The Truth About LED Light Bulbs

The Truth About LED Light Bulbs

LED bulbs have all been over-priced, over-complicated and underperformed customers expectations. Until now. 

At Casell Lighting we believe that buying a light bulb should not be this complicated! All anyone wants is an LED replacement for a 100w, 60w, 50w, 40w or 25w standard light bulb (GLS), candle, golf ball or spot light (either halogen gu10 or incandescent reflector). 

But the LED lighting industry likes to make everything complicated. Suddenly the light bulb shapes are slightly different, the new LEDs are often slightly bigger than the original, old bulbs. 

WHY? The reason is that LEDs still get hot and the new bulbs need to fit the LED chip and a heat sink (to reduce heat) to make the bulbs work. 

BUT – customers hate bulbs that suddenly appear bigger in their light fittings! 

At Casell, all our LEDs are the same dimensions as the original bulbs that they are designed to replace. Casell LED Range


The old incandescent and halogen bulbs were easy. They all worked on dimmers. It was not something any of us had to thing about. But LEDS are not normal…they all need a lot of help to actually dim and to dim nicely. Not in a jerky way but in a smooth way. This is where customers have to keep a look out on what they are buying as most, cheap LEDS will not be dimmable at all! 

Where possible ALL of our CASELL LEDs are dimmable and are compatible with 95% of dimmers available in the UK. 


Customers want to understand the wattage, this is the way we have always purchased light bulbs. But everyone must remember that wattage merely shows how much energy is consumed by the light bulb. In the world of LED, the energy consumed is a lot less so it is very hard to give a standard wattage equivalent to the old 100w, 60w etc. Below is where things stand currently: 

  • 100w = 10w 
  • 60w = 5w or 5.5w 
  • 50w = 6w or 5.5w 
  • 40w = 3.5w or 4w
  • 25w = 2.5w or 3w 

To compare how bright light bulbs are now we really need to look at their LUMENS. 


A Lumen (lm) is the International Standard unit for the total amount of visible light emitted from a source. Like Watts, Lumens are a standard measurement within the lighting industry and can be found on the box of most light bulbs. 

The information below shows the typical Lumen levels expected from traditional incandescent bulbs. 

  • 40w incandescent = 380 – 460 Lumens 
  • 60w incandescent = 750 – 850 Lumens 
  • 75w incandescent = 1100 – 1300 Lumens 
  • 100w incandescent = 1700 – 1800 Lumens 
  • Direct sunlight = 100,000 Lumens 

The information below shows the typical Lumen levels expected from LEDs. 

  • 5w LED Candelabras = 400 Lumens 
  • 7w LED A19 = 600 Lumens 
  • 12w LED PAR30 = 850 Lumens 

As you can see by comparing the above tables, LEDs are able to produce high Lumen levels with comparatively low wattage consumption. In fact, LEDs are able to produce up to 110 Lumens per Watt, whereas, incandescent only produce 12-17 Lumens per Watt. 

So next time you choose a light bulb, remember to consider both Watts and Lumens. Watts measure the amount of electricity used and Lumens determine the ‘brightness’ of a bulb. The ideal combination being: 



This is where the must stress comes from. Most customers want a warm white light, as similar to the old incandescent bulbs as possible. BUT all LED bulbs have LED chips that naturally start off giving out a blue light. 

To make it give a warm white (same as old incandescent bulbs) you need to tweak it, this is where things get complicated, but the technology can do this. Our Casell bulbs are as close to warm white as we can make them. 

BUT not all LEDs that claim to be warm white actually give off that colour! 

Unfortunately lots of LED manufacturers claim this but few get tested. 


This is a measure of how warm or cool the light given off by a fluorescent lamp appears, with warmer colours having a yellowish tinge and colder colours appearing a lot brighter. What confuses some people is that the warmer a colour is, the colder its colour temperature is. This is because something which is red hot is actually colder than something which is white hot (which makes sense when you think about it) but psychologically the bluish white object seems colder as we associate blue with cold. 

Here at The LAMP Company all our offices and work areas are fitted with 6500k lamps. It helps provide the staff with better light levels and it is deemed to appear a much nicer atmosphere. 


Colour temperature is measured on the Kelvin (K) scale, which uses the same units as the Celsius or Centigrade scale, but starts at absolute zero (-273 degrees Celsius) 

A warm white lamp similar to an incandescent bulb, including halogen, has a colour temperature of around 2700K, and gives off light with a yellowish quality, while 5000-6500K represents a bluish white colour as shown in the colour guide. 

The most common colour temperatures available are as follows: 

2700K is classed as extra warm white and is common in many of the lamps available from supermarkets, DIY sheds and the free ones given away by energy companies. However, this colour has done more damage to the use of CFLi’s due to many retailers selling inferior quality items 

causing headaches, poor lighting and in some cases short life. At the Lamp Company we only stock reputable quality lamps with this rating. 

3000K is still classified as warm white, but is slightly colder than 2700K and mimics a halogen lamp. 

3500K is bulk standard white and has been around for over 70 years. Popular in warehouses, corridors, offices and many other applications where people are situated. Half our warehouse is in white and the other half in Daylight. It looks strange but it’s used in many editorials. 

4000K is classed as cool white that is often used in office buildings, and you might consider it for a home office to give a more professional feel. It will also appear brighter that White and warm white. 

5400-6500K lamps are often branded as daylight bulbs, having a similar quality of light to a hot summer's day with a blue sky. This is a very cold light that would not usually be used in the home, but may be helpful for people with Seasonal Affective Disorder. (SAD) 

Colour Rendering Index (CRI) 

This is a measure of how realistic colours look when they are lit by a lamp. A standard incandescent bulb scores 100% as it produces the full spectrum of colours and therefore has perfect colour rendering. 

If you want colours to look good, you need to choose an LED bulb with a CRI of 80% or higher - this will be fine for everyday use. Very few LEDS have a CRI higher than 90%. 


Yes – LEDS last a long, long time. BUT, what happens is that the heat generated by the chip in the back of the bulb gradually erodes the quality of the light output. Typically what happens next is that the warm white colour it originally gave off fades back to the normal blue colour of the chip. So whilst the light bulb is still working, not many household customers are happy to have blue lights in their ceilings! 


This is why we do a lot of testing to making sure the LEDS that we make are SAFE and will give the correct colour for the life of the bulb. It costs us money and time but we think it is the right thing to do. 

Looking for a new LED Light? Get in touch with us and we will happily guide you in the "bright" direction.

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