To hopefully reduce any mains borne interference and to mitigate against the possibility of putting RF into the mains supply, I recently built two mains filters by copying the design published by Ian White GM3SEK in his technical blog. The filters are now feeding two 10 Way surge protected 13 amp distribution panels in my shack:
Fair-Rite ferrite clamp on cores low & BB Freq 31 Mat (Bought Jan 2019)
Fair rite ferrite cable cores 43 Full flat cable core (2 needed per filter)
Schaffner power line line filters 16A fast-on (1 per filter)
2 X Hammond RL6465-F Flanged ABS wall mount instrument enclosure 150L X 100H X 90W - box width very tight - only just accomodates ferrite filters when wound.
Schneider Electric GGBL3010S LWM 1 gang 13A switched mains socket
CPC: PL10035 EXT LEAD 10 GANG WITH SURGE + RFI X 2
Cable - domestic appliance sized 3 core mains cable - I had that in stock. The large Fair-Rite clamp on ferrite just accommodates 7 twisted turns of that sized cable. Any thicker and you would struggle to get 7 turns through the middle.
Volt drop through the filters off load when tested is approx 1 volt - 232V in 231V out.