Recently installed a new Multiplus 500 into my caravan and up to now I've been running off grid. Before going away I've tried the grid connection and noticed that the Multplus buzzes. It's not loud but is noticable at night. The buzzing does tend to change depending on the 230v load.
I'm now thinking of relocating the in Multiplus which will means longer 12v battery connection but it may mean I can sleep better
Is the buzzing normal as I thought that when on grid the Multiplus was effectively bypassed?