Type of Light Bulb base & Socket:Part-1


  • A lamp holder is the device which holds a light bulb or lamp. It’s important that the lamp holder is compatible with the type of bulb we want to use, with the wrong base selection will not fit in the lamp or fixture.
  • Light bulb sockets are normally defined by a letter-number-letter (Third Letter is optional).
  • The first letter indicates the shape of the base.
  • The Second numbers indicates either the width of the base or the distance between the pins.
  • The Third Letter indicates the number of pins or contacts on the lamp. The numbers are normally in millimeters.

Type of Sockets:

There are different types of Socket available in market

  1. Bayonet Cap Base (B)
  2. Edison Screw Cap Base (E)
  3. Single Pin Type Base (F)
  4. Bi Pin or Multi Pin Type (G)
  5. Cable Connections (K)
  6. Pre- focused Light Base (P)
  7. Recessed Contact Base (R)
  8. Flange Base Light Bulb Base (F or T)
  9. Slide Base (S)
  10. Wedge Base (W)
  11. Special Type Light bulb Base (X)

(1)  Bayonet Cap (B / BC / SBC):


  • Type of Connection: “push and twist” action
  • Pin Configuration: (Bxx or BCxx):
  • The First letter indicates the shape or Style of the base.
  • The Second number indicates the width of the base (normally in millimeters).
  • Example:
  • The “B” refers to the style of Base which is a Bayonet, and the 22 means it has a 22 mm base width.
  • Application: All Regular type of Bulbs including specialist low voltage halogen lamps

(2) Edison Screw Cap (E / ES):

  • Named as inventor Thomas Edison, the Edison Screw or “ES” lamp fitting is used in a vast range of applications.


  • Type of Connection: “Screw” Action
  • Pin Configuration: (Exx or ESxx):
  • The First letter indicates the shape or Style of the base.
  • The Second number indicates the width of the base (normally in millimeters).
  • Example: E26 base.
  • The “E” refers to the style which is an Edison screw-in, and the 26 means it has a 26 mm base width.
  • Application: Large chandeliers Some Decorative Lamps.
  • The most commonly used screw fittings are shown in the table below. Other, less frequently used, sizes include E11, E17 and E26.
Designation Diameter Name Abbreviation
E5 5mm Lilliput Edison Screw LES
E10 10mm Miniature Edison Screw MES
E12 12mm Candelabra Edison Screw CES
E14 14mm Small Edison Screw SES
E17 17mm Intermediate Edison Screw Base IES
E27 27mm Medium Edison Screw ES
E39 39mm Mogul or Giant Edison Screw Base GES
E40 40mm Giant Edison Screw GES

(3) Bi Pin or Multiple Pin Type Base (G)


  • The “G” type of lamp base is used to as a “pinned” base. This may be several Numbers of different Types of pins.
  • Type of Connection: “Pin” Type
  • Pin Configuration: (G(U,X,Y,Z) -xx-x-x):
  • It is indicate by Letter (or Letters)-Numbers-Optional letter- Letter:
  • The first letters includes “G” which is followed by a Second (optional Letter) Letter U, X, Y or Z.
  • The second letter (U, X, Y,Z) represents the configuration of the base, which determines the diameter and shape of the pins. For example, pins may be rounded, square, grooved, fat or slender.
  • Without any Optional Letter = Base length is 8.25mm and Pin Diameter is 0.7mm
  • For Y=Base length is >6mm and Pin Diameter is 0.7mm
  • For X= Base length is <7.5mm and Pin Diameter is 1mm
  • For U= Base length is >6mm and Pin Diameter is 1mm With One or Two Grip channel.
  • For Z=P Base length is >6mm and Pin Diameter is 1mm without Grip Channel.
  • The Third number indicates the Distance in millimeters between the centers of each pin.
  • The Forth (optional Letter) Letter indicate the number of pins, no letter means 2 pins. d for double Pin ,s for Single pin, t for Triple pin or 3 pins and q for Quadruple pin or 4 pins.
  • The Fifth Letter indicates position of Dowel (Slot) in Socket
  • Examples: GU10 base type, GU24q 2Pin base type, G13d 3pin.
  • For GU24q 2 Socket, U=Pin length is>6mm with diameter 1mm with Grip channel, No of Pin is 4 no’s and Dowel is on Left Side
  • Application: Halogen, Compact Fluorescent ,LED Types Bulbs


Difference between G24q-1, G24q-2, G24q-3 Type Socket

  • Here G=Type/ Shape of Socket
  • 24=Distance between each Pin
  • q= Quadruple (Four) Pin.
  • 1=Indicate Dowel (Slot) Position ,1=Middle, 2=Left, 3=Right Position

Difference between Gx24, G24 Type Socket

  • In Gx24 The Base is smaller while in G24 Base is larger.


