Ring & Radial circuit regs

[RMR]

Hello there everyone,
I'm new to the site and have learned a lot in a short space of time, I must say this is an exellent site!

I have used the search but cant seem to find an exact answer to my quandary, so...

I was wondering what the regs are on radial and ring circuits.

I know ring circuits are fine with 2.5mm cable.
but are radial circuits legal as 4.0mm is no longer used ?
is a 2.5mm radial circuit legal ?

any advice much appreciated, ta!

 

[plugwash]

I know ring circuits are fine with 2.5mm cable.

indeed

but are radial circuits legal

yes

as 4.0mm is no longer used ?

you can still get 4mm the trouble is its only usable for a 32A radial if there are basically no derating factors involved.

is a 2.5mm radial circuit legal ?

yes provided a 20A breaker is used.

 

[viewer]

6mm cable is not much more expensive. You need the right depth backing boxes and good sockets. I have used Crabtree and found no problem with them when using 6mm.

 

[plugwash]

yeah wouldn't like to branch a 6mm radial though at least not at a normal socket. So such a circuit would be a PITA to expand.

 

[RMR]

thanks for your help Plugwash & Viewer, ta!

 

[jujubean]

thanks for your help Plugwash & Viewer, ta!

Gotta be carefull with 4mm on a 32 amp breaker. I think off the top of my head 4mm is rated at 32 amps clipped direct and 30 amps run in trunking....Dont quote me as I aint got a regs book handy
I for one will now run 2.5 cable radials in ground and first floor circuits off 20 amp breakers...when you work out the loading for average houses there is usually very little except of course in the kitchen where a ring is inevitable really..sometimes 2
Radials are much quicker to test, especially the r1 and r2's
Cheers

 

[Spark123]

The OP is over 2 years old!
4mm 2+e is rated 37A clipped direct without derating.