Choosing a Fluorescent Tube

Sometimes it’s not easy to pick the right fluorescent tube for your application. Here’s a rough guide to help you choose.

There are 3 important factors when choosing a fluorescent tube:

  1. The diameter
  2. The length
  3. The colour rendering (see our Colour Temperature and Colour Rendering Index Guide)

Watch our video guide to measuring and identifying a fluorescent tube

Fluorescent Tube Diameter

Firstly measure the diameter of the tube. There are 4 types listed on our website.

T2 fluorescent tubes, T4 fluorescent tubes, T5 fluorescent tubes and T8 fluorescent tubes. There are also T12 tubes available but these are being phased out under the EU Directive. If you require more information about these please call our sales office or visit our trade site to find these T12 tubes

The number signifies the diameter of the tube in eights of an inch. For example T5 is 5/8th’s of an inch in diameter or as shown on our site 16mm. Now there is not a lot of difference between T4 & T5 but T4’s can generally be identified as they have a plastic end cap rather than metal. T4 tubes are notoriously difficult to identify with some manufacturers items being a couple of millimetres different. Not easy to measure with a 300mm ruler.

Fluorescent Tube Length

Once you have selected the diameter the next stage is identifying the length. For length it is imperative to measure your tube to the end of the tube including the pins. Sometimes it is easier to use a tape measure than a small ruler.

Fluorescent Tube Colour Rendering

Then to the colour. Halophosphate tubes are obsolete in T8 diameter although we still have good stocks left. These items are generally just White/35 or Coolwhite/33. For the triphosphor equivalents please visit our colour temperature/rendering guide


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