Type Pin to pin distance Pin Diameter Typical Bulbs that use this base
G4 4mm 0.65-0.75mm MR11 and other small halogens of 5/10/20 watt and 6/12 volt
GU4 4mm 0.95-1.05mm
GY4 4mm 0.65-0.75mm
GZ4 4mm 0.95-1.05mm
G5 5mm T4 and T5 fluorescent tubes
G5.3 GU5.3 GX5.3 GY5.3 5.33 mm 1.47-1.65mm MR16 and other small bulbs typically using 12/24 volts
G6.35 GX6.35 GY6.35 6.35 mm 0.95-1.3mm
G8 8mm
G9 9mm
GU10 10mm bulbs using twist-lock bi-pin base
G13 12.7mm T8,T10 & T12 fluorescent tubes
G23 23mm 2mm
GU24 24mm 2 and 4 pin bases with center key
GX53 53mm used with puck shaped lamps typically twist-lock

How to select MCB / MCCB (Part:3)

(E) Others:

 (1) Frequency:

  • MCB is designed and used in AC power system of 50 to 60Hz.
  • Electromagnetic force of magnetic release is related with power supply frequency so If Frequency is changed than electromagnetic fore of Magnetic element is changed hence MCCB tripping current will be different.
  • If we used MCCB for protection in DC circuits than specially design DC circuit MCCB should be used rather than normal type of MCCB.

(2) Isolation:

  • MCCB is suitability for visible isolation. It is particularly important.
  • If a circuit breaker is turned off, it should indicate so visibly.
  • It should not be able to indicate otherwise if the contacts are not open. In other words, it offers proof of isolation.

(3) Type of Mounting Arrangement:

  • According to mounting arrangement, MCBs can be divided into two categories.
  • DIN rail mount MCCB
  • Plug-in MCCB
  • DIN Rail Mount MCB
  • The main advantage of this type of MCB is versatility
  • DIN rails are used by many different types of electrical and communications equipment, and they are mainstream in industrial settings.
  • They can be easily integrated into nearly any control or protection system.
  • A disadvantage of this type of MCB is that more work is required for installation, and plug-in MCBs may be a better choice for simple installations.
  • Plug-In MCB
  • These MCBs are easy for installation. As name indicates, they just have to be plugged into a compatible electric panel.
  • Plug-in MCBs are suitable for applications that use circuit breakers exclusively- typically residential and commercial electrical distribution systems.
  • When using plug-in MCBs it is important that the breakers and the panel must match. It is not an issue when both are of the same brand

(4) Pollution degrees:

  • It determines in what kind of environment circuit breakers can be installed.
  • In a Domestic purpose where there is no dust no humidity, the circuit breaker is comfortable.
  • For Domestic purpose pollution degree 2 is suitable.
  • But in an outdoor public installation where there may be dust which cause leakage currents and lead to dangerous arcs.
  • For dusty pollution, humidity environment or outdoor type heavy-duty applications (incoming switchboards) pollution degree 3 is suitable.

(5) Energy Class:

  • MCB need some time for tripping, In this time, fault current will create some energy which will exist in system.
  • This energy is termed as release energy. For efficient MCB operation it should be in within limited. On basis of amount of release energy it is classified in class 1, class 2 and class 3.
  • Class 3 is best which allows maximum 1.5L joule/second.

 Example of MCB / MCCB specification / Name Plate:

Frame: F750
Rated Operational Voltage (Ue):        415V
Rated Insulation Voltage (Ui) : 690V
Rated Impulse withstand Voltage (Uimp): 6KV
Rated Current (Ie) : 80A
Ultimate Breaking Capacity (Icu): 10KA
Service Breaking Capacity (Ics) : 75 % of Icu
Utilization Category : A Type
No. of Poles:   3
Suitability for Isolation: Yes
Electrical Life Cycles : 5000
Mechanical Life Cycles:         25000
Release Type : Thermal – Magnetic
Thermal:          Fixed
Magnetic: Fixed
Terminal Capacity Cable: 50 mm2
Dimensions (mm) WXHXD : 75X130X60
Weight:            0.84Kg
Operating Temp Range:  -5 to +50°C
Reference Temperature: 50°C

 Main factors affected on cost of MCCB for same rating

  • Short circuit Capacity
  • No of Poles
  • Type of Application (Characteristic Type)
  • Type of Trip Mechanism (Thermal-Thermal-Magnetic, Solid, Microprocessor)
  • Accessories

