What is the frequency of mains electric noise in the uk?
It seems to me you will find both 50Hz and to a lesser degree, 100Hz. I'm having difficulty recalling if 100Hz is confined to internal lines where there are more devices employing rectification to DC, with ripple, or if the octave is commonly developed to a small degree within external structures as well.
Harmonics of the primary frequency will certainly dominate, but switching noise has no particular spectrum. Total harmonic/distortion spectrum analyzers will give useful indication.
Part of the difficulty in answering this question in any definitive way is due to the non-specific nature of the word "mains". The UK, like most well-developed countries employs 3-phase distribution on some legs of the "pipeline" but at some point this gets divided and 2-phase is what is common, in some locations for many miles. I suspect the different phase angles will cause different harmonics.
The mains frequency is 50Hz in the UK. There is no one frequency for the noise on the mains as the sources are varied and can include quite narrow pulses.
Google found an example..
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