Extending a full CU.

[STI]

I would like to RCD protect an existing cooker socket circuit in the kitchen. There is no room in the existing CU to add the RCD. So can i set up an RCBO in a new box, right next to the existing one, run a suitably sized cable, not tails, from the existing MCB to the new RCBO in the new "extended CU" and then power to the cooker from there.

Thanks for your help

 

[bongos]

You wouldn't put an RCBO in an additional enclosure usually as you already have overcurrent protection in the form of the existing MCB. Is there no way this MCB can be replaced with an RCBO instead?

Alternatively an inline RCD in a proper enclosure.

This work is notifiable...

 

[STI]

Hi Bongos,

So it is acceptable to have the MCB on the supply side of the RCD, I had got it in my mind an RCD circuit had to be set up as RCD - MCB (s)- Circuit. Thats why i thought i would have to use the RCBO.

Or am i mis-understanding how an inline RCD is set up.

Sorry also to your question on will it not fit the answer is no unfortunately and thanks for the reminder on the notifiable bit, i know the kitchen is a special zone.

 

[kai]

Why can't you connect a new small 2way consumer unit, from the bottom output terminals of the main switch on the existing unit?
(Most modern consumer units have a pair of output terminals at the bottom of the mains switch.)

 

[sparkwright]

what about keeping the existing mcb and installing an rccb (NOT an rcbo) in a small enclosure adjacent the consumer unit. in other words

mcb - rccb enclosure - cooker switch - cooker

get one at minimum of 32 A, if the mcb is 32 A. a 40 A rccb is probably easier to obtain.

 

[Steve]

Hi Bongos,

So it is acceptable to have the MCB on the supply side of the RCD, I had got it in my mind an RCD circuit had to be set up as RCD - MCB (s)- Circuit. Thats why i thought i would have to use the RCBO.

Or am i mis-understanding how an inline RCD is set up..

An RCBO is an MCB and a RCD in one.

If you have an RCBO you dont need an MCB or an RCD for the associated circuit.

 

[flameport]

This is an example of an RCD and enclosure:

You fit this after the existing MCB.

What was the reasoning for adding the RCD anyway?

 

[STI]

Thanks everyone for the really helpfull replies. The pictures are great. The reason i am doing this is i need to move the position of my cooker. So at the moment i have a cooker switch above the kitchen surfaces connected to a cable outlet behind the cooker. The thoughts are rather than run a new cable from the CU to the new switch and outlet just run additional cable from the existing outlet , behind the kitchen units to a new outlet which is in the new position. As the extension wire will be clipped directly to the wall and not physicallyprotected other than by the sheath i thought the introduction of an RCD would be wise, plus i thought as this would be adding a new socket to comply with the regs i would now need to add the rcd.

One question what is a RCCB and how does it differ from an RCBO

 

[sparkwright]

Thanks everyone for the really helpfull replies. The pictures are great. The reason i am doing this is i need to move the position of my cooker. So at the moment i have a cooker switch above the kitchen surfaces connected to a cable outlet behind the cooker. The thoughts are rather than run a new cable from the CU to the new switch and outlet just run additional cable from the existing outlet , behind the kitchen units to a new outlet which is in the new position. As the extension wire will be clipped directly to the wall and not mechanicaly protected i thought the introduction of an RCD would be wise.

One question what is a RCCB and how does it differ from an RCBO

an rcbo is an mcb combined with rcd. a rccb is just rcd.

an rccb will have a maximum current rating that must not be exceeded, but it does not offer overcurrent protection like an mcb or rcbo would.

since you have an mcb already you only need rcd protection which would be an in-line rccb.

the alternative would be just to replace the mcb with an rcbo, but you may struggle to get one that would fit your cu.

flameport's picture is of an rccb.