 What should we select MCB or MCCB

The selection of MCB or MCCB depends upon your application. Main difference between MCB and MCCB is

Characteristics MCB MCCB
Standard IEC60898-1 IEC60947-2
Rated current 6A to 100A 10A to 2500A.
Interrupting rating Up to 18KA 10KA to 200KA
Trip Mechanism Thermal / Magnetic Thermal / Magnetic / Static
Trip characteristics Settings Not  adjusted Fixed /Adjustable

Thermal operated for overload and Magnetic operation for instant trip in Short circuit conditions

Application Indoor Type Indoor / Outdoor Type
Pollution Degree 0 to 2 3
Suitable for Low current circuits (homes, shops, school and offices). High power rating i.e. commercial and industrial use
User This is designed for unskilled user / uninstructed user and not being maintained consequently This is designed for skilled user and supposed to be maintained properly
Type of Protection over current protection over current / Short Circuit / Earth Fault  protection
Mounting Rail Mounted Rail / Fixed / Draw out Mounted
Operating Mechanism Electrical /Mechanical Operating Electrical /Mechanical / Motorized Operating
   untitled  22

 Example: what should we select MCB or MCCB for current carrying capacity 100A and breaking capacity 15KA and cost is a not main criteria.

  • For this rating both MCB and MCCB are available so we should consider application and other facilities to choose MCB or MCCB.
  • If we want to use it at indoor purpose, having less Space and if we do not need tripping adjustment  and other function or accessories than MCB is best option.
  • If we want to use it at indoor / Outdoor purpose, having Space and need tripping adjustment for coordination with other MCCB, We need Interlocking for safety and other function or accessories than MCCB is best option.
Characteristics IEC 60898-1 (MCB) IEC 60947-2 (MCCB)
Rated Current: In 6 – 125A 0.5 – 160A
SC Breaking Capacity <25kA <50kA
Rated Voltage: Ue 400V 440V, 500V, 690V
Impulse Voltage: Uimp 4kV 6kV – 8kV
Pollution Degree 2 3
Curves B,C,D B,C,D,K,Z,MA
Application Current AC AC or DC
Application Residential Residential / Commercial / Industrial

How to select MCB / MCCB (Part:2)

(C) Application Type:

(9) Utilization category / Characteristic (B, C, D, K, Z curve):

  • Characteristic of Trip curves of MCCB tell about the trip current rating of MCCB.
  • MCB will trip instantaneously according to their Tripping Characteristic at 0.1 sec.
  • There are various type of MCCB
  • Type B MCCB
  • Type C MCCB
  • Type D MCCB
  • Type K MCCB
  • Type Z MCCB


 Type B MCCB:

  •  Operating Current: This type of MCB trips between 3 and 5 times rated current (In).
  • Operating Time:04 To 13 Sec
  • For example a 10A device will trip at 30-50A. 
  • Application: Domestic applications or light commercial applications where connected loads are primarily lighting fixtures, domestic appliances with mainly restive elements.
  • Suitable for: Restive Load application (Lighting , Small Motor)
  • Surge Current: The surge current level is relatively low.
  • Installation at: At Sub feeder of Distribution Board.

   Type C MCCB:

  •  Operating Current: This type of MCB trips between 5 and 10 times full load current.
  • Operating Time:04 To 5 Sec
  • Application: commercial or industrial type of applications, fluorescent lighting, motors etc where there could be chances of higher values of short circuit currents in the circuit.
  • Suitable for: Inductive Load application (Pumps, Motor, fluorescent lighting.)
  • Surge Current: The surge current level is relatively moderate level.
  • Installation at: At incoming / Outgoing of Distribution Board.

Type D MCCB:

  • Operating Current: This type of MCB trips between 10 and 20 times full load current.
  • Operating Time:04 To 3 Sec
  • Application: specialty industrial / commercial uses (Transformers or X-ray machines, large winding motors, discharge lighting, large battery charging). Where current inrush can be very high.
  • Suitable for: Inductive- Capacitive Load  application (Pumps, Motor)
  • Surge Current: The surge current level is relatively High
  • Installation at: At incoming of Distribution Board / Panels.

Type K MCCB:

  • Operating Current: This type of MCB trips between 8 and 12 times full load current.
  • Operating Time:04 To 5 Sec
  • Application: Suitable for inductive and motor loads with high inrush currents.
  • Surge Current: The surge current level is relatively High
  • Installation at: At incoming of Distribution Board / Panels.

