Every home has a range of electrical products that cause interference & pollutants to enter the mains supply. These range from simple fluorescent lights, and include most other humble domestic appliance’s using switching power supplies. LED lamps and dimmers are particularly bad for polluting the mains with high frequency interference.
An inherent problem with three phase electrical systems is the level of “stray voltages” which are invariably present. Excess power or energy is returned to the ground or earth point, where it is joined to the earth in the fuse box or / and additionally to the protective ground.
This interference, from a music lover’s perspective can severely affect the sound quality of the music lover’s system/setup as it can litter the ground/earth plane with noise & also create strong, stray magnetic fields.