Best way to feed Garage electrics?

[wacman]

Recently had a 17th ed split load CU fitted in house. Garage has its own circuit fed directly from a 20 amp MCB in the house CU, which is rcd protected.

I have a couple of questions:

1, From the 20A in the house to the garage Fuse box is fed via 4ft of 2.5mm Twin & earth...is this cable size acceptable? Garage will have 2 x 80 watt flourescent lamps, and 1 radial circuit with 3 socket outlets. main loads will be freezer, treadmill and occasional Tumble dryer.

2, As its an old style fuse box in the garage, I plan to get this replaced with a 2 way consumer unit, as the house already has an rcd, would it be a good idea that the garage CU didn't have an rcd? I'm thinking nuisance tripping.

 

[wacman]

good stuff...keep it coming. so no rcd or rcbo on freezer. Next question is the size of cable supplying the garage and size of mcb in house CU. Its about 4ft from house Cu to garage CU. cable goes straight through cavity then up garage wall in pvc trunking to CU. Currently its 2.5mm T & E. This ok?

 

[Adam W]

4mm radial for garage from 30 or 32A MCB using house rcd, or separate RCBO on unprotected side
Lighting on fused spur.

... Or would that be over-simplifying things?

 

[jeremy]

Why not chuck in some 6 or 10mm. Upgradeproof and cost difference shouldn't be much. Don't forget through wall protection!! If Through wall protection is conductive should it be earthed? ideas welcomed.

 

[sparkylad]

wacman. the garage is treated as part of the main property if it is as you say attached. Unless you want to make uneccesary work ,then there is no need to change the supply cable.
On the point of RCD protection
1. If you have cables buried in the plaster less than 50mm deep then you will probably need RCD
2. All 13A. sockets in a domestic property require 30-ma RCD [ unless installed and identified as being for the permanent use of a specific piece of equipment.