Type Z MCCB:

  • Operating Current: This type of MCB trips between 2 and 3 times full load current.
  • Operating Time:04 To 5 Sec
  • Application: These types of MCBs are highly sensitive to short circuit and are used for protection of highly sensitive devices such as semiconductor devices.
  • Surge Current: The surge current level is relatively too low
  • Installation at: At Sub feeder of Distribution Board for IT equipment.

(D) Accessories:

(1) Rotary Handle:


  • It is used to extend ON/OFF handle of MCCB when Panel Door is closed.
  • It is also used to indicate ON/OFF or Trip Position

(2) Shunt Trip:


  • Used for Remote Tripping

(3) Alarm contact:


  • It gives Tripping Indication when MCCB Trip.
  • It does not give when MCCB is in normal condition (either ON or OFF)

(4) Auxiliary contact:


  • It used for remote signaling and control purpose.
  • It is also give ON/OFF indication of MCCB at remote location.

(5) Under Voltage Tripping:


  • It used to trip MCCB in under voltage condition (70 to 35% of rated Voltage).

(6) Mechanical Interlocking:


  • It used to mechanical interlock of two MCCB on the same Panel.

(7) Manual / Auto:

  • MCCB may have provision for Auto /Manual operation.
  • An “auto/manual” switch in front of Panel.
  • When set to the “Manual” position, lock out electrical control and when set to “auto”, lock out the manual control; remote indication

(8) Motorized operation:

  • MCCB may have option for manual operation or with a motor mechanism for electrically controlled

How to select MCB / MCCB (Part:1)


MCB or MCCB are widely used in electrical distribution system for ON/OFF Electrical supply and it also gives over current and short circuit protection. Selection of MCB or MCCB involved technical, Mechanical parameters. Some parameters are important but some parameters are confusing and mislead to wrong selection of MCCB. Some parameters are directly affected on cost of MCCB.  

Specification / Name Plate Details of MCB/MCCB:

 Following specifications are required to select appropriate MCB or MCCB.

(A) Current Related:

  • Frame Size (Inm): Amp
  • Rated current (In/ Ie): Amp
  • Ultimate short circuit breaking capacity (Icu): KA
  • Rated short-circuit breaking capacity (Ics): % of Icu

(B) Voltage Related:

  • Rated voltage (Ue): Volt
  • Rated Insulation voltage (Ui): Volt
  • Rated impulse withstand voltage(Uimp): KV
  • No’s of Pole : SP,DP,TP,TPN,FP

(C) Application Type:

  • Utilization Category/ Characteristic : B,C or D curve

(D) Accessories:

  • Rotary Handle: Extended/ Direct
  • Alarm Contact:
  • Shunt Trip:
  • Under voltage Trip:
  • Mechanical interlocking:
  • Manual /Auto operation
  • Motorized Operation:

(E) Protection Type:

  • Protection : Over current / Short circuit
  • Trip Mechanism: Thermal / Magnetic / Solid / Microprocessor
  • Trip Mechanism adjustment : Fixed / Adjustable

(F) Others:

  • Frequency;
  • Reference temperature: (if different from 30°C)
  • Pollution degree:
  • Suitability for isolation:
  • Type of Mounting arrangement
  • Electrical Life Cycles:
  • Mechanical Life Cycles:
  • Dimension: mm
  • Weight: Kg
  • Reference Standard: IEC: 60947-1/2, IS: 13947-1/2

 (A) Current Related:

  (1) Frame Size (Inm): 

  • Breaker Frame Size indicates the basic framework of the Plastic shell of MCCB that can hold the biggest rated current.
  • It is the maximum current value for which the MCCB is designed (upper limit of the adjustable trip current range) and it also determines the physical dimensions of the device.
  • There are varieties current ratings MCCB for the same series frame Size.
  • For example, DX100 Frame Size MCCB for rated current of 16A, 20A, 25A, 32A, 40A, 50A, 63A, 80A, 100A.
  • Same DX225 Frame Size MCCB for rated current of 100A, 125A, 160A, 180A, 200A, 225A.
  • In above DX100 and DX225 has two Type of frame Size for rated current of 100A, but the shape and size of breaking capacity of circuit breakers is not the same.

 (2) Rated Current (In /Ie):

  • It is the current value above which overload protection is tripped.
  • For MCB it is fixed while in MCCB the rated current is an adjustable range instead of a fixed value.
  • Standard rating of MCB is 1A, 2A, 3A, 4A, 6A, 10A, 13A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, 100A for MCB.

