Changing sockets on a radial setup

[johngc]

I would like to convert a couple of sockets from single to double (and one to two doubles from a single) but have just found that my wiring is a radial setup.

The cable comes from the fuse box and feeds 5 sockets at the moment (two doubles and three singles), over two rooms (living room and dining room approx 9m x 4m area together). The cable runs in a crawl space under the floor so I can see that it is thicker than normal but I am not sure (without getting under the floor) what size it is.

I am happy enough to make the changes but have not dealt with a radial setup before. Will I be ok just replacing the sockets with doubles (and in one case two doubles) or will this put too much load on the system? I have read about being able to have as many sockets as I want in an area less than 50m2.

I would like to add another socket as well in another part of the room but am I right in thinking that I need an electrician to do that?

 

[rebuke]

What size is the breaker on the circuit, as that will dictate what the cable size needs to be.

The floor area restriction is based on a ring circuit, and is a (safe) rule of thumb, as far as I know it's not applicable to radials in that way (i.e. you have to calculate the voltage drop at the end of the cable etc).

Adding new sockets not in a kitchen/bathroom/other special area is not notifiable under Part P of the building regs, so you can do it yourself, but you still have to comply with P1, i.e. work must be safe etc (normal method of demonstrating compliance with P1 is to follow BS7671 (the wiring regs)).