Common Faults and Treatment Methods of Fluorescent Lamp

A low-pressure mercury vapor gas discharge lamp that uses fluorescence effect to produce visible light is known as fluorescent lamp or fluorescent tube.

There are some common faults in case of the fluorescent lamps. These faults, their reasons and treatment methods are described in the following table −

Type of FaultReasons of FaultTreatment or Repairing Methods
The fluorescent lamp does not start.
  • Loose and defective holders.

  • Defective fluorescent tube.

  • Defective starter switch.

  • Defective choke.

  • Turn the tube through 90° and check the connections and holders.

  • Replace the tube.

  • Try another starter switch / replace the starter switch.

  • Replace the choke.

Fluorescent lamp blinking ON and OFF
  • Loose contacts.

  • Wrong circuit connections.

  • Low supply voltage

  • Defective starter.

  • Defective fluorescent tube.

  • Check all the connections.

  • Change the ballast tapping if required.

  • Replace the starter switch.

  • Replace the fluorescent tube.

Sometimes the ends of the fluorescent tube remain lighted.This fault is due to short-circuited starter.Check the starter switch and replace it.
Blackening of the end portions of the fluorescent tube.This fault occurs due to too low or too high voltage.To resolve this fault, adjust the ballast tapping if provided.
Dark streaks along the fluorescent lamp.It is due to mercury globules (or droplets).To correct this fault rotate the fluorescent tube by 180°.
Snaking spiraling. (This fault occurs with the glow type starter.)This fault occurs due to either opening of the starter switch quickly or wrong tapping made on the ballast.
  • To resolve this fault, replace the starter or ballast.

  • In case of new fluorescent tube, this fault automatically cures after few days.

Burn out electrodesThis fault occurs due to short-circuit of the choke.Test with a new choke.
The brightness of the fluorescent lamp decreases.
  • Low power supply voltage.

  • Aging of the lamp tube.

  • If the power supply voltage is low, then check the power supply and correct it.

  • If lamp tube is aging, it needs to be replaced with a new one.

Large electromagnetic noise from the choke.It is mainly due to poor quality of the ballast and the large vibrations of the sheets of the iron core.Re-tighten the iron core of the choke if possible, otherwise replace it.
Choke overheating
  • Poor ventilation and heat dissipation.

  • Inter turn short circuit of the internal coil of the choke.

  • Provide proper ventilation and heat dissipation.

  • If inter-turn short-circuit, then replace the ballast with a new one.

Updated on: 05-Apr-2022

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