Electric supply to the garage.

Discussion in 'Electricians' Talk' started by davehood, Apr 23, 2012.

  1. davehood

    davehood New Member

    Hi,
    I'm putting down a patio and I want to prepare to have an electricity supply put into the garage. Ideally I want the cabling to run under the patio. Obviously the wiring work is a job for an electrician, but I want to make life easier for him or her... Should I put in some sort of conduit or should I put down some armoured cable? The run from the consumer unit to the garage is approx 20 metres and some of the cable will need to be attached to the outside wall of the house. I also want it to be a ring circuit to enable me to use power tools inc a welder in the future.
    If I go for dropping armoured cabling in, would 16mm be up to the job? If I go the conduit route, what size would it need to be?   Thanks in anticipation, Dave.....
     
  2. J.P.

    J.P. New Member

    Armoured cable seems to be the cable of choice Dave and this is of course buried at the regulation depth which I think is 500mm but not sure - don't forget the hazard tape and stuff, and use the correct encapsulating mediums around the cable in the trench, and this includes the bed.

    I must say 16mm seems a tad ott, but of course if you let the forum know what sort of loadings are envisaged then the forum electricians will advise accordingly. What do you propose to do at DB1 (house)? For instance is there going to be a run of T + E from the DB to outside wall box which does not conform to the non use of an RCD/RCBO?

    Thus : -

    1 - Is it going to be run sub circuit style?

    2 - Is it going to be run sub main style?

    If you can get the SWA right up to switchfuse off Henley then nuisance trips and stuff is avoided at DB1 and it is then a sub main
     
  3. davehood

    davehood New Member

    Hi JP, I want the cicuit to be able to handle decent loads, such as power tools, a welder, compressor and a heater...... I suppose I'm just wanting to make life easier for the electrician who does the real work (and avoid the neccessity of digging up a new patio.) If I went for armoured cable I'm assuming that I would get enough for the entire run from the garage to the consumer unit, running some of it along the house wall. I thought 16mm would be needed due to the loads, the length of the run and the possible proximity of the cables as they went underground.....it might appear OTT but I thought I would err on the side of caution!   
     
  4. unphased

    unphased Screwfix Select

    Hi dave
    There are two options for preparing the future work in the garage. You can leave a 50mm duct in the ground with a draw wire (rope or similar) inside and accessible from both ends so that a cable an be pulled through later. Or you can install a steel wire armoured cable in the ground with sufficient length each end for the sparky to finish cleating it and running it to where it needs to go. A 16mm2 3-core will allow you maximum flexibilty as to the amount of power you need in the garage. Welders take a lot of juice. The SWA would be a sub-main from the house. Again, you can either utilise a spare way in the house fuseboard if available or you can split the tails and connect directly to a new fuseboard in the garage. Either option will do. Your spark will advise. Personally I would install the SWA as it will save a lot of time when you get the spark in to complete the job.

    Regards
     
  5. unphased

    unphased Screwfix Select

    Just some after thoughts. In the garage you would need a dedicated circuit for the welder, possibly a 32A circuit on a 6mm2 radial. A separate 32A ring circuit would serve the sockets and be sufficient to plug in a compressor and a heater (or you could adopt a 16A radial circuit for the heater). Lots of options. The usual 6A radial for lighting. I think a 16mm2 SWA wired off the tails in the house would be best.
     
  6. davehood

    davehood New Member

    Thanks for the prompt answers. I think I'll go for the armoured cable option, assuming that this is ok to run along the outside wall of the house to the consumer unit. Time to get the spade out! 
     
  7. J.P.

    J.P. New Member

    Hi Dave - 16mm it is m8 - upon reflection your cable choice is very sensible indeed, and my apologies for my use of the word ''ott''

    With Un's excellent advice it should be a nice install m8..:)
     
  8. unphased

    unphased Screwfix Select

    If you can, introduce the SWA at a shallow angle in to the ground in a straight line along the wall where it will be cleated. The SWA would be neat cleated at low level along the wall. Good luck. If you need any further help please post.

    :)
     
  9. Mr Bryan j Taylor

    Mr Bryan j Taylor New Member

    Hi I have just replaced the cable to my garage as it was old and unstable..
    I have volt tested it and it looks stable. Do I need an electrician to sign it off
     
  10. Mr Bryan j Taylor

    Mr Bryan j Taylor New Member

    Hi sorry if this is already posted but I replaced an old power cable from my house to my garage because it was very old and unstable(unsafe) I have volt tested and has a good stable current. I'm not burying it I will use trunking and put the cable inside to protect it.
    Do I need and electrician to test it??
     
  11. Coloumb

    Coloumb Screwfix Select

    As you have already done the work, if you want it tested, then a spark can only issue an EICR as opposed to a MWC. I am not sure if replacing an external entire sub-main counts as notifiable, I would think it would. So the issue will come up when you sell your house as you won't have a building control cert.

    Not sure what volt/current testing is but it doesn't sound like part of the testing requirements for 7671.

    It might have been better to start a new thread rather than bumping something from 2012. What would have been even better would have been to ask us about the work you have completed before starting it.
     
  12. Tony Goddard

    Tony Goddard Screwfix Select

    I would say, so long as you are not altering the circuit breaker at the CU or what it's feeding then its a like for like replacement of an existing cable / repair to existing circuit, so not notifiable (in England).

    You need to test the insulation of the cable, the earth loop impedance and the operation time of the RCD.
     

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