What should you know before buying LED Bulbs (Part:1)

Introduction:

• The market of LED Lights is blooming very fast. Many companies serve LED Bulb to their customer and it is not easy for customer to choose best LED Bulb among them.
• The customer does not aware the technical parameter of LED, so It becomes more difficult to find out the best quality of LED Bulbs.
• With traditional incandescent light bulbs it was simple to get the right light bulb.  If a 60 watt bulb is the broke or fused you have just get another 60 watt. When it comes to LED lighting, it’s very different.  Since LED light bulbs doesn’t use the same amount of power that incandescent bulbs use.
• LED is described in terms of incandescent equivalence so we may see an LED bulb described as a 60 watt equivalent when in reality it only uses about 9.5 watts. This is because LEDs are measured by lumens (the total amount of visible light put out by a light bulb).  There is not a direct mathematical comparison between the lumen ratings used in LEDs and the wattage consumed by an incandescent.
• To choose best LED Bulbs we should consider following technical Parameters.

Parameters for Choosing LED Bulbs

 There are different factors to consider when choosing a suitable LED replacement bulb

Basic Technical Parameters:

• Lumen (Lighting Intensity)
• Watt (Power Consumption)
• Correlated Color Temperature (Light color)
• Color Rendering Index (CRI)
• Beam angle (Spread of light)
• Efficiency (Lumen / Watt)
• Power Factor

Other Parameters:

• Instant Light
• Dimming capacity
• LED Driver
• LED Chip
• Weight
• Heating

 Basic Technical Parameter:

(1)  Lumen (Brightness):

• When we deal with brightness of LED bulb, we must to know Lumens not Watts.
• The amount of light emitted from a light bulb is measured in Lumens.
• When we replace an incandescent or CFL bulb with an LED bulb we should confirm that LED bulb produces the same number of lumens that the old bulb did.
• As a general benchmark, a standard 60-watt incandescent bulb, for example, produces about 800 lumens of light. By comparison, a CFL bulb produces that same 800 lumens using less than 15 watts
• Do not use watts as a measure of brightness.
• Lumens represent the amount of light emitted by a light source, and are a more accurate measure of the brightness of a bulb.
• More lumens mean brighter light, fewer lumens mean dimmer light
• 1 Foot Candle: 1 foot candle of light is the amount of light (Lumen) that generates one foot radius away from Lighting source so 1 Foot Candle= 1 Lumen / Sq.Foot
• 1 Lux: 1 Lux of light is the amount of light (Lumen) that generates one Metert radius away from Lighting source so 1 Lux= 1 Lumen / Sq.Meter

• It is meaningless if we compare lumens between an LED bulb and a CFL to an incandescent bulb. While we are measuring lumens, we also have to consider useful lumens.
• LED gives directional light unlike incandescent, halogen or compact fluorescent bulbs that give out omni-directional light (or light all around the bulb).  If a light bulb emits light in every direction similarly over and beneath, then light that going up can get trapped in the light fitting and totally wasted.
• 50% of light emitted from a CFL or incandescent bulb is trapped inside the fitting and never makes it out and reached to objects. This trapped light is just gets absorbed and wasted as heat.
• The amount of lumens that actually reached at the objects of Room that bulb produces are called as the useful lumens.

• There is no rule for how many Lumen is required.It will depend on room size and shape, height of ceilings, colour scheme, type of lamps & fitting.

 (2)  Watt (Power Consumption):

• The amount of energy a light bulb consumed is indicated by Watt.
• The watts refer to how much energy a bulb will use.
• The lower the watts, the lower the electric bill. CFLs and LEDs have a lower wattage than incandescent bulbs, but emit the same light output
• Watts measure power consumption, whereas lumens measure light actual brightness..
• Wattage is no longer a reliable way to gauge a light bulb’s brightness.
• In old days, when there was only one basic type of incandescent light bulb was available.consumers could buy the incandescent bulb on the term “watts” .
• Incandescent lamps use the filament material heated to the same temperature, the only way to increase their light output is to increase the wattage. We actually feel difference in brightnes between 60 Watt, 100Watt or 150 Watt light bulbs incandescent bulb.
• When new technology introduce The energy-saving CFL bulbs of 15 Watt CFL bulb produced the same light of a 60 Watt incandescent. A 25 Watt CFL was comparable to a 100 Watt incandescent in light output.
• Generally LEDs produce the same amount of light as an incandescent bulb that has five to six times the wattage.
• LED sources are much more efficient at converting watts to lumens. Different materials can be used within the LED sources with different light extraction efficacy so two different LED sources can consume the same number of watts but having different  lumen output.