Breaking into a ringmain.

[KNIPEX]

I am going to be breaking into a ringmain circuit to install a fused spur, which will all be surface mounted in trunking.

my question is will i need to change the mcb to rcbo as im changing the circuit slightly even though im NOT adding any sockets just a fuse spur, or will i get away with leaving it on an MCB

thanks in advance

 

[bugsy]

Assuming the MCB/RCBO is rated at 32a no OCPD changes required

 

[Jimmy Boy]

what's the FCU supplied circuit going to be used as a point of use ?

 

[Smugley]

There is no regulation limiting the number of sockets or fcus on a ring. It is up to the installer to decide whether the expected load is suitable for the circuit and ocpd.

 

[KNIPEX]

its more to do with the 17th edtion regs, if i was adding a socket to the circuit then i would have to change the mcb to rcbo to comply.

but as im only adding a fused spur which will control door access system, just wanted to know if i would need an rcbo on the ring final circuit.

 

[sjm]

If wiring is not concealed in a wall and you are not adding sockets then there is no requirement to change mcb to rcbo.

 

[Jimmy Boy]

There's no requirement to retrospectively update part of an old installation to 17th Edition. Read 411.3.3 brb

 

[KNIPEX]

ok thanks for the advice, however if i was adding a socket to an existing ring i would then have to install an rcbo as these could be used by anyone, even thought the existing ring wasnt covered before.

 

[telectrix]

that's my way of thinking as well. add socket = add RCD/RCBO, or. i suppose you could add an RCDsocket?

 

[jaresquire]

Reading the part of the brb quoted above, I would say the fcu is for a particular piece of equipment and so doesn't of its self need rcd protection even under 17th edition?
-Unless of course the cable to it warrants an rcd.