Fluorescent lamp fire danger

A fluorescent lamp or a fluorescent tube is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. A fluorescent lamps are widely used because they convert electrical energy into useful light much more efficiently than incandescent lamps (The luminous efficacy can exceed 100 lumens per watt). They are widely used in many commercial buildings because lower energy cost typically offsets the higher initial cost.

Fluorescent lamps have their benefits, but they have also problems. There are some well known health issues and also some safety issues. A recent issue that has up recently has been fire hazard. Finnish magazines Iltalehti and Turun Sanomat have written on it, and also insurance company “if” has issued a press release on this issue.

In theĀ press release main points are: In most fluorescent tube lies in the risk of fire, of which many have not been at all aware of. If the lamp should fail, it may become hot instantly over 200 degrees C and cause a fire. Easily replaceable malfunction sensing Safety lighter is cheap insurance to fire.

The articles and press release point to Tukes notes that a partially functional fluorescent lamp (flashing or dimly burning) can cause a sharp warming of fluorescent ballast. The luminaire components (ballasts and ends of the fluorescent lamp) can then become very quickly over a 200-degree hot. Safety and Chemicals Agency Tukes statistics show that the lamp is the second most common cause of electrical fires in Finland.

Here is circuit diagram of typical fluorescent lamp used in Finland: A preheat fluorescent lamp circuit using an automatic starting switch. A: Fluorescent tube, B: Power (+220 volts), C: Starter, D: Switch (bi-metallic thermostat), E: Capacitor, F: Filaments, G: Ballast

How to get rid of this danger? The easiest solution fluorescent lamps that use magnetic ballasts is that traditional igniters should be replaced with electronic safety igniter. This solves the whole problem easily and fairly cheaply (just few euros more expensive than traditional igniter): electronic igniters try to light tube tube a limited number of times and thus heat lamp electrical parts (ballast, tube and lighter).

Other solution is to replace the lamp with newer model that uses electronic ballast that has built-in safety functions.

Third option that comes to my mind is to replace the fluorescent tube with LED tube designed to replace fluorescent bulb. It does not need the igniter. Tukes has written notes on replacing fluorescent lamps with LEDs. Also Valtavalo has written a press release on this replacement.


  1. safety says:

    Hello, after reading this remarkable post i am too glad to share my know-how here with colleagues.

  2. Mammaran says:

    The fluorescent tube was removed two weeks ago but the power supply was in “ON” position. Will this condition heat-up the tube holders and start a fire? Your immediate response would be appreciated.

    • Tomi Engdahl says:

      When you have fluorescent tube removed, this essentially makes the whole lamp circuit open circuit.
      So when the tube has been removed, there will be no current floating on normal lamp circuit and no heating of tube holders.

      The heating is only generated when tube is in place: the heat is generated inside the tube itself – there are the heating wires inside it that should normally be heated just for a short time when the tube starts. When there is no tube, there are no such parts that generate heat.

  3. Tomi Engdahl says:

    How a Fluorescent Lamp Turns On

    I was always vague on how a fluorescent lamp worked, so I did some research!

  4. Tomi Engdahl says:

    Many fluorescent lamps also have a capacitor on the power input in parallel with the incoming power.
    Those capacitors also tend to age.
    First they tend to loose capacitance, that’s not that bad.
    But they can also fail over time so that they can start heating and putting out smoke – fire hazard.


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