"ARWadsworth" wrote
| A history question. As I see far more 15 amp fuse wired radials than
| 20 amp radials, did something change in the regs years ago to alter
| the rating of radials from 15 to 20 amp?

It used to be one 15A socket per 15A radial circuit, ie no allowance for
diversity. Smaller appliances would have been on 5A plugs.

With the introduction of 13A plugs, meaning the same circuit is used for
large and small appliances, diversity comes into play, allowing more than
one socket per circuit. And 2.5mm cable is adequate for 20A in most
circumstances (the 20A radial standard circuit specifies a *minimum* of
2.5mm, as indeed does the standard 32A ring circuit).

One reason for the design of the 30A ring circuit was the idea that two
existing 15A radials could be used as the basis for a new ring circuit.

Owain