Distribution boards (otherwise known as fuseboards) come in various shapes and sizes but you can expect them to look something like the picture above.
Distribution boards are made up of breaker switches (MCBs). Counting these will tell you the number of circuits present at your home or business. They may be all in a single board or a number of boards in different locations.
NB: You do not need to count the separate RCD switches or the red double-width main switches in this.
On some boards, there will be triple-width breakers known as 3-phase breakers.These also need to be included in your count, as 3-phase circuits.