Electric feed to the garden and shed

[wazzag]

Hi,

I would like to feed my garden shed from a consumer unit I have in a brick outhouse/utility room.
The route the cable will be taking is as follows:

- Small Consumer unit in brick building to the side of my house (empty slots are available in the unit for RCD/MCB/RCBOs)

- Along the roof of the brick building and down a wall to the garden (approx 5 meters in total)

- Buried in the garden all the way to the shed (approx 15 meters)

- In the shed I would like 3 or 4 twin sockets and some lighting. I'd like to power a fridge/freezer and some power tools from the sockets (nothing too large - we're not talking lathes/milling machines - more like hand held drills etc)

Questions:
1) What do I need in the consumer unit - an RCBO? What rating?
2) What cable type and rating do I need for the various parts of the route? (I assume I need SWA for the garden stretch but can I join that to standard cable using waterproof junction boxes etc)
3) In the shed can I wire the sockets (using a radial circuit) and the lights directly from the feed from the garden using junction boxes?

Thanks,
Warren

 

[ban-all-sheds]

• You need to read these:
  
  
  
• http://www.tlc-direct.co.uk/Book/6.1.1.htm
  
  
• //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
  

 

[wazzag]

Thanks, i'll get reading.

In the meantime can anyone give me some rough answers please?

 

[ban-all-sheds]

If you want to do this, you have to do it, and assume total responsibility for every aspect of design, installation and testing.

Re 1) - You need to decide where you would want to go if an RCD trips, whether you should have a fridge/freezer on an RCD, and what load you want to design for.

Re 2) - Why not use SWA for the whole route? The size of cable will be determined by your calculations for voltage drop, current carrying capacity and fault loop resistance.

Re 3) - It's unlikely that your lights and switches will be rated highly enough to be on the socket circuit, and you need to think about whether you would be happy for the lights to go out if the circuit tripped while you were holding a power tool.

FWIW, my preferred approach to supplying an outbuilding is a local CU supplied by SWA running from a switchfuse in the house which is supplied directly by the meter tails.