of 2 numbers. The first number refers to the protection against solid objects (dust, etc) and the second number refers to protection against liquids

IP65 = Water resistant. “Protected against water jets from any angle” *Do NOT submerge IP65 LED lights, these are not waterproof.

IP67 = Water resistant plus. “Protected against the events of temporary submersion (10 minutes)”*Do NOT submerge IP67 LED lights for extended periods, these are not waterproof.

IP68 = Waterproof “Protected against the events of permanent submersion up to 3 meters”

16. What is UL Type A+B, Type A, Type B, Type C  LED t8 tube ?

Type A + B (Internal driver): 2ft 3ft 4ft 8ft and U-bend LED “tubes” operate utilizing the existing fluorescent ballast and also have the ability to operate utilizing line voltage if the fixture is rewired to bypass the ballast.

These tubes connect to the fixture using standard G13 pin-base connections to the lampholders.  

Type A (internal driver):  2ft, 3ft, 4ft, 8ft and U-bend LED “tubes” employing lampholders to connect to the fixture being retrofitted and are designed to be “plug and play” replacements for 2ft 3ft 4ft 8ft T8 T12 fluorescent lamps.

It operate utilizing an existing fluorescent ballast, and do not require mechanical or electrical changes to the fixture. 

Type B(internal driver): 2ft 3ft 4ft 8ft and U-bend LED “tubes” employing lampholders to connect to the fixture being retrofitted, but do not operate utilizingthe existing fluorescent ballast.

These products require rewiring of the existing fixture to bypass the ballast and send line voltage directly to the lamp holders.

Type C(external driver): 2ft 3ft 4ft 8ft and U-bend LED “tubes” employing lamp holders to connect to the fixture being retrofitted.

Do not operate utilizing the existing fluorescent ballast, and require rewiring of the existing fixture to replace the ballast with an external driver.

The lamp holders are then wired to receive only the low-voltage electricity that is supplied by that external driver


17. What is amber light ? it is the same with warm white yellowish light ?

Amber light is yellow light, but it is pure yellow light, no other lightwave, not like the warm white light which contains several kinds of lightwave. 

18. What is ballast compatible t8 bulb mean ? what about ballast bypass t8 light bulbs ?

Ballast compatible t8 tube can be working directly with traditional ballast like magnetic ballast or electronic ballast.

It has the advantages as follow:

You don’t need to remove the ballast, just screw the T12 or T8 fluroescent out and screw in the ballast compatible t8 tube, no need rewiring, no hassle, plug and play tube, very convenient.

While for the ballast bypass t8 tube, on the other hand, cannot work together with the ballast when retrofit the T8 T12 fluorescent.

You need to remove ballast and starter, then direct wire to the LED tubes, in this way, it can work.

Some ballast bypass t8 tube light is single ended power, other is dual ended power or double ended power, their wiring diagram is different.

Therefore, invite qualified professional electrician to retrofit t8 tube safe. 

19. What is PWM dimmer ?

PWM stands for Pulse Width Modulation which is a specific way that LED lights are dimmed.

Basically this dimmer works by sending a pulse or flicker to the light at a rate that the eye cannot detect in order to achieve 256 levels of dim

20. What is IR remote control ?

An IR remote is short for Infrared, meaning it has to be pointed directly at the Infrared sensor on the controller in order for the remote to function.

21. What is occupancy sensor ?

It is an indoor motion detecting devices used to detect the presence of a person to automatically control lights or temperature or ventilation systems.

The sensors use infrared,ultrasonic, microwave, or other technology.

The term encompasses devices as different as PIR sensor, hotel room keycard locks and smart meters.

22. What is AC and DC ?

AC stands for alternative current, this is the electricity that is used in most homes and commercial spaces.

It’s often referred to as line voltage and number differs from country to country. US line voltage is typically 90V-220V

DC stands for direct current. Most LED strips on the market use low-voltage DC. A transformer or low-voltage battery is often required to step-down the AC voltage to a suitable level for the LED strips, which is normally 12V or 24V DC

23. What is constant current and constant voltage ?

A constant voltage power supply is an electrical power source that regulates voltage to a constant level.

In the case of  LED strip lights, a constant 12V or 24V, depending on the LED strip being used, would be required

24. What is SMD and COB ?

SMD is short for surface mounted diode, so much commonly seen in light bulb and strip light, typically producing 4-5lm per diode on a chip, and it is often an array of  LED on a PCB board.

Therefore, SMD beam angle is wider than COB, but a frosted reflector are required to hide the array. 

COB is short for chip on board, which contains multiple diodes in a single wafer or chip.

So COB chips watt can be made very high and require good thermal design to make efficient heat dessipation out of the wafer. 

SMD and COB difference

25. What is photocell sensor ?

Photocells are sensors that allow you to detect light, it is turning exterior lights on at sunset and off at dawn.

Because they sense ambient light levels, photocells automatically adjust to seasonal changes in the day/night cycle and are unaffected by daylight-saving time.

Photocells controlling exterior lights combined with timers that turn on interior fixtures create the illusion of occupancy when you’re not home, which can deter intruders.

Other photocell uses include turning on parking-lot or street lights after dark, adjusting indoor dimmers to compensate for changing natural light levels or switching illuminated business signs on or off

24. What are cut off, full cut off, semi cutoff ?