RCD FOR CONSUMER UNITS

[kevon]

I been living in my house for the past five years. i have two consurmer units, with non of then having a rcd. The one unit has the following ciruits
a shower
a lighting circult
a ring circult
They are all in my converted garage
Do i need a rcd for this unit. If so what value and how is it done

 

[ban-all-sheds]

The shower circuit and the sockets should be on an RCD, but the lights should not, as being plunged into darkness if the RCD trips is at best a nuisance, at worst dangerous. To achieve this you either need to replace the CU with a split-load one, or replace the MCBs (if you've got MCBs and not fuses) with RCBOs.

The rating of the RCD you need will depend on the loading of the whole CU, but it'll probably be 80A or 100A.

What's the other CU for?

BUT your questions make me think that you shouldn't be DIYing this - if you do install a separate RCD you need to connect it directly to the meter tails, and unless you have an isolation switch that means pulling the main service fuse out.

Also, your RCD requirements my be affected by the type of earthing your incoming supply has - do you know what yours is?

Are you aware of the new Building Regulations requirements vis-a-vis electrical work?

I think that calls to a few electricians might be in order...