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How To Know You Are Buying The Right Bulb?

Sometimes is can be confusing when it comes to buying the right bulb so we have created this step by step blog full of information to help you get a better understanding of what you need to know when it comes to buying the right bulb. 

First of all you need to determine what fitting or cap type you need if you choose the wrong fitting or cape type your bulb will not fit this is the most common mistake people do when finding the right bulb. Caps are labelled with both letters and numbers, the letters are used to indicate the type of base and the numbers indicate the diameter of the base.

The most popular cap types in uk homes:

Edison Screw Cap

ES-E27 Cap
Diameter: 27mm
Height: 26mm
The most popular ES or E27 fitting is 27mm diameter and is widely used in the UK and europe. This cap is the standard 27mm diameter screw cap for UK 240V light Bulbs. 

SES-E14 Cap
Diameter: 14mm
Height: 26mm
The SES or "small edison screw" cap is often used for smaller decorative fittings, chandeliers and appliance light bulbs i it has a diameter of 14mm and is prominently used in the UK and europe. 

Bayonet Cap

BC-B22 Cap
Diameter: 22mm
Diameter: (pin to pin): 27mm
Height: 26mm
With its familiar push and twist action, the bayonet cap is also known as BC or B22 cap is used on most regular light bulbs. it is 22mm in diameter and with two locating lugs.

Capsule Lamps 

G4 Base 
Distance pin (centre) to pin (centre): 4mm
The G4 is specifically used for 12V capsule light bulbs. These capsules require a 12V transformer or driver to operate - this is usually built into the fitting. The capsule can be identified by measuring the distance between the centre points of the pins. The distance of a G4 measures 4mm. 


G9 Base
Distance pin (centre) to pin (centre): 9mm
the G9 is specifically used for 240V capsule light bulbs. The light can be identified by measuring the distance between the centre points of the pins. The distance of G9 measures 9mm. 

Halogen and LED Spotlights

GU10 Cap
Type: twist and lock
Distance pin (centre) to pin (centre): 10mm
Featuring two pins that twist and lock the spotlight into the fitting, the GU10 is the most popular spotlights used in the uk. The spotlight is mains operated 240V and was initially developed as a halogen spotlight but is not widely available in LED. Various wattages, colour and beam angles can now be purchased to provide lighting in many different applications. 

Halogen light bulbs will be banned from September 2021 with fluorescent light bulbs to follow, cutting emissions and saving consumers on their energy bills.


The second step is to decide if you want CFL, Halogen or LED. CFL (compact fluorescent lamp) are cheap and widely available in many different sizes and output they are much more efficient than incandescent bulbs and more energy saving but not everyone likes the kind of light they admit. The halogen is more expensive to run than other energy saving bulbs with an expected life span of 2 years they also admit a lot of heat. LEDS (light emitting diodes) use almost 90% less energy making them the most energy-efficient type of lighting by far they are initially more expensive than other bulbs but they last up to 25 years so in the long term they are the cheapest option.

Your third step is to consider the brightness and colour this breaks down into 
Watts and Lumen output. The wattage of the light means the amount of energy it takes to produce a certain amount of light. The higher the wattage the brighter the light and the more power it uses. Lumens means the amount of light/brightness a bulb gives off. 


What Lumens do you need? 

Room Lumens Recommended per square metre
Living Rooms and Bedrooms 35
Hallways 15
Kitchens and Dining 50-70
Bathrooms 120-135


Compare the watts to the lumens 

Efficiency  Least Most
Bulb Type  Standard  Halogen CFL LED
450 Lumens 40W 29W 9W 6W
800 Lumens  60W 42W 14W 9W
1100 Lumens  75W 53W 18W 11W
1600 Lumens  100W 72W 23W 14W



Colour Temperature Chart

Colour temperature is measures in Kelvin (K) scale, which uses the same units as celsius or centigrade scale. 

Offers a soft glow and adds ambience.
Warm White 
standard colour for inviting and warm lighting.
Neutral White
Bright and Vibrant, for staying focused.
Invigorating and sharp, for areas with specific tasks. 
Example uses: Table lamps and floor lamps. Example uses: Living rooms, bedrooms, dining rooms, wall and ceiling lights. 
Example uses: Garages, work settings, basements, task lighting, kitchen, home offices and bathrooms, 
Example uses: Display areas, security lighting, garages. task areas, studying and reading areas. 

The most common colour temperatures are as followed: 

  • 2700k is classed as extra warm white.
  • 3000k is still classified as warm white, but is slightly cooler than 2700k and mimics a halogen lamp.
  • 3500k is bulk standard white.
  • 4000k is classed as cool white.
  • 5400k - 6500k lamps are often branded as daylight bulbs. 

Advantages of LED light bulbs

Having a LED bulb has a muted reduced energy use than other bulbs which becomes a lot more efficient for example the use 75% less energy and emits very little heat compared to a incandescent bulb which releases 90 percent of their energy as heat and CFLs which release about 80% of their energy as heat. A good LED light bulb theoretically has a lifespan of 25,000 plus hours whereas an incandescent bulbs have a life span around 1,000 hours. 

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  • Jan on

    I am thinking of buying the aurolite outdoor wall light, it states e27 bulb cap but I’m not sure what bulb to get can you please advice.thanks

  • Jan on

    I am thinking of buying the aurolite outdoor wall light, it states e27 bulb cap but I’m not sure what bulb to get can you please advice.thanks

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