# RCBO vs RCCB



## J F Go (Mar 1, 2014)

You could probably get your answer a little quicker if you went to www.electrician forums.co.uk.,that's where those guys are.


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## Nuzzie (Jan 11, 2012)

Not sure how your board is wired but an RCCB should feed an MCB. An RCBO can be a direct replacement of an MCB though. If this isn't the case then no, your cable isn't protected.


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## Paulusgnome (Mar 28, 2009)

The use of RCCBs is prompted by either cost or space issues, although these days it is mostly about cost minimisation.
The RCCB allows several branch circuits to be RCD-protected by one single device, with the overcurrent/short circuit protection being provided by individual MCBs, one per circuit wired downstream of the RCCB. This usually works out to be the least expensive arrangement. 
If your RCBOs and RCCBs are all 18mm-wide (ie 2x MCB width) then this arrangement usually works out to take the least switchboard space.
Here in NZ, it was common to see whole houses wired with 2 or sometimes even just 1 RCCB to RCD-protect the whole installation until the rules were amended to restrict the number of branch curcuits to 3 per RCCB.
If cost is no problem, the best solution now is to use the new 9mm-wide RCBOs, one per branch circuit for all that need it, in place of MCBs.


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