(B) Voltage Related:

 (3) Ultimate short-circuit breaking capacity (Icu):

  • Breaking capacity can be defined as the maximum level of fault current which can be safely cleared.
  • It is the highest fault current that the MCCB can trip without being damaged permanently.
  • The MCCB will be reusable after interrupting a fault, as long as it doesn’t exceed this value.
  • It is indicate operation reliability of MCCB
  • This parameter may increase or decrease the cost, so it should be properly decided. Breaking capacity should be higher than the possible fault level. For domestic application fault level may be 10kA.

(4) Operating short-circuit breaking capacity (Ics):

  • It is expressed as a percentage ratio of Icu and tells you the maximum short-circuit current if a circuit breaker can break three times and still resume normal service.
  • The higher the lcs, the more reliable the circuit breaker
  • It is the maximum possible fault current that the MCCB can clear. If the fault current exceeds this value, the MCCB will be unable to trip and another protection mechanism must operate.
  • If a fault above the Ics but below the Icu occurs, the MCCB can interrupt it successfully but will need a replacement due to the damage suffered.
  • The Main difference between Ultimate Short Circuit (Icu) and Service Breaking Capacity (Ics) that Icu (Ultimate Braking Capacity) means Circuit breaker can remove the fault and remain usable but Ics (Service Braking Capacity) means Circuit breaker can remove the fault, but it may not be usable afterwards.
  • For example, if a circuit breaker has an Ics of 25,000 Amperes and an Icu of 40,000 Amperes:
  • Any fault below 25kA will be cleared with no problem.
  • A fault between 25kA and 40kA will cause permanent damage when cleared.
  • Any current exceeding 40 kA can’t be cleared by this breaker.

 (5) Rated working voltage (Ue):

  • It is the continuous operation voltage for which the MCCB is designed.
  • This value is typically equivalent or close to a standard system voltage.
  • In three phase it is usually 400V or 415 V. For single phase it is 230V or 240V.

(6) Rated Insulation voltage (Ui):

  • It is the maximum voltage that the MCCB can resist according to laboratory tests.
  • It is higher than the rated working voltage, in order to provide a margin of safety during field operation.

(7) Rated impulse withstands voltage (Uimp):

  • It is the value of transient peak voltage the circuit-breaker can withstand from switching surges or lighting strikes imposed on the supply.
  • This value characterizes the ability of the device to withstand transient over voltages such as lightning (standard impulse 1.2/50 μs).
  • Uimp = 8kV means Tested at 8 kV peak with 1.2/50μs impulse wave.

(8) Number of Poles:

  • No of Pole for MCCB depends on Single Phase & Three Phase Power Controlling /Protection
  • Single Pole (SP) MCB: 
  • A single pole MCB provides switching and protection for one single phase of a circuit.
  • Used: for Single Phase circuit
  • Double Pole (DP) MCB: 
  • A two Pole MCB provides switching and protection both for a phase and the neutral.
  • Used: for Single Phase circuit
  • Triple Pole (TP) MCB: 
  • A triple/three phase MCB provides switching and protection only to three phases of the circuit and not to the neutral.
  • Used: for Three Phase circuit
  • 3 Pole with Neutral (TPN (3P+N) MCB): 
  • A TPN MCB, has switching and protection to all three phases of circuit and additionally Neutral is also part of the MCB as a separate pole. However, Neutral pole is without any protection and can only be switched.
  • Used: for Three Phase circuit with Neutral
  • 4 Pole (4P) MCB: 
  • A 4 pole MCB is similar to TPN but additionally it also has protective release for the neutral pole. This MCB should be used in cases where there is possibility of high neutral current flow through the circuit as in cases of an unbalanced circuit.
  • Used: for Three Phase circuit with Neutral

What should you know before buying LED Bulbs (Part:3)

 (4) Color Rendering Index (CRI):

