With reference to 433.1.204 and cable as installed has min capacity of 20A if protected by a 30A or 32A. If the protective device is reduced to 20A how is the new minimum as installed capacity calculated or arrived at ? I've been looking in the Electrical Installation Design Guide, but the answer is avoiding my eyes.
I chose the 1m example as one that almost never occurs, unless there is a socket in the cupboard with the consumer unit.
Surely it must depend very much upon the architecture. If the CU is in a utility room, there is almost certain to be a socket close by; and if the plumbing is in a particular place, that is where the washing machine, etc. must go.
In most dwellings, a ring around the periphery of the rooms with sockets at fairly regular intervals will do; but if it is along a service corridor with a room (or rooms) at the end, the situation is different.
I agree with ebee - not much point in making a radial to the far point with an empty leg on the way back. Better to wire it as a (4 mm²) radial in the first place. Saves a little copper too!
I suggest that any half-way competent electrician should be able to install (and I&T) both types of circuit and make a reasonable choice as to which suits best.
I chose the 1m example as one that almost never occurs, unless there is a socket in the cupboard with the consumer unit.
Surely it must depend very much upon the architecture. If the CU is in a utility room, there is almost certain to be a socket close by; and if the plumbing is in a particular place, that is where the washing machine, etc. must go.
In most dwellings, a ring around the periphery of the rooms with sockets at fairly regular intervals will do; but if it is along a service corridor with a room (or rooms) at the end, the situation is different.
I agree with ebee - not much point in making a radial to the far point with an empty leg on the way back. Better to wire it as a (4 mm²) radial in the first place. Saves a little copper too!
I suggest that any half-way competent electrician should be able to install (and I&T) both types of circuit and make a reasonable choice as to which suits best.
