Garage electrics

[Piglet333]

I want to put electrics in my garage to run a single socket and a strip light. I have a blanking plate in my down stairs utility room that has a wire in it, I have worked out it goes to my CU on a 32A RCD.

I was going to use this by running 1.5mm in heavy gauge conduit to my garage, then using a junction box split it, with one going to a 13amp socket and the other going to a fused 3amp spur for lighting (using 1mm). Is this ok?

and should I put a fused spur in the downstairs utility room and if so what fuse should I use?

(All cable in garage will be in conduit and socket/switch IP55)

tks

 

[mikeyd]

It will not be a 32A RCD. Is it an RCBO or an MCB? If it is an MCB is there also a seperate RCD in the consumer unit?

Either way you can't put a 1.5mm cable on that circuit. It would be need to be at least 4mm. Is the garage detached and if so how far away? Also if it is detached then SWA would be the usual cable rather than anything in a conduit.

EDIT: Did you add the line about the fused switch after I started typing the above? In an ideal world 1.5mm can carry just over 13A so you could fuse it down to 13A in the utility room but I'd expect after taking into account installation method and voltage drop (cable length) you wouldn't be able to do it.

 

[Piglet333]

Mike tanks for your quick reply.

You are correct that there is and RCD and a MCB, which is feeding some other plugs so I presummed that the cable would be 1.5mm, so I am a bit confused that you said I should use 4mm.

 

[Piglet333]

Garage is only 6 metres away forgot to say

 

[mikeyd]

Only one wire behind the blanking plate?

If other sockets are also on that circuit then I would have thought the cable would be 2.5mm (why do you assume 1.5mm?) Are there 2 cables wired in to the 32A MCB in the consumer unit? If so it's probably a standard ring final circuit.

If so and you only have one cable in the utility room then it's a spur off the ring. You could in theory extend it to your garage (Using suitable cable) and then in the garage fit a 13A fused switch and after that feed your 3A fused lighting circuit and a socket. Still depends on a few things though.

 

[EFLImpudence]

You are correct that there is and RCD and a MCB, which is feeding some other plugs so I presummed that the cable would be 1.5mm, so I am a bit confused that you said I should use 4mm.

http://www.csecables.com/nexans/current-carrying.asp

 

[Piglet333]

Yes there is only one cable in behind the blanking plate. There are two cables in the CU MCB and lookiing at it. So if I am correct I would put a 13amp fused spur here to the garage then what size cable to you suggest I use for the link to the garage socket and lighting?

tks

 

[ban-all-sheds]

Piglet - all your questions will be answered here:

• 
  
  
  
• //www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm (all subsections)
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• //www.diynot.com/wiki/electrics:mcb2
  
  
• http://www.tlc-direct.co.uk/Book/7.13.3.htm
  
  
• http://www.tlc-direct.co.uk/Book/8.1.1.htm
  
  
• //www.diynot.com/wiki/electrics:swa-gland
  
  
• //www.diynot.com/wiki/electrics:part-p
  
  
  Please get reading.