MCB & RCD

[Kurt]

Sorry if this topic has been done to death already, I did a search on the forum but could not find what I wanted.

I need to install a power outlet in the garden and have been advised to use a 32 A circuit - comprising of 6mm armoured cable a 30ma RCD and a 30A MCB.

My question is in fitting the MCB/RCD to the consumer unit, do these two devices come as one unit, or do I have to fit one, then chain the power into the other. I have looked at many wholesale catalogues and I have never seen them mentioned together.

Thanks in advance.

 

[breezer]

its called an rcbo, try a search for power to garage, power to outbuilding, power to shed, lots of relly usefull info

 

[Kurt]

in part-reply to my own post, I notice that my consumer unit (new build property) already has a 30ma RCD fitted. Can I assume that this protects all circuits fed off the consumer unit?

If so, all I need is an MCB. Assuming I need to be able to deal with a 32A load, could I get away with a 30A MCB. A 40 A one sounds a bit excessive and possibly dangerous.

Thoughts please, and thanks.

 

[breezer]

so long as you have a spare way on the rcd side then yes

 

[Kurt]

thanks for your reply.

Is there a limit to the number of MCBs an RCD may feed? Is this a physical constraint of the consumer unit, or is there an imposed power limit.

I have four or five MCBs which appear to be associated with the RCD. There are spare slots in the consumer unit - is it normally straight forward to add another MCB to use the existing RCD?

thanks.

 

[breezer]

so long as it is same brand and on rcd side then yes, but i still suggest you look where i previously mentioned

 

[Lectrician]

And a 40A MCB will cost EXACTLY the same as a 32A BUT, cables size would dictate if you could use 40amp on your cable.

Let us know the length of run, what power you want (you say 32amp, but what actuall type of kit will be powered?). We can then calculate the correct size cable and MCB.

 

[dingbat]

Also, you don't want faults in the garden tripping out all your sockets in the house. I'd always opt for putting your outside circuit on the NON-RCD side of the CU, then protecting it with its own RCD.