Garage Consumer Unit

[Festerfly]

situation is as follow:

My Mum has just had a new double garage built and the builders have asked me to do the wiring and such. They have already laid the SWA from the Garage to the house and are using an MK Sentry 4 way garage consumer unit. Just running 6 tubelights, and 3 or 4 double sockets.

Obviously i am connecting this smaller CU to the main house CU and was looking for some confirmation on what size MCB/RCBO to use? i was thinking that i would go with a RCBO and was trying to work out whether a 32A or a 40A would be better? The Main switch on the Sentry is a 40A.

Im leaning towards the 32A but am concerned that the House CU RCBO would be rated lower then the garage so if something tripped the circuit then the house one would go first so should i aim for higher and go with the 40A?

Cheers

Lee

p.s. im connecting it up on Sunday!

 

[saveloy]

Sorry but you need to post more details of the installation.

Design current, csa of the SWA, length of run, and installation method should all be assesed to determine the overall current carrying capacity of the SWA, which in turn will determine the appropriate rating of the protective device.

Hope this helps.

 

[The Truth]

32 amps is fine for the garage. In reallity the 'real' load will be very small if anything. best solution is 32amp or 40amp MCB at the supply end ( assuming you have the correct size cable i.e 6mm or 10mm2 swa ) and at the garage end swap the main switch in the consumer unit for a 30mA RCD. job done