What is the cause of this sound from the tube light?

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Discussion Overview

The discussion revolves around the cause of a sound produced by a tube light when it is switched on. Participants explore potential reasons for this sound, focusing on the role of the ballast and terminology differences related to its function.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant describes a persistent sound from a tube light that stops after about half an hour, seeking the cause.
  • Another participant suggests that the sound may indicate a failing ballast and recommends swapping the light tube with another fixture.
  • A follow-up response confirms that changing the fixture stopped the sound, prompting further questions about the ballast's function.
  • A participant explains that the ballast converts AC mains power to high voltage for the fluorescent tube and can produce a buzzing noise when failing.
  • Some participants discuss the terminology of "ballast," with one noting that it may refer to a series inductor used to limit current in the discharge tube.
  • There is mention of potential differences in terminology across regions, with a participant referencing local electrical terminology.
  • Another participant adds that resistors or filament bulbs were historically used as ballast in common fluorescent tubes.

Areas of Agreement / Disagreement

Participants express differing views on the terminology and function of the ballast, indicating a lack of consensus on its definition and role in the context of tube lights.

Contextual Notes

There are unresolved assumptions regarding the specific type of ballast and its operational characteristics, as well as the historical context of terminology used in different regions.

Wrichik Basu
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I have a tube light at my home which produces this sound:



The sound can be heard for a long time every time the light is switched on, but it stops after about half an hour of switching on the light.

What is the cause of this sound?
 
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Sounds like the ballast is going bad. Do you have another similar light fixture that you can swap the light tube with?
 
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berkeman said:
Sounds like the ballast is going bad. Do you have another similar light fixture that you can swap the light tube with?
Yes, I changed the light, but the sound continues.

As you are saying, I also changed the fixture, and the sound stopped.

What does this show? And what is the ballast?
 
Wrichik Basu said:
And what is the ballast?
The ballast takes the AC Mains power in (120V or 240V, etc.), and converts it to the high voltage used to turn on the florescent tube. It is basically an inexpensive switching power supply, and when it starts to fail, it can make an audible buzzing noise.
 
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berkeman said:
The ballast takes the AC Mains power in (120V or 240V, etc.), and converts it to the high voltage
I thought that the term "ballast" was used for the series Inductor that's used to limit the current flowing through the very low resistance of the discharge tube, once it has struck. But I am referring to the ordinary domestic flow tubes which strikes easily with mains volts after the starter circuit has heated the filaments at each end and produced its thermionic electrons.
 
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sophiecentaur said:
I thought that the term "ballast" was used for the series Inductor
It could just be a difference in terminology country-by-country. The Wikipedia article follows the US terminology, I think. :smile:
 
Also the terminology of the man in the local electrical factors in Essex.
Sometimes a resistor or even a filament bulb was used as 'ballast' for a common or garden fluo tube.
 

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