Garage Wiring Questions

Redisle

Hi Lads, few questions regarding wiring for a new garage extension. I have a good idea of what Im doing just need to confirm a few things.

Basically we have put a steel shed on to the back of an existing garage. Diagram below:

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0 is the existing garage and 1-3 are new. Simple timber framed sheds with insulated steel panels.

The existing garage is wired as follows:
House CU: Main Switch/63A Fuse --> 32A MCB --> Garage.

I believe the garage supply wire is 6 square. Measuring it with a callipers each conductor (measured from outside insulation) is about 5mm. Stranded wire. Or perhaps 4 square?

Garage CU: House feed --> 40A 30mA RCD
--> 25A MCB for Welding socket
--> 10A MCB for Lighting
--> 20A MCB for Sockets

The existing garage CU is the little red box in building 0 above.

Now as the existing garage CU is only 4 port I think I will replace it with a larger CU and run everything from that.

While keeping the existing setup for the original garage Im thinking:

2 10A MCB's for lighting (One for building 1 and 3, and one for 2). Will be mainly fluoroescent tube lighting.
2 20A Socket MCB's (Again one for 1 and 3 and one for 2) -- Radial circuits, maybe 3 or 4 double sockets in each building.
1 20A MCB for garage doors (2 electric roller doors).

Now for a few questions:

The existing garage CU dosen't have a main fuse/switch, only an RCD. Should I fit say a 30A main fuse/switch to the new board and run the lighting directly from that rather than through the RCD?

Regarding Wiring, any wiring I have done in the past in the house was done using the wire below, Flat grey wire, 2.5 for sockets and 1.5 for lights.



Im guessing this is the standard type of wire used in most installations? Im just wondering if I can use white PVC type wire instead for all the new runs? Think it looks better than the grey stuff and is easier to work with.

Also open to advice on conduits etc, I think I can get conduits that attach to surfaces and contain a few wire runs? For sockets I will probably go with Metal wall mount backing boxes and possibly sockets too.

Also, regarding the roller doors: The control boxes came fitted with a short cable run going to a 13 amp plug. Would it be neccessary to put some kind of fuse between the MCB and the doors or can I run them straight to the MCB?

Thanks for any advice.

maxfresh

Regarding the cable if its going to be seen eg. clipped to the wall you could use nymj cable instead of the grey twin and earth and if your running steel conduit which would look like a proper job the cables in the pipe will be single pvc eg. 2.5 brown ,blue and earth.

For the roller shutter supply you could connect it into a spur.

paddy147

maxfresh wrote: »

Regarding the cable if its going to be seen eg. clipped to the wall you could use nymj cable instead of the grey twin and earth and if your running steel conduit which would look like a proper job the cables in the pipe will be single pvc eg. 2.5 brown ,blue and earth.

For the roller shutter supply you could connect it into a spur.

Exactly what I had done with my garage and roller shutter door.

Steel conduit and nymj for lights and sockets.

Then fused spur for the leccy roller shutter door.:)

maxfresh

Would be a good idea to have a switch fuse in that sub main board ,derated to 40 amps.

Redisle

Thanks for the replies. What's the point in putting a 40A fuse in a main switch if it leads back to a 32A MCB in the house?

Regarding the rollers doors (there is two): Your saying it should be okay to take a fused spur off a socket radial for each door?

Would the NYMJ be much more expensive than the normal grey cable? I will be clipping it to walls, and up along roof joists etc so it sounds like the right job. Thanks.