While most people feel confident changing a standard bulb, a fluorescent light (sometimes improperly called neon tube) might be intimidating. Even I, although I rarely look for instruction, did a bit a research the first time I replaced one. The research did not last long though and you too will be amazed at how straightforward it is.
Be very careful not to break the tube, old or new, in the process. The chemical inside (mercury) is toxic. It must be disposed of properly.
1. Switch off
For safety reason, switch the light off. While you do not need to switch the entire power supply off for this operation (the light wall switch is enough, or if available the switch on the device), if you have any doubt I suggest you to do so.
2. Get a stepladder
It is likely that you will need a stepladder to reach the light. Even if you can touch it standing on the floor, it is better to make yourself comfortable and get a good look at the device.
3. Remove old tube
Reach for the tube and gently grip it with both hands. Now rotate for a quarter turn until it stops. This will rotate the socket in which the prongs sits and allow you to slide the tube downward.
Here is how the mechanism work:
The old tube is now removed. Please note the fluorescent tube are harmful to the environnement so avoid breaking it and dispose them properly (check with your local recycling service).
4. Install new
Slide the prongs new tube in the now open socket. Both sides at the same time. When it is in place, rotate the tube for a quarter turn to lock it in position.
5. Switch on
Now you may switch on the light (either at the device, wall or general power supply) and bask in the light your achievement.