  • There are two standard measurements for the color characteristics of light: “color rendering index” (CRI) and “color temperature”, which expresses the color appearance of the light itself.
  • Color rendering index measures the ability of a light bulb to reproduce colors.
  • CRI is described How artificial light source is able to render the true color of objects as seen by natural outdoor sunlight which has a CRI of 100
  • The higher the CRI rating is, the better its color rendering ability.
  • Color Rendering Index (CRI) is a scale from 0 to 100.Incandescent bulbs are rated at 100 and most LED bulbs are usually rated somewhere between 80 and 85
  • CRI scoring of 100 is best and a CRI of zero being the worst.
  • CRI of 0: For a source like a low-pressure sodium vapor lamp, which is monochromatic compare to a source like an incandescent light bulb which has CRI of 100?
  • CRI of 62: A standard “cool white” fluorescent lamp will have a CRI near 62.
  • CRI of 70: Lamps with CRIs above 70 are typically used in office and living environments.
  • CRI of 82 to 86: Compact fluorescent lamps are graded at 82-86 CRI, which is considered high quality color rendering. CRI is a more important consideration for retail lighting design than it is for office lighting.
  • CRI of 80 and above: It is considered high and indicates that the source has good color properties.
  • Incandescent lamps and daylight have a CRI of 100, the highest possible CRI.
  • The higher the CRI of the light source, the “truer” it renders color.
  • The CRI can only be used to compare two light sources that have the same color temperature. A 5000 K, 80 CRI light source is not necessarily superior to a 4000 K, 70 CRI light source.
Color Rendering Index
Light source CRI
clear mercury 17
white deluxe mercury 45
warm white fluorescent tube 55
cool white fluorescent tube 65
deluxe warm white fluorescent 73
daylight fluorescent 79
metal halide 4200K 85
deluxe cool white fluorescent 86
metal halide 5400K 93
low pressure sodium 0-18
high pressure sodium 25
100-watt incandescent 100


Color Temperature & CRI
Lighting source Color Temperature Color Rendering Index
High Pressure Sodium Lamp 2100K 25
Incandescent Lamp 2700K 100
Tungsten Halogen Lamp 3200K 95
Tungsten Halogen Lamp 3200K 62
Clear Metal Halide Lamp 5500K 60
Natural Sun Light 5000K to 6000K 100
Day Light Bulb 6400K 80


Color Temperature & CRI
Kelvin Light Effect CCT CRI
Below 3600K Incandescent Fluorescent (IF) 2750 89
Below 3600K Deluxe warm white (WWX) 2900 82
Below 3600K Warm white (WW) 3000 52
3200K to 4000K White (W) 3450 57
3200K to 4000K Natural white (N) 3600 86
Above 4000 K Light white (LW) 4150 48
Above 4000 K Cool white (CW) 4200 62
Above 4000 K Daylight (D) 6300 76
Above 4000 K Deluxe Daylight (DX) 6500 88
Above 4000 K Sky white 8000 88

 (5) Beam angle:

  • How the light spreads out from the bulb (Beam Angle) is very important.
  • The beam angle determines how light is spread from the bulb into a given space.
  • The beam angle is the degree of width that light emanates from a light source. Specifically: The angle between those points on opposite sides of the beam axis where the intensity drops to 50% of maximum.
  • Typically a narrow beam angle is a ‘spot’ of light and called “Spot Light”. While a broader beam angle ‘floods’ with light, called a flood light. There are a number of much more specific designations of beam angle.
  • Beam angles of LEDs vary greatly and depend on their application. The shape of an LED bulb determines the direction light is emitted.
  • Narrow Spot Beam Angle: 05-15 degrees
  • Spot Beam Angle: 16-22 degrees
  • Narrow flood Beam Angle: 23-32 degrees
  • Flood Beam Angle: 33-45 degrees
  • Wide flood Beam Angle: 45+ degrees
  • Narrow angle bulbs less than 30 degrees are usually used when placing multiple down lights close to each other, such as in a hallway or when lighting cabinetry.
  • Larger beam angles are used with high-power LEDs for floodlighting. If you’re replacing incandescent or halogen lamps with LEDs, make sure the beam angle is similar to the old bulb.
  • Very large beam angles are sometimes found in pantries or walk-in wardrobes. As beam angle increases, we require more lumens (light output) to maintain the light’s intensity.


  (6) Efficacy (Lumen / Watt):

  • It is another important parameter to decide the performance of the LED bulb in terms of lumens.
  • It indicates effectiveness of the light bulb by converting electrical energy into visible light energy on watts used by Lighting Bulb; hence efficacy is total lumens per watt.
  • Example: 9W light bulb comes with lumens of 800 has an efficacy of 90 Lumens per Watt.
  • Incandescent bulbs give us light by passing electricity through a filament which heats up and emits light. In fact, 95% of the energy in these bulbs is lost to heat and only 5% is what produces light Hence, incandescent bulbs produce only 16 lumens / watt.
  • CFLs in the way they are built are more efficient and can give us between 50 to 70 lumens / watt (at least 3 times more than incandescent bulbs)
  • LED bulbs on the other hand, can output up to 100 lumens / watt – which make them one of the most efficient sources of lighting.
Parameter of LED Bulbs
Parameter Average Good Best
Lumens/Watt 75 90 100
Power Factor 0.7 0.8 0.9
CRI 60 70 80
LED Life in Hours 15000 25000 50000

 Other Technical Parameter:

(1) Instant Light:

  • LED Bulbs must be instant start and gives full Lumens from Starting.
  • When turning on CFLs and Fluorescent light bulbs, there is a slight hesitation before brightness is achieved, and some bulbs may flicker during warm up or even during operation.
  • Unlike fluorescents, LED bulbs, like incandescent bulbs, reach full illumination as soon as they are turned on.
  • LED lights produce a steady light which does not flicker.

