I know other posters have mentioned the homeplugs - I use them all around the (not so small) house and it gives me effectively a lan outlet in every room.
I have the box in front of me:
- a portable ethernet cable
- faster and easier to set up than wi-fi
- transform power socket into network point
- no problems with thick walls and blind spots
- perfect for home networking
I am not sure how the "phases" which has been mentioned affects me and the box doesn't stipulate anything about the electrical circuit but it just works and works well, exactly as described on the box.
(edited for ridiculous typo..)