I was mulling buying a powerline adapter, when I read this, from Which magazine.
There's one major caveat, however – powerline adapters won't work if your home electrical circuit is split over more than one ring. If your upstairs wiring is on a different electrical ring to your downstairs wiring, where your router lives, then you won't be able to extend the wi-fi upstairs using powerline adapters.
I'm not sure what this means, but I have a vague idea. The gateway is downstairs, the router I want to connect to is upstairs. They're on separate RCDs, which I assume means that they're on different rings… or does it?
I live in the UK.
Best Answer
Rings
Your quotation has a UK source. In the UK a "ring" refers to a ring-main also known as a ring-final circuit. This is the typical way UK houses have provided power to wall-sockets (outlets) since the 1950's.
They are called rings because they are connected in the topological equivalent of a large circle. There are two routes back to the consumer unit (main electrical distribution panel) from each socket.
Source: Wikimedia. CCASA 2.5 Ali@gwc.org.uk. This example ring has two spurs.
Usually the ground floor has one ring-main and the upstairs has a separate ring-main. Anything larger than the average 4-bed detached might have more ring-mains.
Note that UK lighting circuits are separate and are not ring-mains, they are radial circuits. There will also be separate dedicated radial circuits for ovens/cookers, boilers and electric-showers.
Newer UK consumer units (main panels) have effectively a split power bus with an RCD for each half. So it is likely that there are RCDs between your downstairs gateway and your upstairs router.
Source: Chase Electrical. Headings above MCBs are: (downstairs) lights, sockets, cooker ... (upstairs) lights, sockets, shower. This example has a separate RCBO (combined RCD and MCB) for smoke alarms?
Powerline
Across Different Rings
In my house I have an older arrangement that lacks RCDs in the consumer-unit. I use powerline networking between my upstairs router and my downstairs TV (it provides much better throughput and greater reliability than using WiFi in my specific circumstances) - So powerline networking can span rings.
Across RCDs
I don't know how much trouble (if any) your RCDs will cause. Anecdotal evidence suggests you might experience any of
What to do
I would go to a shop, clearly explain that I want to use the powerline units on separate rings each on a separate RCD. If they sell me some units for that scenario and they don't work, I would promptly return them as not "fit for purpose" under UK law (consumer rights act 2015).
...
Footnotes
(for Harper)
Ring final circuit test