Powerline as a compromise

Powerline adapters promise to turn the house you already pay for into a backbone. The promise is not a lie so much as a laboratory. In a small flat on a quiet circuit they can be quietly excellent. In a Victorian conversion with two consumer units, a fish-tank pump and a charger on every strip, they are a mood. The only adult way to buy them is as a tested compromise with a returns window.

What they are

A pair of plugs that try to send ethernet as a signal on the mains. They need to be on the same electrical world. A studio is one world. A house with a garage board may be two.

The megabit number on the retail box is not a throughput warranty. Treat it as a model name.

What kills them

Surge-protected strips, cheap USB chargers, fridge motors, RCBOs that filter, and asking the signal to cross between boards. Also: pairing them, then moving one to a socket you never tested.

If the house already has noisy electrics, a more expensive pair will buy you a nicer plastic failure.

How to decide to keep them

A week of tests at 8am and 8pm, on the final sockets, with the noisy appliances on. If the worse hour is still above what the room needs, keep them. If it flutters, return them.

A good use: backhaul from a cupboard hub to a living-room access point. A bad use: pretending four powerline hops are a structured-cabling company.

The mains is a power product. Any data you get from it is a bonus you should measure.

Powerline is allowed to be a bit ugly and a bit brilliant. It is not allowed to be a substitute for a measurement.