Outside Cable through conduit

[pjo123]

I'm in the process of building my workshop from scratch and am nearly finished.

I intend running a 6mm cable from the spare 32amp fuse ini my CU to a Garage CU in my workshop, then running a 2.5mm ring round the workshop connected to a 32amp fuse in the garage CU and lights connected to 6amp.

The workshop is very close to my rear wall (less than a meter), and the garden wall is over 6ft high. see Photo

[img=http://img254.imageshack.us/img254/521/dsc00412da0.th.jpg]

I intend to run the 6mm cable under the upstairs floorboards, out through the rear house wall, along the garden wall (near the top) then into my workshop.

I presume it should be in conduit (live near the sea if that makes any difference)? If so, I'm happy running 25mm conduit. The only bit that confuses me is where to start the conduit. Should the conduit go through the house wall cavities or can the cable go out through the house wall then go into the conduit?

Many thanks

Phil

 

[Lectrician]

Conduit through wall would be better - easy to do on the wooden side. If you have not got a 25mm (actually, more like a 26mm), you could just let the conduit sit into the wall by 10mm or so.

32amp in the main CU and a 32amp in the shed offers no descrimination. A 40amp MCB in the house would be better, and most likely a 10mm submain.

 

[pjo123]

Thanks.

The Garage CU is 63Amp with 30mA RCD.

Currently on my main CU I have a spare 32amp breaker which is currently on the RCD side of the main CU. Was going to utilize this by moving it to the non RCD side of the main CU. Was hoping that the Garage CU would do all the work so to speak.

I don't need all that much power, while I have a fair bit of kit, it will be rare to have more than one bit of kit on at the same time (wont be using bandsaw or grinder at same time as lathe etc). 2.5mm on a 20amp fuse will probably do me for 80% of the time, went for 6mm to give me a little extra (eg heater in the winter).

I

 

[Lectrician]

Two 32amps is not a good idea.

You could fit a 4way CU with RCD incommer, and fit a few 2.5mm/20amp radials.

 

[pjo123]

Ok thanks.

 

[Space cat]

I never put a cable through a cavity without some kind of conduit around it. That's because we've got polystyrene bead insulation and polystyrene eats into PVC. (Actually it's the other way round; the plasticizer in the PVC attacks the polystyrene then the resulting chemical mess attacks the PVC.)

I put a single entry box on the end of the conduit and fix it to the wall with screws and silicone. The box has an extra hole in the back lined up with the tube in the wall.

Hint 1: Give your through-wall tube a slight downward slope towards the outside.

Hint 2: When you plan your conduit run, ask yourself how you would replace the cable if you had to. It's not easy pulling 6 sq mm round corners.

 

[pjo123]

Many thanks, tips much appreciated.