Sockets on a radial circuit

[pc1966]

The answer, I think, is more a practical one than theoretical - at some point you'll run out of allowable Zs!!

From the OSG 4mm on 32A B is limited to 43m on VD (really 86m if loads are evenly distributed, as they probably would be with multiple sockets over a couple of rooms) and potentially much less on Zs (if, like me, you really don't like the idea of depending on the RCD for disconnection). Then it has 28m on TN-S typical max Ze

For comparison a RFC with 2.5mm on 32A B is 106m / 96m

For the OP's original 2.5mm & 20A probably around 84m on VD (distributed load) and 60-70m or so on Zs?

 

[Rockingit]

The true answer is provided in the Design Guide....

 

[Stephen-d]

Thanks for the information and help, the sockets won't be heavily loaded and not all used at the same time but just to be safe I think i am going to go with the 4mm radial ?

 

[Dartlec]

If you DID put 500 sockets in, you'd save on cable length...but your wrist would ache from making all the terminations...
and it would be rather more costly

Just been doing a loft extension with a client who really likes sockets.... A child's fairly normal size bedroom with 12 sockets - I think he wanted them near the bed, but couldn't decide where the bed was going!

Also 4 round pin sockets on the light circuit in the master bedroom, while will probably never get used....

I did put in 2 x 20A radials for 4 upstairs bedrooms when I might well have only gone with one in a 'normal' installation.

 

[brianmoooore]

If I could go back 40 years to when I wired my own house, each kid's bedroom would have been a separate 2.5mm2 radial. individual control over each room from the CU.

 

[nicebutdim]

Other than slightly increased initial costs, I can see only benefits to running several circuits where tradition might dictate that one would suffice.

Less inconvenience in the event of a fault. Less time involved in fault finding, should future issues arise. Reduced likelihood of a broken neck when extension leads are used in place of diagnosis and repair...

 

[Dartlec]

Other than slightly increased initial costs, I can see only benefits to running several circuits where tradition might dictate that one would suffice.

Less inconvenience in the event of a fault. Less time involved in fault finding, should future issues arise. Reduced likelihood of a broken neck when extension leads are used in place of diagnosis and repair...

If AFDDs are required in AMD2 then I can see new builds going back to as few circuits as possible!

 

[nicebutdim]

If AFDDs are required in AMD2 then I can see new builds going back to as few circuits as possible!

This is true, although their cost is likely to fall quite rapidly in such an eventuality.

 

[mydigitalhome]

Another consideration should be what’s the expected earth leakage on that circuit.