This morning I became aware of a little clicking noise coming from my inductive phone charger. I realised I'd been hearing it for a while. While I was changing, I noticed a high-pitch noise coming from my wife's Sony charger. Then later in the kitchen, a buzzing noise coming from the socket the microwave was connected to. All around the house, various sockets buzz.

Is this normal? I've checked my voltage using a meter plug, and it fluctuates between about 236.5 and 237.5*, which is normal enough according to the electrical company (who's operating range is 207 - 253 Volts)

*Before anyone freaks out, I'm in Ireland. We use 230v electricity over here.

  • When's the last time you had your hearing checked? Maybe you're able to hear some frequencies that "normal" people cannot. Does anybody else hear it? Have you been involved in any toxic waste spills, exposed to gamma radiation, or come into contact with any meteorites? From what I've been told, cats and dogs can hear the hum of electricity. Have you been bitten by any wild "dogs" during a full moon?
    – Tester101
    Mar 5, 2014 at 11:28
  • That first paragraph sounds like the opening of a bad horror movie! Mar 5, 2014 at 14:00
  • Both of you guys behave yourself! Or we will get edited!!
    – Jack
    Mar 5, 2014 at 14:47
  • fear the wrath of.... THE EDITOR
    – roryok
    Mar 5, 2014 at 16:53
  • Aluminum wiring by any chance? May 18, 2015 at 19:35

2 Answers 2



The sound you're hearing, is likely caused by transformers. It's a common problem, and a normal phenomenon.

Most wall warts consist of a transformer to reduce the voltage, and a rectifier to convert alternating current to direct current. So anywhere there's an AC adapter, there's likely a transformer.

This document from Federal Pacific (PDF), explains the phenomenon that causes transformer hum well.

Transformer noise is caused by a phenomenon called magnetostriction. in very simple terms this means that if a piece of magnetic sheet steel is magnetized it will extend itself. When the magnetization is taken away, it goes back to its original condition....

A transformer core is made from many sheets of special steel...

If the extension and contractions described above are taking place erratically all over a sheet, and each sheet is behaving erratically with respect to its neighbor. You can get a picture of the moving, writhing construction when it is excited. Of course, these extensions are only small dimensionally, and therefore cannot usually be seen by the naked eye. They are, however, sufficient to cause a vibration, and as a result noise...

Loose Connections

If you're hearing the buzzing from receptacles (sockets), it could be caused by a loose connection. If a connection in the receptacle is loose, there could be arcing taking place. Arcing could definitely cause an audible sound. However, arcing would also generate heat, which could lead to a fire. It's best to contact a local Electrician to come have a look. If you're familiar and comfortable with electrical work, you could check the connections and/or try replacing the receptacle (socket).

  • Thanks, the buzzing only comes from sockets when something is plugged into them, and turned on. It's most likely the actual device I'm hearing, not the socket.
    – roryok
    Mar 5, 2014 at 16:54
  • 1
    @roryok not necessarily; arcing happens when power goes through a gap (caused by bad connection), if there is no power draw then there will be no arcing, I'd still check the connections Mar 6, 2014 at 10:59

The same thing has happened in our house. The noise was coming from electrical sockets on the second floor. It rotated from room to room. Finally I got some advice to check all the alarms in the house. The problem was caused by a disfunctional carbon monoxide alarm. When we unpluged the alarm, the noise stopped.

  • See @ratchetfreak's comment above re: series arcing on bad connections -- it's likely the outlet your CO alarm was plugged into has a bad connection to it. May 18, 2015 at 22:34

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