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Thickness of underground cable

Discussion in 'Electrics UK' started by plcanonica, 7 Jul 2017.

  1. plcanonica

    plcanonica

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    Hi, I am building a summerhouse and want to lay an underground cable to the main house for electrics (it's only about 10m away). I will get an electrician to link it up to the house's electrics, but was wondering what sort of cable I will need. It will need to power a maximum of 3KW of appliances/lights at any one time.
    What type of cable should I buy?
    How deep should I lay it? (I'd prefer to dig less as I'll be doing it by hand and the ground is hard this time of year!).
    Any help gratefully appreciated.
     
  2. ban-all-sheds

    ban-all-sheds

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    You need to get the electrician on board now, as it will be his signature on the installation certificate, so it really ought to be him to make all the decisions, and be responsible for everything.

    Depending on how the supply is arranged, the work might be notifiable for Building Control. IMO the best way to supply an outbuilding would make it so, so another reason for an electrician to be in charge.

    That's not to say that you cannot do some of the work to keep the cost down. Digging the trench, for example - I'm sure he'd be delighted not to be shifting a ton or so of London clay. But once you have got an electrician, you and he can discuss how much of the work he is OK with you doing, and under what degree of direction/supervision.


    SWA, which will need to be properly glanded.


    I would caution against installing a cable sized for that load - if ever you find you need more (e.g. a hot tub in the future), you'd have to dig it up and start again. Overall the difference in cost between a small cable, and, say 10mm², won't be significant.


    The one your electrician specifies.


    There is no defined depth. Generally, in gardens, 450mm is regarded as OK, but when your electrician is there he can look at the route and tell you what depth it should be
     
  3. bernardgreen

    bernardgreen

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    Install a duct and then you can pull in whatever size cable the electrician specifies. Also consider a second duct for ELV cables such as telephone, alarms, data etc etc,
     
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  4. ban-all-sheds

    ban-all-sheds

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  5. motorbiking

    motorbiking

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    2.5mm SWA then it can be on a 16a. mcb radial or a 13a fused spur. I doubt many sparks would have a problem approving that. you can always disconnect it if you sell up

    don't forget warning tape above the cable.
     
  6. ban-all-sheds

    ban-all-sheds

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    An AAF way of doing circuit design.


    Doesn't matter. It is discourteous at least, and risky, to assume that an electrician will tell Building Control that he did the work, if notification is needed.

    What does anybody have to lose by making arrangements with an electrician up front, rather than at the end?


    Why on earth would that be necessary, or even desirable?
     
  7. seasickstevie

    seasickstevie

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    Weird !
     
  8. John D v2.0

    John D v2.0

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    the thread is ancient, bumping it for that?
     
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