Your computer requires power to run. All personal computers run off the mains electricity supply (in the UK, this is 230V AC), so you need to plug in to that.

The UK plugs have three pins and are very stable (they don’t wobble out).

If nothing happens when you switch your machine on:

  • Check that both ends of the power cable are plugged in!
  • If the socket has its own switch, make sure it’s on.

UK plugs contain a fuse, so it’s possible (although rare) for the fuse to have blown in order to protect the circuit. If this is the case, investigate the cause of that problem before replacing the fuse.

On most computers today, you need at least two power cables: one for the computer, and one for each monitor.

Smaller devices might get power from other cables: USB and lightning connectors can both supply power (there will be a transformer on that cable too, if it’s plugged directly into the mains power).


Laptops, tablets, and phones all contain batteries that are charged by being connected to the mains supply (either via a transformer, or via another device such as a USB connection from another powered device).

The charging profile of different types of batteries can affect the optimal pattern to use when recharging them. For example, avoid exposing Lithium ion batteries to high temperatures (this can permanently reduce their ability to retain charge). If you want to maximise the lifetime of the battery in your laptop computer, check the recommendations from that particular manufacturer and model.