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—What you are noticing

When a light or switch buzzes

A faint hum from a dimmer is common. A buzz from a switch that also feels warm is not. The difference is worth knowing.

Many lighting components make a little noise. Dimmer switches can hum, especially with lamps they were not designed for. LED drivers and transformers can whine faintly. Fluorescent fittings with older ballasts often buzz. None of these is necessarily a fault, though a mismatched dimmer and lamp combination is worth correcting.

This guide describes what people notice and what is safe to do. It does not diagnose your installation; only someone who has seen it can.

A buzz that is new, getting louder, or coming from a plain on-off switch or a socket is different. Sound from a connection usually means current is jumping a gap that should be a firm contact, and that generates heat. If the buzz comes with warmth, discolouration, flicker or a smell, the circuit should be switched off and the point checked.

01In short

The points that matter most

  • Dimmer hum is common

    Often a lamp and dimmer that do not suit each other.

  • Switch or socket buzz is not

    Sound from a connection usually means a poor contact.

  • Heat changes everything

    Noise with warmth or smell is a reason to switch off.

02Detail

Where the noise usually comes from

  • Dimmers

    Electronic dimmers can hum under load or with incompatible lamps; the right dimmer type often quietens them.

  • Drivers and transformers

    LED drivers and low-voltage transformers may whine, particularly as they age or when overloaded.

  • Connections

    Loose terminals in switches, sockets or junction boxes can buzz as current arcs across them.

03Checklist

Before you call

  • Locate the sound

    The switch, the fitting, the ceiling or the board.

  • Feel the faceplate carefully

    Touch the plate only, briefly, to see whether it is warmer than others.

  • Note the lamps and dimmers

    Type and brand help if a compatibility issue is suspected.

04Questions

Questions people ask

Is a humming dimmer dangerous?
Usually not, but it can indicate the dimmer and lamps are mismatched. It is worth correcting.
Why does my LED fitting whine?
The driver inside can whine, especially with certain dimmers or as it ages.
Can a buzzing switch be fixed easily?
Often by repairing or replacing the switch and its connections, once the circuit has been safely isolated.

05Related

Related guides

This guide sits under troubleshooting. All topics are on the guides page.

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