What’s a three-phase electricity supply and why do some properties have them?

Most houses only have a single-phase electricity supply which is more than enough for the power they need. But larger flats or commercial buildings need more electricity, so they’ll have a three-phase supply.

How to tell which supply you have

Check the service head/cut out (attached to your meter). There will be three fuses for a three-phase supply, and one for a one-phase supply.

An example of a three-phase supply