Before my post yesterday about ring or radial for garage sockets I
assumed that I needed either a 2.5mmsq ring circuit or a 6mmsq radial
circuit. But one answer I received suggested that a 2.5mmsq radial would
suffice.

Wanting to understand this better I have spent quite some time this
morning looking on the Internet. My new understanding is:

Ring Circuit, 2.5mmsq, 32amp MCB, maximum floor area of 100sq m

Radial Circuit, 2.5mmsq, 20amp MCB, maximum floor area of 20sq m

Radial Circuit, 4mmsq, 32amp MCB, maximum floor area of 60sq m


Can someone give a concise description of why this is so? How is this
calculated? I would love to understand this fully.


Thanks,

Steve