Could a relay switch be causing the havoc in my home?

[EalingBadger]

Try to eliminate the dimmers, put normal switch's in place if the interference goes away well and good, if not then move on to the next possible source, the bulbs themselves, I have found that non mains LED's cause more problems than they are worth, especially the transformers, now there's a thought.

The "transformers" (in reality poor quality switched mode power supplies more often than not) are renowned for being electrically absolutely filthy.