Les Ward
Hi Kerry, If you switch off all the circuit breakers on your consumer unit followed by the main switch and the humming sound is still present you can be quite certain that the electrical circuits and devices in your property are not contributing to the sound. Switch the electrics back on in reverse order, main switch first. The sound may be coming from a neighbouring property or it may be the phenomenon of "low frequency noise" or "infrasound", which despite much research and theorising remains a scientific enigma.