(2) Dimming Capability:

  • Earlier versions of LED bulbs had the disadvantage of not being dimmable. Today, many LED bulbs are designed to work in dimmable switches which are provided in many lamps and home lighting fixtures.
  • Dimmable LEDs cost about 40% more than non-dimmable LEDs of similar wattage

(3) LED Driver:

  • The main cause of LED bulb failure is the driver. The driver is a small transformer that steps down the voltage from 230V AC to a much lower DC voltage for the LED.
  • It’s usually located inside the back of the bulb. A poor quality driver could result in bulb failure within months. The LED chip itself rarely fails until driver fails.

(4) LED Chip:

  • LED chips are manufactured by various big and small enterprises in the world. Some Good Suppliers make LED Chip of highest quality for longer life and more reliability.
  • Larger chip provide more lights, good stability against current variations, but it costs more.
  • Cheap and small led chip provides less light and stability. Ceramic COB lights are totally different in terms of size; they use multiple small chips to provide more lights and stability.

(5) Weight

  • LED lights need good heat dispassion, this can achieved by good amount of aluminum. Aluminum is generally used to provide better heat sink and extends the life of LED chip.
  • Thin heat sink can provide more area in less weight, but transfer enough heat for the removal.
  • Some lower quality products provide 12 to 20W lights in very low weight in plastic body. These products would not perform well even in small span of time.

(6) Heating:

  • Although LEDs don’t produce much heat they can overheat in operation if they’re not cooled correctly. Cheap LED’s are less efficient, produce more heat and are more heat sensitive. Operating above 60°C can damage cheaper LED’s shortening their life, reducing light output and efficiency. Generally the higher the wattage/power of a GU10 LED bulb, the more heat it produces requiring a more thermally efficient bulb body to keep the LEDs cool. Therefore beware of cheap higher wattage bulbs that don’t have a metallic or ceramic finned body. Another issue is that higher wattage thermally efficient LED bulbs may be so large that they are no longer a suitable size.

What should you know before buying LED Bulbs (Part:2)

(3) Correlated Color temperature (CCT):

  • Color temperature refers to the light’s color characteristics.
  • Color Temperature is measured in Kelvin.
  • It refer to the warmness or coolness of the light that bulb produces.
  • The color temperature of a light source is a numerical measurement of its color appearance.
  • This temperature is based on the principle that any object will emit light if it is heated to a high enough temperature and that the color of that light will shift in a predictable manner as the temperature is increased.
  • Color temperature is a description of the warmth or coolness of a light source. When a piece of metal is heated (temperature increases) the color of light it emits will change. This color begins as red in appearance and graduates to orange, yellow, white, and then blue-white to deeper colors of blue.
  • Color Temperature is not an indicator of lamp heat.
  • The sun, for example, rises in morning at approximately 1800 Kelvin and changes from red to orange to yellow and to white as it rises to over 5000 Kelvin at high noon. It then goes back down the scale as it sets in evening.
  • The warm white ranges from about 2700k to 3800k, natural white ranges from 3800k to 4800k, pure white or daylight from about 4800k to 6000k. Cool white starts from around 6000k upwards.
  • Colors and light sources from the red/orange/yellow side of the spectrum are described as warm (incandescent) and those toward the blue end are referred to as cool (natural daylight).
  • In Color Temperature Value higher Kelvin temperatures (3600–5500 K) are consider cool and lower color temperatures (2700–3000 K) are considered warm.
  • When choosing a color, the two considerations are important one is color rendering (How well the light shows the true color of objects) and temperature.

(1) Soft White / Warm White (2700K- 3000K):

  • Warm light is preferred for living spaces because it is more flattering to skin tones and clothing.
  • Recommended for indoor general and task lighting applications.
  • Living rooms
  • Bed rooms
  • Rooms decorated in earthy tones (reds, oranges, and yellows)
  • It gives effect like incident or halogen Light.

