Electrical noise ( I mean sound waves )

[planety_vuki]

Hello physicsforums. What causes noise in electrical cables and/or transformers and/or electrical stations ? By noise I mean mechanical sound waves like bzzzzzzzz, not signal noise. And what is the proper way to search in google for this, I could not find a wikipedia article on this.

 

[DrClaude]

Electric hum: http://en.wikipedia.org/wiki/Mains_hum

 

[planety_vuki]

thanks !