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Understanding Lighting: Decoding Bulb Specifications

When Abbeygate Lighting opened its doors in 1980, purchasing a light bulb was a simple task. Options were limited to 25, 40, 60, or 100 Watts, primarily in British Bayonet Cap (B22). However, with the rise of Fluorescent and LED bulbs, the landscape has changed, introducing a plethora of new codes and symbols.

Today, deciphering bulb specifications involves understanding key symbols found on packaging:

  • W (Wattage – measure of power consumption)
  • V (Voltage – most bulbs run on 240V, which is UK mains, but some may be lower, most commonly 12V, usually in kitchens or bathrooms)
  • Lm (Lumens – A measurement of the light emitted from the lamp)
  • K (Kelvin – Colour temperature)

In older bulbs, the wattage was a good indicator of the brightness – a 60W light bulb is as bright as any other 60W bulb. However, once more efficient forms of light bulbs became available, the wattage was augmented by Lumens. This more accurately reflects how much light the bulb is emitting rather than how much power it is using.

For example, an 8W LED bulb uses far less power than a 60W incandescent, but they are both emitting roughly 800Lm, meaning they have the same brightness. Helpfully, many manufacturers include a key on the packaging – 9.6W can look daunting, but 9.6W=75W gives the customer a clearer idea of how bright the LED bulb will be, by equating it to a more familiar scale.

Finally, Kelvin is used as a measure of the colour temperature, often referred to as either a Warm White, Cool White or Daylight. In simple terms the higher the number, the closer the light colour is to a daylight white.

Often Warm White light (around 3000K) is used in cosier settings, such as living rooms and restaurants, to evoke a warmth similar to candlelight. Cool Whites, in the middle of the spectrum (around 4000K), are more commonly used in kitchens and bathrooms, and can be referred to as Task Lighting, where general ambience is less important than clear lighting for – tasks!

Daylight White is higher up on the spectrum still (around 6500K) and is a more specialised application – Often sought after by artists and designers, this spectrum helps preserve true colours by replicating the light from the natural sky. It is also helpful for providing contrast to letters on a page, which is why many reading lights use this colour temperature to aid those with weaker eyes.

All these terms and definitions are designed to help identify the best light bulb for your purpose, and as the market updates and adapts they should provide an easier checklist for you.

At Abbeygate Lighting, we understand that these terms can be confusing, and it is our business to know and understand them. So, if you are feeling overwhelmed and would like a 60W Push-and-Twist light bulb for a reading light, just ask us.

We will know what you mean.