I'm a fully registered electrical contractor.
They should work across any circuits in the property, using your consumer unit (fusebox) as the bridge between the circuits.
I am planning to use some next week to send 8 number video camera feeds from a first floor recording and control unit to a ground floor monitor/mouse/keyboard set up.
Try Maplins website and they will give you online answers to any application/setup questions you may have.
Knowing how it works is completely different to understanding how it works.