(2) Natural / Cool White (3500K- 4500K):

  • Cool light is preferred for visual tasks because it produces higher contrast than warm light.
  • Recommended for use in Domestic Applications.
  • Warmer Whites are preferable in living and dining areas as well as reception areas to create a more relaxed environment.
  • Natural Whites are preferable for kitchens and bathrooms where tasks are performed.
  • Suitable for work areas where contrast is important.
  • Kitchen
  • Bath rooms
  • Rooms decorated in airy, fresh hues (blues, greens, whites)
  • It gives effect like Fluorescent Light.

(3) Bright White (4500-5000K):

  • Recommended for use in:
  • Office
  • Study Room

(4) Daylight / Full Spectrum (5000K- 6500K):

  • Recommended for use in:
  • Garage
  • Office
  • Industrial and hospital areas.


                                                         Lighting Source CCT
Source Color temperature in Kelvin
Skylight (blue sky) 12,000 – 20,000
Average summer shade 8000
Light summer shade 7100
Typical summer light (sun + sky) 6500
Daylight fluorescent 6300
Xenon short-arc 6400
Overcast sky 6000
Clear mercury lamp 5900
Sunlight (noon, summer, mid-latitudes) 5400
Design white fluorescent 5200
Special fluorescents used for color evaluation 5000
Daylight photoflood 4800 – 5000
Sunlight (early morning and late afternoon) 4300
Brite White Deluxe Mercury lamp 4000
Sunlight (1 hour after dawn) 3500
Cool white fluorescent 3400
Photoflood 3400
Professional tungsten photographic lights 3200
100-watt tungsten halogen 3000
Deluxe Warm White fluorescent 2950
100-watt incandescent 2870
40-watt incandescent 2500
High-pressure sodium light 2100
Sunlight (sunrise or sunset) 2000
Candle flame 1850 – 1900
Match flame 1700
Skylight (blue sky) 12,000 – 20,000
Average summer shade 8000
Light summer shade 7100
Typical summer light (sun + sky) 6500
Daylight fluorescent 6300
Xenon short-arc 6400
Overcast sky 6000
Clear mercury lamp 5900
Sunlight (noon, summer, mid-latitudes) 5400
Design white fluorescent 5200
Special fluorescents used for color evaluation 5000
Daylight photoflood 4800 – 5000
Sunlight (early morning and late afternoon) 4300
Bright White Deluxe Mercury lamp 4000
Sunlight (1 hour after dawn) 3500
Cool white fluorescent 3400
Photoflood 3400
Professional tungsten photographic lights 3200
100-watt tungsten halogen 3000
Deluxe Warm White fluorescent 2950
100-watt incandescent 2870
40-watt incandescent 2500
High-pressure sodium light 2100
Sunlight (sunrise or sunset) 2000
Candle flame 1850 – 1900
Match flame 1700


                                CCT – Correlated  Color  Temperature

Kelvin Associated Effects Type of Bulbs Appropriate Applications
2700° Warm White, Very Warm White incandescent bulbs Homes, Libraries, Restaurants
3000° Warm White most halogen lamps, Slightly ‘whiter’ than ordinary incandescent lamps Homes, Hotel rooms and Lobbies, Restaurants, retail Stores
3500° White Fluorescent or CFL Executive offices, public reception areas, supermarkets
4100° Cool White   Office, classrooms, mass merchandisers, showrooms
5000° Daylight Fluorescent or CFL Graphic industry, hospitals
6500° Cool Daylight Extremely ‘white’ Jewelry stores, beauty salons, galleries, museums, printing




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


  • 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.
Lumen Chart for Incandescent, CFL,LED
Wattage Lumens Useful Lumens
LED 9W 800 lm 800lm
CFL 20W 1000lm 500lm
Incandescent 60W 1000lm 500lm
  • 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.
Area Lumens/Sq Meter
Kitchen 300 to 400
Kitchen (Task) 700 to 800
Living Room 400 to 500
Hallway 300
Bedroom 300 to 400
Bedroom (Task) 700 to 800
Bathroom 500 to 600
Bathroom (Task) 700 to 800
Reading Area 400

 (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.
Watt Approximate Lumens
25 Watt 230 to 270
35 Watt 250 to 410
40 Watt 440 to 460
50 Watt 330 to 450
60 Watt 800 to 850
75 Watt 1000 to 1100
100 Watt 1500 to 1600


Incandescent Watts CFL Watts LED Watts Lumens (Brightness)
40 8 – 12 4 – 5 450
60 13 – 18 6 – 8 750 – 900
75 – 100 18 – 22 9 – 13 1100 – 1300
100 23 – 30 16 – 20 1600 – 1800
150 30 – 55 25 – 28 2600 – 2800
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